Fruit & Vegetable Gardening; The Definitive Guide to Successful Growing - Dk Publishing

PLANT PROBLEMS 249 COMMON FRUIT PROBLEMS Crop Symptoms Crop Symptoms Roots Leaves Fruits Roots Leaves Fruits and stems and flowers and stems and flowers Cherry, sweet Pear & cherry Fruit fly Pineapple Phytophthora Mealybugs — and sour (cont.) slugworm Plum Root knot Scale insect Scorch Fruit fly nematode Red spider mite Birds Citrus fruit Crown rot Silver leaf Viruses Thrips Brown rot Winter moth Honey fungus Frost damage Birds Phytophthora Birds Plum fruit moth Mealybugs Canker (bacterial) Cranberry Honey fungus Red spider mite Birds Prickly pear — Caterpillars — Fig Scale insect Frost damage Quince Honey fungus Plum leaf-curling, Blossom wilt Honey fungus Thrips mealy plum aphid Brown rot Gooseberry Phytophthora Whitefly American goose- Red spider mite Frost damage berry mildew Silver leaf Monilinia blight Chlorosis Birds Raspberry Honey fungus Winter moth Quince leaf Rusts Squirrels Phytophthora blight Mealybugs Grape vine Honey fungus Brown scale Birds Birds Phytophthora Coral spot Botrytis Fireblight Botrytis Vine weevil Frost damage Shanking of Frost damage Raspberry beetle Red spider mite grapes Monilinia blight Wasps Red and Honey fungus Powdery mildew Birds American goose- white currant Phytophthora Quince leaf Botrytis berry mildew Nut weevil blight Hazelnut Honey fungus Aphids Squirrels Strawberry Honey fungus Verticillium wilt Birds Phytophthora Birds Red core Botrytis Hybrid berries Botrytis Monilinia blight Verticillium wilt Aphids Powdery mildew Honey fungus Capsid bug Vine weevil Cane spot Slugs & Snails Kiwi fruit Caterpillars Birds Chlorosis Strawberry seed Medlar Honey fungus Gooseberry Fruit fly Walnut Honey fungus Leaf spot (fungal) beetle Honey fungus dieback Phytophthora Raspberry cane blight Birds Mulberry Phytophthora Gooseberry sawfly Cucumber mosaic Raspberry leaf Squirrels Olive Root knot Leaf spot (fungal) virus and bud mite nematode Fruit fly Raspberry spur Brown scale blight Downy mildew Brown rot Raspberry viruses Magnesium Frost damage Rusts deficiency Split stone Mealybugs Squirrels Aphids Oedema Coral spot Powdery mildew Birds Leaf spot (fungal) Red spider mite Blossom wilt Capsid bug Scorching Boron deficiency Gooseberry sawfly Vine weevil Brown rot Rusts Codling moth Aphids Fireblight Aphids Powdery mildew Frost damage Powdery mildew Pear midge Red spider mite As for Pear rust Strawberry Blackberry Pear scab viruses No major problems Walnut blotch Walnut leaf blight Leaf spot Passion fruit Honey fungus Monilinia blight Blackfly on artichoke Peach and Honey fungus Mulberry canker There are some nectarine Phytophthora pests and diseases Olive scab that can afflict Pear Honey fungus Red spider mite virtually any crop Phytophthora Scale insect in the garden, such Thrips as these blackfly, Verticillium wilt in addition to other Whitefly types of aphid, slug and snail, Aphids honey fungus, and Mealybug damping off. Such Red spider mite problems are listed Scale insect in the charts above only if they are a Aphids particular nuisance. Brown scale Canker (bacterial) Peach leaf curl Red spider mite Silver leaf Aphids Pear scab Birds Canker (fungal) Caterpillars Fireblight Pear leaf blister mite Pear & cherry slugworm Pear rust Replant disease Winter moth

250 MOST COMMON PROBLEMS Most common problems Use this index to locate details of the most common problems. Aleyrodes proletella p.264 Botrytis cinerea p.252 Brachycaudus helichrysi p.259 Bremia lactucae p.255 Byturus tomentosus p.260 Cabbage worm/whitefly Botrytis damage Plum leaf-curling Downy mildew Raspberry beetle aphid damage on lettuce damage on fruits Cydia nigricana p.258 Cydia pomonella p.254 Milax species p.262 Nematus ribesii p.256 Otiorhynchus sulcatus p.263 Codling moth Keeled slug Gooseberry sawfly damage on apple damage on potato Pea moth caterpillar larvae Vine weevil larvae Phyllotreta species p.255 Phytophthora infestans p.260 Plasmodiophora p.254 Podosphaera leucotricha p.251 Psila rosae p.253 brassicae Flea beetle Clubroot Apple powdery Carrot fly damage damage on baby turnip Potato blight on tomato mildew Puccinia allii p.257 Sclerotinia sclerotiorum p.262 Sclerotium cepivorum p.258 Streptomyces scabies p.260 Taphrina deformans p.258 Leek rust Sclerotinia on lettuce Onion white rot Potato common scab Peach leaf curl Tetranychus urticae p.261 Venturia inaequalis p.251 p.254 p.252 p.257 Red spider mite Apple scab Cucumber mosaic Magnesium damage on cucumber leaf virus on zucchini Bitter pit on apple deficiency on tomato

A–Z OF PLANT PROBLEMS 251 A–Z OF PLANT PROBLEMS American gooseberry cyhalothrin, or thiacloprid can be used ■ Causes The fungus Venturia inaequalis ■ Cause Adults and larvae of the leaf mildew on vegetables and fruits listed in pesticide on apples and pears, Venturia pirina on beetle Crioceris asparagi. Adults are manufacturers’ instructions. Details of pears, and Spilocaea oleagina on olives. 1⁄4–3⁄8in (6–8mm) long, black with a ■ Crops affected Black currant and control on specific plants are listed in The fungi overwinter on young stems red thorax, and with six yellow gooseber r y. individual entries. and fallen leaves. Scabs are most blotches on the wing cases. In late ■ Symptoms Powdery, gray-white See also Black bean aphid, Lettuce root prevalent in damp seasons and on trees spring, they emerge from the soil to fungal growth appears on upper leaf aphid, Mealy cabbage aphid, Pea aphid, with crowded branches. lay eggs on stems and leaves. The gray- surfaces, stems, and fruits. Young Plum leaf-curling aphid, Root aphid, ■ Control Gather up and destroy fallen black, hump-backed larvae, to 1⁄2in growth may become distorted and die Rosy apple aphid, Woolly aphid. leaves. Prune out cracked or scabby (1cm) long, have three pairs of legs. off. Mildew on the skin of fruits turns shoots to limit overwintering. Prune They appear in late spring or early fall; buff as it ages and can be scraped off. Apple canker: see Canker (fungal). regularly to ensure good air f low, there are two generations each year. Fruits are unsightly but edible, although Apple and pear canker: see Canker and to reduce conditions favorable to ■ Control Destroy overwintering they turn brown when cooked. (fungal). fungal growth. Seek cultivars showing beetles by burning old stems at the ■ Cause The fungus Podosphaera resistance, such as dessert apples end of the season. From late spring, mors-uvae, which is encouraged by Apple powdery mildew ‘Ashmead’s Kernel’, ‘Discovery’, ‘Sunset’, search for and destroy adults and larvae stagnant air around the branches and and ‘Laxton’s Fortune’, and culinary by hand. On larger plots, this is by excessive use of nitrogen fertilizers. ■ Crops affected Apple, and less apples ‘Edward VII’ and ‘Grenadier’. The impracticable, so spray with pyrethrum It overwinters on the branches and in seriously, pear, quince, and medlar. pears ‘Jargonelle’ and ‘Catillac’ similarly at dusk, so as not to harm day-f lying the buds. ■ Symptoms Leaves are covered in show resistance. Difencoconazole or bees and other beneficial insects. ■ Control Prune out affected branches as powdery white fungal growth (see myclobutanil may be used to control seen; prune to thin growth and improve p.250); young leaves may be badly these diseases. Bacterial canker: see Canker. air circulation. Use a general fertilizer infected from spores that overwintered rather than a high-nitrogen one. Grow from the previous year. They become Apple sucker Badger cultivars with some resistance, such as distorted, fail to develop fully, and die ‘Invicta’ or ‘Greenfinch’. Spray with a prematurely. Stems may show silvery ■ Crops affected Apple. ■ Crops affected Carrots, hazelnut, fungicide containing myclobutanil. white patches in winter. ■ Symptoms Pale green, f lattened raspberry, strawberry, and corn. ■ Cause The fungus Podosphaera insects, to 1⁄12in (2mm) long, infest ■ Symptoms Nuts and fruits are taken; Anthracnose leucotricha overwinters on apple buds f lower trusses in spring, turning the plants are often severely trampled by or on stems. Spread and development petals brown and killing the blossom these heavy, burly, and determined ■ Crops affected Various, especially is rapid in hot summers, especially if infestation is heavy. mammals. The long forepaws with French, dwarf, and runner bean, and when dews are heavy. Dry soils also ■ Cause Sap-sucking, aphidlike insects, prominent claws leave characteristic cucumber. encourage development. Psylla mali, hatch from overwintering prints and their droppings usually have ■ Symptoms Various fungi cause spots ■ Control Keep apples well watered and eggs as the tree comes into leaf. Damage a muddy consistency. There may also or patches of discoloration on leaves, well mulched to conserve water. Prune is caused by immature nymphs (described be evidence of digging, and coarse, stems, and on bean pods. Affected tissue out badly affected growth. Keep the above) at f lowering time. The adult, gray and white hairs remain on fences may die; in severe cases, the whole plant crowns of trees open to permit good air which looks like a winged aphid, is where they gain entry. dies back. On bean crops, longitudinal, circulation. Spray with a fungicide that present on the foliage after petal fall. ■ Cause Badgers, Meles meles, are sunken brown marks appear on stems. contains difenoconazole or myclobutanil. ■ Control Use a plant oil winter wash omnivores, but they, and especially Leaf veins may develop red coloration to control overwintering eggs. Spray their cubs, appear to prefer vegetable and leaves may brown and die off. Red- Apple sawfly nymphs with deltamethrin or pyrethrum food sources in late summer and fall. brown spots appear on pods, followed at the green bud stage, before f lowering. They are nocturnal and emerge at in wet weather by pink slimy growths. ■ Crops affected Apple. dusk, although the cubs will forage ■ Causes Colletotrichum species are ■ Symptoms Fruitlets fall off in early Artichoke bud rot in daylight if food is scarce in summer. the most common agents; the bean to midsummer and have maggot holes Badgers are usually a denizen of rural anthracnose fungus, Colletotrichum in the side. This exit hole is filled with ■ Crops affected Artichoke and habitats, but they are now increasingly lindemuthianum, is usually seed-borne. frass (excrement) produced by a cardoon artichoke. seen in suburban gardens. Spores are spread by rain or water caterpillar-like, brown-headed white ■ Symptoms The f lowerheads develop ■ Control Regularly maintained, stout splash from infected seedlings to larva. Mature fruits may be misshapen pale brown spots and later the entire fencing is the only option; they are nearby plants. and marked with a ribbon-like scar, head becomes shriveled and infected by great and persistent diggers. Badgers ■ Control Remove infected plants as usually from the bottom to the middle f luffy gray fungal growth. Sometimes, and their setts are protected in some soon as seen; do not save their seed. of the fruit. pinprick-sized, black fruiting bodies parts of North America. Use resistant cultivars of beans, such as ■ Cause The sawf ly, Hoplocampa (sclerotia) are seen on the fungal mass. ‘Aramis’ or ‘Rido Kenyan’. There are testudinea, lays its eggs in the fruitlets If infection is extensive, the whole crop Bean aphid: see Black bean aphid. currently no fungicides available to at f lowering time. After hatching, may be lost. Bean halo blight: see Halo blight. gardeners to control this disease. the larva tunnels into the fruit, first ■ Cause The gray mold fungus, Botrytis Bean root aphid: see Root aphid. beneath the skin, then to the core. cinerea. Spores are spread readily by water Bean rust: see Rusts. Aphids Badly damaged fruitlets fall, but if the splash and air currents, and they persist larva dies before it reaches the core, from year to year in the soil, or on plant Bean beetle ■ Crops affected Few plants are the fruit will mature (although it will debris, as sclerotia. unaffected by aphids; some are host- be scarred and misshapen). The larvae ■ Control Good cultural practice and ■ Crops affected Fava bean and pea. plant specific. leave the fruit to pupate in the soil. hygiene are the first lines of defense, ■ Symptoms Holes in dry bean and ■ Symptoms Affected plants show ■ Control Pick off and destroy damaged since control of such a widespread fungus pea seeds, which are the exit holes varying degrees of reduced growth fruitlets before the larvae can escape is difficult. Avoid damp or shaded sites. of adult beetles. In fresh beans, small, and leaf distortion. Upper leaf surfaces and pupate. If the crop has been Keep plants growing well and in good pale, circular patches on the seed coat are often sticky with the honeydew significantly affected in previous years, health by regular feeding and watering. indicate the presence of the beetle excreted by aphids and this often spray with deltamethrin within seven Remove any dying buds or f lowerheads grub within. becomes infested by black sooty mold. days of petal fall. promptly as soon as seen; the fungus will ■ Causes Several seed beetles affect The nymphs shed their whitish skins as rapidly invade dying or damaged tissues beans and peas. Bruchus rufimanus is they grow, which accumulate on leaves Apple, pear, and and will spread to previously unaffected usually the culprit in fava beans. It below those on which aphids are feeding. olive scabs ones. Cut back to clean, healthy stems. lays its eggs in the pods as the seeds Viruses are often spread from one plant Clear away all plant debris promptly. are forming. The grubs are usually to another on aphid mouthparts. ■ Crops affected Apple, pear, and olive. See also Botrytis. unnoticed in cooked beans, but they ■ Cause Sap-sucking insects, about ■ Symptoms Black or brown scabby develop during storage and emerge 1⁄12in (2mm) long, may be green, gray, areas on the surface of young fruits Asparagus beetle as adults the following year. pink, black, yellow, or brown, depending (see p.250). In severe cases, it may be ■ Control Check for exit holes before on species. widespread and cause misshapen, cracked ■ Crops affected Asparagus. sowing seeds and discard badly damaged ■ Control Organic treatments include fruits. Brown or olive-green spots appear ■ Symptoms Asparagus plants defoliated seeds. The grub eats only part of the pyrethrum, fatty acids, and plant oils. on the leaves, which may appear blistered. as beetle adults and larvae strip the cotyledons rather than the seed embryo, Control overwintering eggs in winter Early leaf fall can occur, reducing the outer bark and leaves from the stem. so the seed can still germinate. There is on deciduous fruit trees or bushes with crop the following year. Young shoots Damaged areas become yellow-brown no chemical control currently available a plant oil wash. Deltamethrin, lambda- are also attacked. and desiccated. for garden use.

252 A–Z OF PLANT PROBLEMS Bean fly only for a while; birds quickly get used leaf crumpling. There are three ■ Control Avoid growing early varieties to them, especially if they are hungry generations each summer; the first of susceptible vegetables, as these are ■ Crops affected French and runner and other food sources are scarce. symptoms appear with the f lowers more prone to bolting. Choose cultivars bean, cucurbits. Shooting pigeons is not an option in late spring. While the maggots that are listed as having bolt-resistance. ■ Symptoms Ragged leaves and in suburban and urban areas. pupate in the soil, several normal leaves damaged stems are seen on newly may appear before the next generation Boron deficiency germinated seedlings; sometimes, Bitter fruits becomes active. seedlings fail to emerge, having been ■ Control Choose resistant cultivars, ■ Crops affected Listed below. eaten below soil level. Provided that ■ Crops affected Cucumber and such as ‘Ben Connan’ or ‘Ben Sarek’. ■ Symptoms The symptoms vary with the growing point has not been gherkin. The first generation is potentially the the crop affected. destroyed, plants will survive, although ■ Symptoms Fruits have a bitter f lavor. most harmful, since it can limit normal ■ Beets: Rough, cankered patches on growth will be slow at first and ■ Causes Pollination of fruit-bearing, shoot extension. There are no chemical roots, often with secondary rotting at the sideshoots may develop. female f lowers by male f lowers, or an controls approved for garden use. heart, revealed as the development of ■ Cause The maggots of Delia platura. excess of nitrogen in the soil. brown rings in the inner root tissue and The adults look like house f lies. ■ Control Remove all male f lowers as Black currant gall mite: see Big bud mite. crown. Leaves are small and necrotic. ■ Control Slow-germinating seed is they appear (female f lowers have tiny, Black currant reversion: see Reversion ■ Cabbage: Distorted leaves and hollow most vulnerable, so avoid sowing when nascent fruit immediately behind the disease. areas in the stems. the soil is cold or wet. Instead, sow in f lower) or grow all-female cultivars. Blackfly: see Black bean aphid. ■ Carrot: Splitting of root, often pots or trays and set out after the first Use a balanced rather than a high- Black leg: see Potato black leg. exposing a grayish central core, and true leaves have unfolded. The adult nitrogen fertilizer. splitting of stems. Yellow and pink f ly is attracted to fresh organic matter, Blossom end rot discoloration of leaves. so apply manures in fall rather than Bitter pit ■ Cauliflower: Poor curd development spring. There are no approved ■ Crops affected Tomato and sweet and browning of curds. Roughening insecticides to control this pest. ■ Crops affected Apple. pepper. of main stems, leaf stalks, and midribs. ■ Symptoms Apple skins speckled with ■ Symptoms A sunken patch occurs at ■ Celery: Transverse cracks in the outer Bean weevil: see Pea and bean weevil. slightly sunken brown spots, usually the blossom end of developing fruits; the leaf stalk, followed by reddening of inner 1⁄16–1⁄8in (1–3mm) in diameter (see p.250). skin at the base becomes leathery, then tissues, sometimes with leaf distortion. Big bud mite The f lesh tastes slightly bitter. The turns brown or black. Not all fruits in a ■ Pear: Fruits are distorted, with hard marks sometimes develop while the truss will be affected, nor will all trusses brown f lecks in the f lesh. This may be ■ Crops affected Black currant. fruits are on the tree; more often, they on the same plant necessarily suffer. accompanied by slight shoot dieback. ■ Symptoms Winter buds are develop in storage. Large fruits and ■ Causes Calcium deficiency due ■ Radish: Dull, split skin with woody abnormally large and rounded and do those from heavy cropping trees are to dry conditions at the plant roots f lesh. not develop into leaves or stems. Each most susceptible. inhibiting its uptake. Lack of calcium ■ Rutabaga and turnip: “Brown heart,” bud contains hundreds of microscopic ■ Causes Calcium deficiency in the causes cells to collapse and discolor. A which is revealed when the roots are white mites. The buds become swollen fruits. Soil calcium levels may be very acidic growing medium increases cut across as gray or brown, discolored in winter, but desiccated big buds can adequate, but in dry weather the tree the problem. areas. These may appear in concentric be found at any time of year. Infestation cannot take up sufficient calcium—hence ■ Control Ensure an adequate and rings in the lower parts of the root. causes loss of vigor, but, more seriously, the greater susceptibility of large fruits regular water supply. If rot does develop, ■ Strawberry: General stunting. Small the mite can spread reversion disease and heavy-cropping trees. The condition remove affected fruits and improve leaves are puckered and yellowed at tips. (see p. 261). may also be caused by excessive levels of irrigation. Small-fruited cultivars and Berries are small and pale, typically ■ Cause A mite, Cecidophyopsis ribis. calcium and magnesium in the fruit. plants grown in open ground or large forming a “waist” close to the calyx. The mites breed in summer and fall and ■ Control Use a mulch to retain soil containers are less susceptible. Not a common aff liction. feed inside the buds during winter. At moisture and keep trees well watered. ■ Causes Boron deficiency often occurs bud burst in early spring, they move Avoid excessive use of high-nitrogen Blossom wilt on light soils because this element is on to infest previously healthy buds. fertilizers; use balanced fertilizers readily leached out by high rainfall; it ■ Control Removing big buds by instead. Spray developing fruits with ■ Crops affected Apple, apricot, cherry, also occurs if soil is limed excessively hand from lightly infested bushes in calcium nitrate solution between early plum, peach, and pear. or when soil is allowed to become winter, well before bud burst, provides summer and early fall. ‘Bramley’s ■ Symptoms Flower trusses wither very dry. a measure of control. Dig up and burn Seedling’, ‘Discovery’, and Crispin shortly after emergence. Dead trusses ■ Control For vegetable and strawberry badly affected plants after fruiting and (‘Mutsu’) fruits may be damaged by remain on the tree, forming a source crops, apply 1oz of borax per 175sq ft replace in fall. The cultivar ‘Ben Hope’ this treatment, so use it with care on of infection for leaves, which wilt, (35g per 20sq m) of ground before is resistant. Chemicals available to these cultivars. turn brown, and die, remaining on sowing or planting. Mix the borax with gardeners do not control the mites. the branch. Raised, buff-colored, fine horticultural sand to make even Black bean aphid pinprick-sized fungal pustules appear distribution easier. For pear crops, spray Birds on infected areas. Localized dieback at petal fall with 21⁄2oz borax in 5 gallons ■ Crops affected Beans, beets, cardoon, of stems may occur. (70g in 22 liters of water) together with ■ Crops affected Most soft and tree and artichoke. ■ Causes The fungus Monilinia laxa a wetting agent. Take care when fruits, onion sets, pea, bean, brassicas, ■ Symptoms Clusters of black insects, or, on apple crops, M. laxa f. laxa. It applying borax; it is easy to overdo it. spinaches, and corn. to 1⁄12in (2mm) long, congregate at stem may overwinter as cankers on affected ■ Symptoms Birds may eat f lower buds, tips and beneath leaves. Plants are stems, or as pustules on f lowers and Botrytis peck or eat whole fruits, strip leaves off weakened and bean pods fail to develop. foliage. Wind-borne spores spread brassicas and peas, eat pea and bean seeds ■ Cause A sap-feeding aphid, most rapidly in damp weather. ■ Crops affected Various. and lettuce seedlings, or pull up newly Aphis fabae. ■ Control Prune out infected f lower ■ Symptoms Fuzzy, gray, off-white, planted brassicas and onion sets. ■ Control Inspect plants regularly; if trusses before infection spreads to the or gray-brown fungal growth (see ■ Causes Bullfinches are the prime fava beans are almost full size, pinch leaves or into the spur. Difencoconazole p.250) on infected areas (hence the suspect if fruit tree f lower buds are eaten; out infested shoot tips and destroy them. is labeled to control blossom wilt on common name, gray mold). This the brown bud scales are discarded and The organic insecticides pyrethrum cherries, plums, gages, damsons, and ubiquitous, air-borne fungus lives on are easily visible in winter if snow or and fatty acids, are effective if used ornamental trees. dead or living plant material, and can frost are on the ground. Since they f lock before heavy infestations develop. Use attack most above-ground tissues. It and are voracious, damage can be severe. deltamethrin or lambda-cyhalothrin Blotchy ripening: see Tomato blotchy usually gains entry through wounds. The terminal buds are often left intact, on bean crops. ripening. and in spring, barren shoots with f lowers Fruits may be infected through open only at the tips confirm the culprits. Blackberry cane spot: see Cane spot. Bolting f lowers; the fungus remains dormant Blackbirds, starlings, and other birds until fruit ripens. Prior to development peck holes in fruits and eat whole small Black currant gall midge ■ Crops affected Various, including of the fungal fruiting stage, plant tissue fruits, such as raspberries. Blackbirds are brassicas, the onion family, and spinach. becomes discolored, often turning the main culprits in pulling up onion ■ Crops affected Black currant. ■ Symptoms Premature production brown and soft. Growth above the site sets, and pigeons will damage the foliage ■ Symptoms Leaves are crumpled and of f lowers and seeds, before full of infection may deteriorate, leaves may of brassicas and peas. fail to develop to their full size; they may development of the crop, or before yellow and wilt, and f lowers and fruit ■ Control Small trees and soft fruits can become desiccated and die. Shoot tips harvest is complete. may die. Infection of petals or fruit can be netted or grown in a fruit cage; on may also be killed, causing branching. ■ Causes Various factors. The most cause color changes without rotting; larger trees, protect best fruit trusses ■ Causes White maggots, up to common include exposure to low petals appear bleached or form pale with bags of muslin or old panty hose. 1⁄12in (2mm) long, feed on leaves at temperatures at a critical growth stage, brown spots (ghost spotting). The fungal For other crops, fine-gauge netting is the shoot tips. They are larvae of the often accompanying a cold, late onset resting bodies—small, black sclerotia— the only certain way of deterring birds. midge Dasineura tetensi, which produce of spring, and excessively dry soil resist a wide range of adverse conditions, Scarecrows, humming lines, glitter strips, chemicals that cause the characteristic conditions during early growth stages. staying dormant until conditions are and model cats or predator birds work suitable for their growth.

A–Z OF PLANT PROBLEMS 253 ■ Causes The fungus Botrytis cinerea; ■ Cause The maggots of a f ly, Delia may be swelling around the infected ■ Control Check vulnerable plants spores are spread readily by water splash radicum, which has three generations site. As the canker enlarges, it may girdle during the summer; spray apples, pears, and air currents, and persist from year between mid-spring and early fall. The the shoot, causing dieback of growth and strawberries with deltamethrin at to year in the soil, or on plant debris, eggs are laid in the soil near the base of above it. Any infected fruits rot before petal fall. as sclerotia. the host plant. maturity. In summer, the canker may ■ Control Good hygiene is the first line ■ Control Established plants usually host raised white pustules, and in winter, Carrot fly of defense as control of such a widespread tolerate infestations, but transplanted red fruiting bodies appear. fungus is difficult. Clear away all plant seedlings are especially vulnerable. ■ Causes The bacterium Pseudomonas ■ Crops affected Carrot, parsnip, debris promptly. Remove dead and There are no insecticides approved for mors-prunorum (on plum and sweet parsley, and celery. injured plant parts before infection sets the amateur gardener to control this pest, cherry) and P. syringae (on peach, apricot, ■ Symptoms Roots are tunneled by in. Remove infected tissues from live but covering seed rows and transplants cherry, and plum). The fungi Neonectria slender, creamy white maggots, up plants as soon as seen, cutting back into with horticultural f leece will exclude galligena (on apple and pear) or Gibberella to 1⁄2in (9mm) long. They leave rusty clean, healthy growth. There are no egg-laying f lies. Alternatively, for baccata (on mulberry), infect mainly in brown lines on the outside of the roots fungicides currently available to transplanted seedlings, prevent the f lies spring. (See also Mulberry canker, p.258.) where tunnels close to the surface have gardeners to control this disease. from laying their eggs by positioning collapsed (see p.250). Damaged roots a collar or disk of carpet underlay, Bacterial infections occur most rot in store. Brown rot cardboard, or roofing felt, approximately commonly in wet, windy weather in ■ Cause Larvae of the carrot f ly, Psila 4in (10cm) in diameter, around the plant fall, or in damp conditions in spring, rosae, which produces three generations ■ Crops affected Tree fruits. base at transplanting time. The females when soft young growth is most between late spring and early fall. ■ Symptoms Soft brown areas develop deposit eggs on the disk, rather than in vulnerable. Spring infections usually ■ Control Fleece or ultra-fine netting on skins of fruits, the f lesh deteriorates, the soil, and they perish before hatching. begin on the leaves and spread to the barriers prevent female f lies from laying and the rot spreads rapidly to the whole bark. Most bark infections enter through their eggs. Carrots sown after late spring fruit. Raised, creamy white pustules Cabbage worm: see Whitef ly. wounds caused by pruning, frost crack, will miss the first generation and those appear on infected areas, and are or leaf fall. Summer infection is rare. harvested before late summer will miss apparent as concentric rings. Fruits may Calcium deficiency the second. Choose cultivars with some become mummified, remaining on the Fungal spores are wind-borne and resistance, such as ‘Flyaway’, ‘Resistaf ly’, tree, or may fall; in both cases, they will ■ Crops affected Various. enter through leaf scars, pruning or or ‘Sytan’. There are no approved form a source of reinfection. ■ Symptoms Shoots and young leaves insect wounds, frost crack, or scab chemical controls available for ■ Causes The fungus Monilinia fructigena often grow poorly, curl, and they infections (see also Apple and pear garden use. on most types of fruit. M. laxa mainly on generally deteriorate. Symptoms are scab, p.251). plums. The fungus gains entry via various, depending on plant and plant ■ Control Prune out areas affected by Caterpillars wounds, such as bird pecks, frost cracks, part affected. bacterial canker during the summer. codling moth exit holes, and scab ■ Brassicas: Internal browning of Spray infected cherries and plums with ■ Crops affected Various. infections; any wound will predispose Brussels sprout buttons and cabbage copper oxychloride or Bordeaux ■ Symptoms Most caterpillars feed plants to infection. Spores are spread hearts. mixture, once at the end of summer, and on leaves, as with cabbage white by birds, insects, rain splash or by direct ■ Carrots: Root cavities. once in early and mid-fall. There are no butterf ly larvae. Ragged holes are left contact with a source of infection. ■ Celery: Blackening of central leaves. preparations for bacterial canker on other in leaves, and a black frass (excrement) ■ Control Take all precautions against ■ Lettuce: Tip burn (see p.263). stone fruits, but copper-based fungicide may remain; the culprits are often found possible injuries. Control insect pests, ■ Potato: Rolled leaves and spindly for control of peach leaf curl gives some on or beneath the leaves. Some attack net against birds, remove infected and shoots. protection. roots, while others bore into stems, feed fallen fruits promptly, and prune out ■ Causes Calcium may be deficient in inside leaves as leaf miners, or feed on mummified fruits, along with a short the soil or compost, or be unavailable for The cherries ‘Merton Glory’, ‘Merton fruits and berries. section of their spur, and destroy by uptake by very dry or acidic conditions Premier’, ‘Merla’, and ‘Merpet’ have ■ Causes Caterpillars are the larval burning. Spray with difenoconazole on in the growing medium. some resistance, as do plums ‘Marjorie’s stage of moths and butterf lies. They cherries, plums, gages, and damsons. ■ Control Keep plants well watered Seedling’ and ‘Warwickshire Drooper’. vary in size, color, and hairiness, but and mulch to retain soil moisture. If are generally long and tubular in form Brown scale possible, lime acid soils to raise the pH. If the cankers are fungal, prune out with a distinct head. They have three See also Bitter pit, Blossom end rot. entire infected spurs or branches where pairs of jointed legs at the head end ■ Crops affected Many tree and bush possible. On larger branch or trunk and two to five pairs of clasping legs fruits, including fig, grape vines, peach, Cane spot infections, carefully pare away all on the abdomen. nectarine, apricot, and plum. infected material, cutting back to ■ Control Some caterpillars are easily ■ Symptoms Shell-like, convex, brown ■ Crops affected Blackberry, raspberry, clean healthy tissue. Spray with copper removed by hand and, as most are scales, up to 1⁄4in (5mm) long, appear and hybrid berries. oxychloride or Bordeaux mixture and night feeders, can be found easily by on stems of infested plants. Sooty molds ■ Symptoms Lens-shaped, purple or treat the wound with a proprietary f lashlight. They can be sprayed with grow on leaves that are sticky with brown-purple spots that have silver-gray wound dressing. Dispose of prunings deltamethrin, pyrethrum, or lambda- honeydew. Infestations are most common centers appear on the canes, sometimes carefully, preferably by burning. Improve cyhalothrin as soon as the plants show in warm, sheltered sites; on plants that spreading to leaves and f lower stalks. As cultural conditions, especially poor signs of caterpillar feeding. are trained against warm walls or grown spots enlarge, canes may split and die. drainage; wet soils increase susceptibility. See also Codling moth, Cutworm, Pea in greenhouses, for example. ■ Cause The fungus Elsinoë veneta, Avoid growing apple cultivars known moth, Plum fruit moth, Winter moth. ■ Cause Parthenolecanium corni, a sap- which is most active in early summer. to be vulnerable, such as ‘Cox’s Orange feeding insect, which lays its eggs ■ Control Prune out infected canes as Pippin’, ‘James Grieve’, ‘Worcester Celery fly: see Celery leaf miner. beneath the scale. There is one soon as seen. Avoid growing susceptible Pearmain’, and ‘Spartan’. The apple generation a year. cultivars, such as raspberry ‘Lloyd cultivars ‘Laxton’s Superb’, ‘Newton Celery leaf miner ■ Control Spray deciduous fruit George’ and ‘Norfolk Giant’. Spray Wonder’, ‘Bramley’s Seedling’, and trees and bushes with a plant oil winter affected loganberry and raspberry plants ‘Lane’s Prince Albert’ show a degree ■ Crops affected Cellery root, celery, wash to target overwintering nymphs. with copper oxychloride. of resistance. Sprays for apple scab and parsnip, lovage, and parsley. Deltamethrin or lambda-cyhalothrin are apple powdery mildew give a degree of ■ Symptoms Leaves develop desiccated approved for summer treatment of scale Canker incidental control. brown patches where the interior has insect on some fruits. been consumed by one or more white See also Scale insect. ■ Crops affected Tree fruits. Canker of parsnips: see Parsnip canker. maggots, each measuring up to 3⁄8in ■ Symptoms: bacterial canker affects (7mm) long. If infestations are severe, Bud drop: see Drought. cherry, plum, apricot, peach, and Capsid bug the plants have a scorched appearance, Bulbous or blown fruits: see Poorly nectarine crops. Clearly defined areas and in celery, the stems develop an formed fruits. of bark f latten and sink inward, and ■ Crops affected Apple, gooseberry, unpleasantly bitter f lavor. amber-colored resin may ooze from the currants, pear, plum, and strawberry. ■ Cause The larvae of the leaf-mining Cabbage root fly bark, especially when injured. Buds at ■ Symptoms Leaves at the shoot tip f ly, Euleia heraclei. There are two the branch tips fail to open and leaves are misshapen and full of small, ragged generations a year, causing damage ■ Crops affected Brassicas, including may wither and die back. Leaves on holes; shoot tips may be killed. Growth between late spring and late summer. rutabaga, turnip, and radish. affected limbs may be small and emerging from affected buds is distorted. ■ Control If infestations are light, pick ■ Symptoms Plants wilt readily on yellowed, and often have holes in them. Developing apples may have irregular off affected leaves by hand. There are sunny days and growth is slow. Seedlings ■ Symptoms: fungal canker affects bumps on their surface and strawberry no chemical controls approved for use die shortly after transplanting. Legless apple, pear, and mulberry crops. Areas of fruits may also be distorted. by amateur gardeners. white maggots, to 1⁄2in (9mm) long, eat bark sink inward, usually starting near a ■ Cause The common green capsid the finer roots, leaving a rotting stump. bud or wound. Bark becomes discolored bug, Lygocoris pabulinus. It is pale green, Cherry slugworm: see Pear and cherry Maggots may also bore into swollen then shrinks and cracks, forming about 1⁄4in (6mm) long. Other species slugworm. roots of radishes, turnips, and rutabagas. concentric rings of f laky bark, and there cause similar damage. These sap-sucking insects inject toxic saliva into the shoot tips, killing plant cells. They are active between late spring and late summer but are very elusive and f ly away when disturbed.

254 A–Z OF PLANT PROBLEMS Chlorosis ‘Marian’. Maintain good weed control; ■ Symptoms Bright coral-pink or aphids and clearing weeds, which may be weeds such as charlock, shepherd’s purse, orange raised pustules appear on dead alternative hosts. Do not handle healthy ■ Crops affected Various. and wild radish are alternative hosts for woody stems or branches. They may plants after touching infected material ■ Symptoms Yellowing of leaves clubroot. Avoid spreading spores around not arise until the tissue has been dead without washing hands first. Resistant primarily, but also other plant tissues. the garden on boots and tools, and do for several weeks. Dieback occurs, and cultivars include eggplant ‘Bonica’; Yellow, red, or orange coloration may not transfer potentially infected soil to if the infection spreads down into the zucchini ‘Defender’, ‘Supremo’, and also develop. The primary symptom other parts of the garden. crown, the whole plant may die. ‘Tarmino’; cucumbers ‘Bush Champion’, is due to the loss or deterioration of ■ Cause The fungus Nectria cinnabarina. ‘Crispy Salad’, ‘Jazzer’, ‘Petita’, and chlorophyll; this green pigment usually Codling moth It lives on dead twigs, old pea sticks, ‘Pioneer’; marrows ‘Badger Cross’ and masks other natural pigments and its logs, and other woody debris, and it ‘Tiger Cross’. loss reveals them. ■ Crops affected Apple and pear. produces spores throughout the year. ■ Causes Most commonly deficiencies ■ Symptoms In mid- to late summer, They are spread in water splash. Infection Currant reversion: see Reversion disease. of iron and manganese (so-called fruits are tunneled by small, brown- gains entry through wounds or dead lime-induced chlorosis), nitrogen, headed white caterpillars. By ripening snags left after pruning and may then Cutworm or magnesium. It can also be caused time, the caterpillars have tunneled to colonize living tissue, causing dieback. If by viruses and unfavorable cultural the core and the fruits are inedible; left unchecked, the whole plant may die. ■ Crops affected Root vegetables, conditions, such as waterlogging, exit holes may be seen at the eye end ■ Control Prune out infected tissue brassicas, lettuce, and leek. low temperatures, or weedkiller (opposite stalk) of the fruit (see p.250) promptly, cutting back to healthy, living ■ Symptoms Young plants wilt and contamination. or elsewhere on the fruit surface. wood. Remove and burn infected tissue. die. Examination of the roots reveals ■ Control Take appropriate action to Damage is similar to—but less extensive Maintain good hygiene to remove all that they have been severed just below remedy nutrient deficiencies, remove than—apple sawf ly (see p. 251), but potential sources of infection. soil level. Root vegetables may have sources of viral contamination, and codling moth is more common. cavities eaten into them. Creamy brown ameliorate poor cultural conditions. ■ Cause The larvae of the codling Corn smut or greenish-brown caterpillars, up to See also Iron deficiency, Magnesium moth, Cydia pomonella. Females lay their 11⁄2in (4cm) long, may be found in the deficiency, Manganese deficiency. eggs on fruits on warm nights in early ■ Crops affected Corn. soil near affected plants. They may also to midsummer. Larvae hatch two weeks ■ Symptoms Individual kernels on feed on foliage above soil level at night. Chocolate spot later and tunnel into the fruit at the eye the cob become greatly enlarged and ■ Causes Soil-dwelling caterpillars end, leaving no visible entry holes. After deformed. Each kernel turns pale gray of several moths, including the large ■ Crops affected Fava bean. feeding, they leave to spin cocoons under and ruptures to release large quantities yellow underwing (Noctua pronuba), ■ Symptoms Chocolate-brown spots f lakes of bark; most overwinter, but of powdery black spores. In wet weather, lesser yellow underwing (N. comes), on upper leaf surfaces, and brown some pupate in late summer to produce these may be carried in rainwater, turnip moth (Agrotis segetum), heart streaks on stems, pods, and f lowers. a second adult generation in early fall. forming a black liquid that run down and dart (A. exclamationis), and garden The seed coats may also be affected. ■ Control Pheromone traps attract the plant. Leaves and stems are only dart (Euxoa nigricans). Severe infections may kill plants and males, reducing the mating success of occasionally affected; the fungus is not ■ Control Cutworms will work their even mild cases can reduce yield. females and the incidence of maggoty systemic, so healthy and infected cobs way along seed rows. Sifting the soil ■ Causes The fungus Botrytis fabae. It apples. Timing of chemical treatments may develop on the same plant. near a damaged plant may reveal the is most prevalent when the air is damp is critical, because it is vital to destroy ■ Cause The fungus Ustilago maydis. culprit. Good weed control reduces and humid. The fungus overwinters on larvae before they enter the fruit; Spores are carried on air currents and the incidence of these pests. Insecticides plant remains and may be seed-borne. pheromone traps indicate when adults in rain splash, and they may infect the for use against these pests are no longer ■ Control Grow beans in well-drained are active and likely to be laying eggs. plants directly or persist in the soil. It available to the amateur gardener. soil. Space the plants more widely than Spray with deltamethrin or lambda- is most prevalent during hot summers. at the usual recommended spacings— cyhalothrin in early summer, with a ■ Control None available. Remove Damping off more than 9in (23cm) apart—to permit second treatment three weeks later. affected cobs before the swollen kernels thorough air circulation around the rupture. Remove and burn all infected ■ Crops affected All seedlings are plants. Maintain good weed control Colorado potato beetle plant debris at the end of the season. vulnerable, including mustard and cress. between rows to minimize local Do not grow corn on the same site for ■ Symptoms Seedlings f lop over, often humidity and any damp air around ■ Crops affected Eggplant, potato, at least five years. showing dark discoloration at the stem plants. Avoid the use of high-nitrogen pepper, and tomato. base, which may appear water-soaked. fertilizers, which will encourage soft, ■ Symptoms Foliage is eaten by pale Crown rot The infection spreads rapidly and clumps infection-prone growth; sulfate of yellow-orange beetles, up to 1⁄2in (1cm) of seedlings die off; whole trays of potash will help to harden the plant long, with five black stripes on each ■ Crops affected Rhubarb, apple, seedlings can be killed within a few days. tissues slightly. wing case. Rotund, orange-red grubs, strawberry, and citrus fruits. Any ungerminated seeds may also fail with black heads and two rows of black ■ Symptoms Rotting of tissues at the to appear. A fuzzy, white fungal growth Clubroot spots along the sides of their bodies, plant crown, the junction between stem appears on the surface of dead and also eat the foliage, causing extensive and roots. Rot may spread to stems and dying seedlings. ■ Crops affected Brassicas, including defoliation. foliage and the plant can die. ■ Causes Several soil-borne fungi, in radish, sea kale, rutabaga, and turnip. ■ Causes Adults and larvae of the ■ Causes Various soil- and water-borne particular, Pythium, Phytophthora, and ■ Symptoms Swollen roots and a Colorado potato beetle, Leptinotarsa fungi and bacteria, often in combination Rhizoctonia species. They proliferate distorted root system (see p.250) with decemlineata. It originated in North (rhubarb). Phytophthora species affect in overwet compost and in prolonged pale, chlorotic foliage. Plants wilt America but can now be found many plants. high temperatures. The most common readily especially in hot weather, even throughout Europe, except in Britain ■ Control Prompt action may save the reason for damping off is sowing seed if the soil is moist. Crops are reduced and Ireland. plant. Remove affected areas by cutting too thickly, causing overcrowding, and and plants may die. ■ Control Insecticide-resistant strains well back into healthy tissue. See also inadequate light. It is also encouraged ■ Cause A soil-borne slime mold, of this beetle occur. Infested plants can Phytophthora. by poor hygiene. Unsterilized compost, Plasmodiophora brassicae. It can live be sprayed with an approved pesticide pots, trays, and implements, and in soil for 20 years or more, even when adults or larvae are seen. Cucumber mosaic virus water from a rain barrel may all be without a host. Infection enters contaminated with fungal spores. through the root hairs, and when the Copper deficiency ■ Crops affected Various, including ■ Control Observe strict hygiene; scrub roots disintegrate, they release spores eggplant, but especially cucurbits. all pots, trays, and implements before into the soil. The pathogen can be ■ Crops affected Various. ■ Symptoms Plants and leaves are use and use only proprietary, sterilized introduced to gardens in soil that adheres ■ Symptoms Yellowing of leaves or stunted and deformed, and leaves show seed composts. Use only tap water for to boots, tools, and wheelbarrows, in blue-green discoloration is occasionally distinctive yellow mosaic patterning watering. Sow seedlings thinly and make garden compost or manure, and directly followed by dieback (see below). Symptoms (see p.250). Flowering is reduced or sure that they have good light and are on infected plants. It is most common are rather vague and difficult to nonexistent, and plants may die not exposed to high temperatures for on acid and waterlogged soils. distinguish from many other problems. completely. In cucumbers, zucchini, longer than is needed for germination. ■ Control Improve drainage and ■ Cause Copper deficiency is and winter squash, the fruits, if produced Drench the compost with a copper-based lime the soil. Burn all infected plants uncommon but most likely to occur on at all, are small, pitted, and unusually fungicide before sowing. Treat seedlings promptly, before roots disintegrate. acid soils. dark green with bright yellow patches; with the same fungicide during their Raise your own rather than buy plants, ■ Control Treatment with a general they are also hard and inedible. early development. in 2in (5cm) pots or larger, so their compound fertilizer (see p.20) may help. ■ Causes The cucumber mosaic virus root systems are well established has a very wide host range and can be Deer before setting out. Otherwise, buy Coral spot canker spread to crop plants on the mouthparts from a trusted source and check plants of aphids and other sap-sucking insects. ■ Crops affected A wide range. thoroughly before planting. Choose ■ Crops affected Currant and fig crops ■ Control Destroy infected plants; there ■ Symptoms Whole shoots and f lowers resistant cultivars, like calabrese are most susceptible, but many different are no chemical controls available. are eaten; on woody stems the damage ‘Trixie’, Chinese cabbage ‘Harmony’, woody plants can be affected. Reduce risk of infection by controlling is very characteristic. Since deer have kale ‘Tall Green Curled’, and rutabaga

A–Z OF PLANT PROBLEMS 255 no front teeth in their upper jaws, they ■ Control Remove infected leaves as usually scattered throughout the crown; sterilized composts and water from cut off stems by biting and tugging. soon as seen. Improve air circulation healthy stems may coexist with infected a faucet for irrigation. This gives a clean-edged cut part way around plants by maintaining good ones. The bark sinks inward on young through the stem, and a ragged edge weed control and planting at wider than stems, and if pared back, a foxy-red Frit fly on the remainder where the shoot has usual spacings. Keep greenhouses well discoloration is seen on the wood. been tugged away. Tree trunks and ventilated. Avoid overhead watering. Bacterial ooze may exude from affected ■ Crops affected Corn. side-branches may also be damaged by There are no fungicides available to areas. The symptoms are similar to those ■ Symptoms Longitudinal yellow fraying—the habit that male deer have amateur gardeners for the control of of blossom wilt (see p.252). stripes appear on young leaves, which of rubbing their antlers against the bark downy mildew. ■ Cause The bacterium Erwinia later deteriorate, fraying into strips. to remove the velvet. amylovora. It is most prevalent in warm, Plants fail to thrive and crops are ■ Causes Several species of deer cause Drought wet weather. It usually enters through diminished. In severe infestations, problems in gardens: roe deer (Capreolus open blossoms, but it can also gain entry growing points are killed, and plants may capreolus), fallow deer (Dama dama), ■ Crops affected Various. through stem injuries. It may be carried die. Small white larvae, 1⁄4in (5mm) long, muntjac (Muntiacus muntjak), and red ■ Symptoms Symptoms vary according in water splash and spread on pruning may be found feeding in the stems and at deer (Cervus elaphus). to crop and whether the drought is tools. the base of leaves in midsummer. ■ Control These agile creatures can be recurrent, continuous, or occasional. ■ Control Prune out affected stems to ■ Cause Larvae of the f ly Oscinella frit. very difficult to exclude from gardens, Poor growth and stunting occurs if at least 2ft (60cm) into healthy wood. Adults lay eggs in early summer, at or since they are incorrigible leapers of drought is recurrent or continuous; Dispose of all prunings by burning, near the base of the plant. Larvae hatch fences. A fence of at least 6ft (2m) in foliage wilting is the first sign of dry and sterilize all tools after use. If the two or three weeks later, entering the height is needed to keep out roe deer. conditions. If prolonged, drought may infection is widespread, or the tree stems to feed. There may be three They are also inquisitive feeders and cause poor f lowering, bud or fruit drop, is small, it may be best to remove it generations between early summer and new plantings are particularly attractive and the formation of small, poor quality entirely. If planting ornamental plants fall; the last overwinters as larvae in to them. It is worthwhile giving newly fruits. Drought followed by high rainfall near susceptible crops, avoid those that grasses and cereal crops. planted trees the protection of individual or sudden watering may cause splitting of might be a source of infection (see above). ■ Control Maintain good weed control, cages. Proprietary repellents usually give fruits and stems. The risk of fireblight is low in most especially of grasses. Provide good disappointing results; their effects tend ■ Causes Inadequate rainfall or years, so gardeners with hawthorn growing conditions so that plants to be short-lived and frequently have the watering is the most obvious cause. hedges should keep them. There is establish rapidly; well-established plants unwanted effect of encouraging feeding Occasionally, it results from root damage no effective chemical control. are less vulnerable to attack. Raise in other areas of the garden. that prevents uptake of sufficient water. seedlings singly in pots under glass and Plants in containers or with restricted Flea beetle plant them out after the early summer Dieback root runs are especially vulnerable, as egg-laying period to avoid this pest. are those on light, freely draining, sandy ■ Crops affected Potato, brassicas, There are no approved chemical controls ■ Crops affected Woody-stemmed or chalky soils. rutabaga, turnip, sea kale, radish, and available to amateur gardeners for frit f ly. crops, such as tree and bush fruits. ■ Control Water consistently and rocket. ■ Symptoms Plant stems die back, regularly to prevent soil from becoming ■ Symptoms Small, shiny black beetles, Frost damage usually from the tip, but often from completely dry. Take all steps to improve sometimes with yellow-striped wing (buds and flowers) the base, or sometimes partway up the the soil’s moisture retention by cases and usually about 1⁄12in (2mm) stem. Dieback rarely affects all stems incorporating plentiful organic matter long, leap from affected foliage when ■ Crops affected Various, especially simultaneously. Dark blotches or sunken and by mulching. Protect container- disturbed. Some species are larger, to bush and tree fruits. patches may develop at the initial point grown plants from the desiccating effects 1⁄6in (4mm), and are metallic blue or ■ Symptoms Buds, whether tightly of infection. Leaves wilt, turn yellow, of direct sunlight and consider using yellow-brown in color. They eat small closed or partially open, become and die. If unchecked, the symptoms water-retaining gels or granules in the round holes in the upper leaf surfaces discolored. They turn brown and often spread down the stem, finally to the growing medium. (see p.250), seldom penetrating the leaf become soft and squidgy to the touch. base or crown, causing death of the entirely. Damaged tissues desiccate and Buds on more exposed areas of the plant whole plant. Edema turn pale brown. Heavy attacks may are the worst affected. Damage may only ■ Causes Various fungi, some of kill seedlings and check the growth of occur at certain developmental stages of which are wound-invading pathogens, ■ Crops affected Various, but grape established plants. the bud or f lower, so on any given plant, while others can affect formerly vines are particularly vulnerable. ■ Causes There are many species of some will escape injury. Nevertheless, healthy stems. Root infection by soil- ■ Symptoms Raised, wartlike growths f lea beetle. Brassicas are most usually there will be a subsequent loss of the dwelling pathogens, such as honey appear, most often on lower leaf surfaces, affected by Phyllotreta species; potatoes fruit crop to a greater or lesser degree. fungus (see p.256) or phytophthora but sometimes on grapes. They are leaf- suffer most often from Psylliodes affinis. ■ Causes Freezing causes extensive (see p.259), can also cause stem colored at first, but may become brown Adults damage the foliage while the soil- cell damage; cells are ruptured as the dieback in woody plants. It may be and corky. Affected leaves may become dwelling larvae feed on roots. Adults are frozen cell contents expand. This is also be caused by unfavorable cultural distorted, but death is not inevitable. active in mid-spring and late summer. exacerbated when thawing is rapid. conditions, especially where dieback ■ Causes A cultural condition whereby ■ Control Sow when growing Slightly tender plants and early f lowering occurs from the stem tip downward. leaves take up more water than is lost conditions are good, so that seedlings cultivars are most vulnerable, but late These include drought, waterlogging, by transpiration. Small groups of cells can germinate and grow rapidly through frosts, which often occur unpredictably and poor establishment of newly planted become waterlogged, swelling to form the vulnerable seedling stage. Protect after the f lower buds have opened, can trees and bushes—if watering has been blisterlike, pale green warty growths. seedlings and young plants with be particularly damaging. neglected, for example. If conditions do not improve, the cells horticultural f leece or similar barriers. ■ Control Choose planting sites with ■ Control Prune out affected stems back rupture and die, turning brown and If necessary, spray seedlings with care. Avoid known frost pockets and to healthy growth. Improve cultural corky. The condition is most common deltamethrin or lambda-cyhalothrin. sites where plants will receive direct conditions to increase plant vigor and when humidity is high and water levels early morning sun, if possible. Protect ensure plenty of replacement shoots. at the roots are excessive. Foot and root rots more tender plants, such as peaches and ■ Control Avoid overwatering, improve nectarines, by growing against a warm, Downy mildew drainage, and ventilate crops under glass. ■ Crops affected Asparagus, celery, sheltered wall and cover with f leece or Space plants more widely than the tomato, cucurbits, melon, pea, bean, similar when frost threatens. In cold ■ Crops affected A wide range. recommended distances to permit good and greenhouse and soft fruits. areas, choose later f lowering cultivars. ■ Symptoms Discolored or yellowed air circulation. Do not remove affected ■ Symptoms Infections at the stem areas appear on upper leaf surfaces, with leaves—this exacerbates the problem. base cause tissues to darken, atrophy, Seek out local cultivars of tree and corresponding slightly fuzzy, pale gray and soften. The upper parts respond bush fruits; these are generally older or purplish fungal growth beneath each Fireblight by wilting, discoloring, and dying cultivars that have been selected to suit patch (see p.250). As the infection back. Root rotting may occur at the prevailing climatic conditions and are spreads, large areas or even entire leaves ■ Crops affected Pome (applelike) fruit same time. most likely to be available from specialist die. Downy mildew is most commonly crops of the family Rosaceae, including ■ Causes Various fungi, often those local nurseries. found on young plants and on those apple, pear, quince, and medlar. Many responsible for damping off (see facing growing in damp environments. It can ornamental plants are affected, notably page). Other fungi, including fusarium Frost damage be difficult to distinguish from powdery amelanchiers, cotoneasters, hawthorns, and verticillium (see pp.256, 263) may (foliage and stems) mildew (see p.260), which is more photinias, pyracanthas, and sorbus; these cause both wilting and foot rot prevalent in dry conditions. plants may be a source of infection. symptoms. ■ Crops affected Various leafy crops, ■ Causes A range of fungi, mostly ■ Symptoms Flowers wilt, wither, and ■ Control There is no cure for infected including early potato crops. Peronospora, Bremia, and Plasmopara die back, followed shortly by adjacent plants. Prevent the spread of the disease ■ Symptoms Leaves, usually toward species. Some are specific to their host: leaves and stems. Plants may show by immediate removal of affected plants, the shoot tips, and on other exposed Peronospora parasitica on brassicas, P. extensive dieback and are killed within along with the soil or compost at their parts of the plant, appear scorched and destructor on onion, P. farinosa f. spinaceae a few seasons. Infection occurs most roots. Maintain impeccable hygiene, turn brown or black. Affected parts on spinach, Bremia lactucae on lettuce, commonly at f lowering time and is washing pots, trays, and implements may wilt, wither, and die, and young and Plasmopara viticola on grape vines. thoroughly before use. Use only stem growth adjacent to frosted leaves

256 A–Z OF PLANT PROBLEMS may also die back. Occasionally, isolated Fusarium wilt lesser gooseberry sawf ly (N. leucotrochus), plants that have root wounds or are patches of damage occurs on otherwise and pale gooseberry sawf ly (Pristiphora otherwise stressed. Without laboratory sound stems. ■ Crops affected Various, both woody- appendiculata). identification, it can be difficult to ■ Causes Freezing causes extensive and soft-stemmed. Pea crops are ■ Control Inspect gooseberry and differentiate between the species, except cell damage in plant tissue; cells are commonly affected. currant bushes carefully from mid- on the basis of the damage they cause. ruptured as the frozen cell contents ■ Symptoms Soft stems wilt, in part spring onward; examine leaf undersides, Spread occurs either by direct root expand. This is exacerbated when or in their entirety, while woody- especially in the center of the bush. contact or by rhizomorphs, which can thawing is rapid, as it is when crops stemmed plants may retain their overall Infestations commonly begin at grow at a rate of up to 3ft (1m) per year. are exposed to direct early morning shape, but leaves on affected parts wilt the heart of the bush and the pest ■ Control Keep plants in good health sun. Slightly tender plants, overwintering and wither. The decisive symptom is defoliates upward and outward, causing by good cultivation, keeping them well and early crops are most vulnerable, brown or black staining on the internal considerable damage before being fed, mulched, and watered. Avoid root but late spring frosts, which often vascular tissue, which is apparent noticed. Spray affected plants with damage when cultivating the soil around occur unpredictably, can be particularly beneath the bark or at the root core. pyrethrum or lambda-cyhalothrin as plants. Honey fungus will infect more damaging. Plant death is almost inevitable. In cool, soon as the larvae are discovered. readily plants that are stressed, for ■ Control Choose planting sites damp conditions, f luffy, pale pink, or example by drought, excessive pruning, carefully, especially for crops known white fungal growth may be visible Gray mold: see Botrytis. or severe pest infestations. Remove all to be easily frost-damaged. Avoid on infected tissues. dead trees from the garden, including known frost pockets and sites that ■ Causes Various strains of the fungus Halo blight their roots, regardless of their cause of receive direct morning sun when Fusarium, most commonly F. oxysporum, death, since dead woody tissues are a possible. Protect vulnerable crops, cause fusarium wilt. The fungi are often ■ Crops affected Dwarf French and prime food source for honey fungus. It such as early potatoes, with horticultural host-specific, but all are responsible runner bean. is imperative to remove as much of the f leece or similar. With potatoes, for blocking the vascular tissues with ■ Symptoms Small, angular spots root system of infected plants as possible; earthing up helps to reduce damage. gumlike substances, which cause appear on the foliage, at first appearing hire a stump grinder if necessary. An fall dressing of sulfate of potash wilting in much the same manner water-soaked and then darkening in helps to harden stem growth and may as drought. Unlike plants suffering color; each spot is surrounded by a Iron deficiency minimize damage to overwintering from drought, however, those affected bright yellow “halo.” The leaves begin crops, such as sprouting broccoli. by fusarium wilt do not recover when to turn yellow between the veins and ■ Crops affected Many, including watered. The fungus persists in plant eventually the entire leaf is affected apple, pear, blueberry, raspberry, and Fruit fly debris and is also capable of surviving and dies. Growth and yields can be blackberry. in the soil, in the absence of a host, seriously affected. If stems or pods are ■ Symptoms Leaf yellowing, or ■ Crops affected Apple, cherry, citrus, for several years. infected, they develop gray patches, chlorosis (see p.254), between the leaf passion fruit, peach, plum, olive, melon. ■ Control Remove infected plants again with a water-soaked appearance. veins, often in combination with brown ■ Symptoms Fruit f lesh is infested promptly to minimize spread and ■ Cause The bacterium Pseudomonas discoloration that starts at the leaf with small white maggots, which destroy, preferably by burning. Do syringae pv. phaseolicola, which is spread margins and moves in toward the veins. sometimes cause galls. Adult insects, not put them on the compost heap. by water splash and is carried by seeds— Young growth is affected earlier and up to 1⁄4in (6mm) long, have red-orange Where practicable, remove soil or usually the initial source of infection. more severely than older growth. heads, black bodies marked yellow compost from the immediate vicinity ■ Control Pick off infected leaves as ■ Causes Iron deficiency is usually and white, and mottled wings. They of the roots. Do not grow the same or soon as seen and avoid overhead seen in combination with manganese resemble tiny house f lies and may be closely related plants on the same site watering. Remove and burn all affected deficiency (see facing page). It is most seen on or f lying around plants. again, or for a minimum of five years. plants at the end of the season and do common in acid-loving plants, such ■ Cause Many species, including There is no chemical cure. not store the seed. The dwarf French as blueberries, when grown on limy Ceratitis capitata. They are native to bean cultivars ‘Forum’ and ‘Red Rum’ (alkaline) soils; hence the term lime- Mediterranean and subtropical regions, Gall mites: on black currant, see Big bud show some resistance to this infection. induced chlorosis. It can also affect but they do not occur in some cooler mite; on pears, see Pear leaf blister mite. other plants that are not noted as being climates. The f lies breed throughout Ghost spotting: see Tomato ghost spot. Honey fungus acid-lovers. A shortage of soil iron the year where temperatures permit and is rare, but iron (and manganese) can are serious fruit pests in warmer parts Gooseberry dieback ■ Crops affected Tree and bush fruits, be rendered unavailable to plants if of the world, but not in cool-temperate strawberry, rhubarb, and artichoke. Most soils are too alkaline; the mechanism climates, such as the colder parts of ■ Crops affected Gooseberry and, less woody plants are susceptible. is complex but, in brief, the excess North America. commonly, black currant. ■ Symptoms Affected plants begin to calcium “locks up” the iron in the soil, ■ Control Yellow sticky traps and ■ Symptoms Dieback of stems. Usually die back, leaves may discolor and wilt, so that plants cannot absorb it. pheromone traps help reduce populations, only some of the stems are affected, but or trees may fail to leaf up in spring. ■ Control Do not grow acid-loving the latter by foiling the reproductive the infection occasionally spreads; if the Death can be rapid or drawn out over plants on soils that are not sufficiently success of females by attracting and main stem or base of the plant is affected, several seasons. Fruit trees may set an acidic. Treat affected tree, bush, and trapping male f lies. Food lure traps the entire bush will die back. In damp unusually good crop before dying. The soft fruits with a chelated compound attract both sexes of the f ly. Chemical weather, fuzzy, gray fungal growth is roots and stem or trunk bases develop containing iron, manganese, and other treatments should be targeted at adult seen around damaged areas. Leaves on a white fungal sheet, with a decidedly trace elements; these will be in a form f lies, since once inside fruits, larvae infected stems yellow, turn brown, and mushroomlike aroma, between the bark that does not become locked up by are difficult to reach with sprays. Prevent fall prematurely. Any developing fruits and the woody tissues beneath. Around calcium, and they will be available adult f lies from laying eggs by spraying may shrivel and die. the root system in the soil, there may to plant roots. with an approved insecticide at times ■ Cause The fungus Botrytis cinerea be “rhizomorphs,” which resemble black when the adults are seen to be active. (see also Botrytis, p.252). Spores are or brown shoelaces, or old tree roots. Restrict liming on soils that are spread in air currents and in water splash. They can be branched and f lattened already alkaline. If soils are very alkaline, Fruit splitting: see Drought, Splitting. ■ Control Prune out infected shoots or may be plump and more rounded, consider acidifying the soil by using Fruit tree red spider mite: see Red spider promptly, removing all wood that varying in diameter from less than a sulfur or aluminum sulfate and ferrous mite. shows staining or discoloration; cut millimeter to several millimeters across. sulfate before planting. For acid-loving back to a bud on healthy wood. Remove If the black outer rind is stripped off, plants, use an acidic mulch of pine Fusarium basal rot any infected fruits, which form a source it may be lined with pink or white needles or chopped conifer bark; of further infection. fungal growth. The rhizomorphs feed incorporate some in the planting hole ■ Crops affected Bulb onion, green on dead woody material, but may grow before planting. Feed with a fertilizer onion, and garlic. Gooseberry sawfly through the soil to latch onto living formulated for use on acid-loving plants. ■ Symptoms Decay spreads up through tissues. Rhizomorphs may also be found the bulbs from the basal plate. Once ■ Crops affected Gooseberry, red beneath the bark at the base of the stem Leaf blight: of walnuts, see Walnut leaf infected, the plant is effectively dead. currant, and white currant. or trunk of infected plants. In late blight. ■ Cause Several Fusarium species ■ Symptoms Rapid and severe summer or fall, clumps of honey-colored Leaf blotch: of walnuts, see Walnut including the fungus Fusarium oxysporum defoliation occurs, the bush often being toadstools may appear. They cluster blotch f. sp. cepae on onions. Unlike most reduced to bare stems by harvest time. at the base of the plant, or may form Leaf-curling aphid: see Plum leaf-curling other strains of F. oxysporum (see Pale green, caterpillarlike larvae (see colonies that follow the line of the aphid. below), this one does not cause wilting. p.250), up to 3⁄4in (2cm) long, often roots. They are commonly seen infesting Leaf-curling midge: see Black currant gall It is more prevalent in warm-temperate heavily marked with black spots, eat old, dead tree stumps. The stipe or midge. climates. the leaves. Damage starts in mid- to stem of the toadstools usually bears a Leaf miner: see Celery leaf miner. ■ Control Remove and burn infected late spring, but there can be three distinctive creamy white ruff or collar. plants promptly to minimize spread. generations a year, so it may continue ■ Causes Various species of the fungus Leaf spots (bacterial) Do not put them on the compost heap. through the summer. Armillaria. These show varying degrees Practise crop rotation (see p.31). ■ Causes Sawf ly larvae. Three species of ability to cause disease, with some ■ Crops affected Various, including attack gooseberry crops: common being less virulent than others. Less brassicas, cucumber, and mulberry. gooseberry sawf ly (Nematus ribesii), virulent species tend only to infect ■ Symptoms Gray or brown, usually angular or circular necrotic spots appear

A–Z OF PLANT PROBLEMS 257 on leaves, often with a yellow “halo” consider laying a sheet of black plastic show deficiency symptoms first (compare covered in a mealy white wax. During around them. There are no minute, over the area following heavy rain or with iron deficiency, see facing page). early summer, the aphids infest the shoot raised fungal bodies visible, as there irrigation. The larvae will come to the Magnesium is very mobile in the plant tips. The new leaves are distorted when are in fungal leaf spots. surface and can be collected up and and when in short supply it is transferred they emerge and they have a pale mottled ■ Causes Various bacteria may be removed as the plastic is rolled back. from older lower leaves to new ones appearance. If infestations are severe, the involved. Examples include Pseudomonas There are no chemical controls approved nearer the stem tips. shoot tip may be killed and multiple syringae pv. maculicola on brassicas, P. for use by amateur gardeners. ■ Causes Magnesium deficiency is branching occurs as a result. syringae pv. lachrymans on cucumber, and most common in very acid soils or ■ Causes The sap-sucking aphid P. syringae pv. mori on mulberry. They are Leek rust potting composts, and after heavy rain Brevicoryne brassicae. most often spread by water splash, or or watering, especially on light, sandy ■ Control Treat with fatty acids, occasionally from stem lesions to leaves ■ Crops affected Leeks, onions, soils. When water levels are high, deltamethrin, pyrethrum, lambda- (as with bacterial canker, which can cause shallots, garlic, and chives. magnesium is readily leached from the cyhalothrin, or thiacloprid. leaf spots on Prunus species). In most ■ Symptoms Outer leaves develop lens- soil. The excessive use of high-potash cases, the damage is cosmetic, but it can shaped, bright orange, raised fungal fertilizers or sulfate of potash may Mice indicate a plant is under stress or suffering pustules, 1⁄16–1⁄12in (1–2mm) long. When exacerbate this deficiency, because high from another, more serious problem. these erupt, they release conspicuous levels of potassium in the soil can render ■ Crops affected Stored fruits, ■ Control Remove infected leaves masses of bright orange spores. Affected magnesium unavailable to plant roots. vegetables, and seeds; and in the garden, promptly and avoid overhead watering. leaves turn yellow and die back. Inner ■ Control When liming, consider using pea, bean, and corn are especially There is no chemical treatment. leaves are seldom badly affected. magnesian limestone. For more rapid vulnerable to nibbling by mice. ■ Causes Strains of the fungus Puccinia amelioration, apply magnesium as ■ Symptoms Pea, bean, and corn seeds Leaf spots (fungal) allii. The strains that attack leeks do a foliar spray. Apply Epsom salts at a and seedlings are removed and eaten. not attack onions or chives. They are rate of 8oz in 2½ gallons (200g in 10 Stored produce is also eaten during fall ■ Crops affected Beets, blackberry, most prevalent in damp conditions and liters of water), adding a wetting agent. and winter, when mice migrate indoors, celery, currants, Swiss chard, gooseberry, in wet weather. Alternatively, apply Epsom salts to the or raid sheds and outhouses. and raspberry. ■ Control Remove and destroy all soil at a rate 11⁄2oz per sq yd (40g per ■ Causes Mus and Apodemus species, ■ Symptoms Gray or brown, circular affected leaves at harvest. Dispose of sq m) or Kieserite at 21⁄2–5oz per sq yd (house, wood, and field mice) are the necrotic spots appear on leaves; they may all debris thoroughly at the end of the (70–140g per sq m). usual suspects. join together so that large areas of leaves season and grow leeks and other onion ■ Control Set mouse traps in places die. The spots often have concentric family members on a fresh site each Manganese deficiency where mice have caused damage. In the rings of discolored tissue around them year. Avoid the use of high-nitrogen garden, put traps under the cover of logs and often bear tiny, raised, black or fertilizers, which encourage soft, disease- ■ Crops affected Various, including or bricks, away from birds or pets. brown fungal fruiting bodies. prone growth. At planting time, apply pea, bean, brassicas, beets, parsnip, ■ Causes A wide range of fungi, some a dressing of sulfate of potash at a rate spinach, and bush and tree fruits. Humane mouse traps, which trap live of which are host-specific, for example, of 1⁄2–3⁄4oz per sq yd (15–20g per sq m); ■ Symptoms Yellowing develops animals, are only humane if checked at Ramularia beticola and Cercospora beticola this helps harden tissues and improves between the leaf veins (interveinal least twice daily, because these small on beet leaves. Although entire leaves resistance. Space plants more widely than chlorosis) of older leaves, and necrotic creatures are killed easily by starvation, may die, fungal spots are not very usual to improve air circulation and brown patches often appear on the stress, dehydration, or heatstroke. The serious, but they may indicate that the maintain good weed control. Choose yellowed areas. In potato crops, the culprits should be released at least 330yds plant is suffering from some other, more leek cultivars with known resistance, young foliage may be pale and rolled (300m) away from the capture site. fundamental problem. such as ‘Walton Mammoth’, ‘Titan’, upward at leaf margins. Pea and bean ■ Control Remove affected leaves if ‘Poristo’, ‘Poribleu’, and ‘Splendid’. seeds may exhibit almost circular Mint rust needed. At the end of each season, rake brown spots that become visible when up fallen leaves to minimize the numbers Lettuce root aphid the cotyledons are pulled apart. ■ Crops affected Mint, marjoram, and of overwintering spores. Difenoconazole ■ Causes Manganese deficiency, which savor y. can be used to control fungal leaf spots ■ Crops affected Lettuce, chicory, is most common in acid, peaty soils and ■ Symptoms Leaves and stems are on brassicas, cellery root, celery, rhubarb and endive. on poorly drained, sandy soils. It can be distorted and f lecked with yellow; in and asparagus. ■ Symptoms Lettuce plants wilt and induced by an excess of iron in the soil, mint, the stems may be conspicuously make slow growth in sunny weather, but may also occur in tandem with an contorted as they emerge from the Leather jackets even in moist soils. If plants are dug iron deficiency. ground in spring. Cupped, orange fungal up, the roots and surrounding soil will ■ Control Avoid overliming susceptible fruiting bodies develop on the stems ■ Crops affected Many, including be seen to be coated with a waxy white soils. Spray affected plants with a and leaves, later turning yellow-orange, young brassicas, lettuce, and strawberry. powder. Closer examination reveals solution of manganese sulfate at the then dark brown. Seedlings are very vulnerable to attack. creamy yellow aphids, up to 1⁄12in manufacturer’s recommended rate. ■ Cause The fungus Puccinia menthae. ■ Symptoms Plants turn yellow, wilt, (2mm) long, on the roots. See also Chlorosis, Iron deficiency. This overwinters as resting spores in the and may die. The symptoms are similar ■ Cause The lettuce root aphid, soil and within infected rhizomes. to those seen in cutworm damage (see Pemphigus bursarius. This sap-sucking Mealybugs ■ Control The easiest means of control p.254) and in some foot and root rots aphid feeds on outdoor lettuce roots is simply to dig up and burn plants, and (see p.255). The roots are eaten, and during mid- to late summer. ■ Crops affected Most greenhouse to replace them with new ones in spring. sifting the soil around the site of damage ■ Control Keep lettuces well watered plants, including citrus fruits, grape vine, Obtain stock from a reliable source and may reveal legless, gray-brown larvae, and grow them on a different site each pineapple, and prickly pear. plant in a completely new site. It is up to 13⁄4in (4.5cm) long; they have year. Choose cultivars with some ■ Symptoms Soft-bodied, pale gray possible to kill the fungus with a f lame no obvious heads. Most damage is seen resistance, such as lettuce ‘Avoncrisp’, or pink insects, up to 1⁄6in (4mm) long, weeder; burn off the top-growth at the in spring and it is particularly common ‘Avondefiance’, ‘Debby’, ‘Lakeland’, infest stems, usually in inaccessible end of the season and scorch the soil. It on newly cultivated ground that was and ‘Sigmaball’. Insecticides do not places like leaf axils. A f luffy white is difficult to do this safely and reliably previously grassed over. give good control of root aphids. wax is secreted by the insect and this and there is a risk of overdoing it and ■ Causes The larvae of crane f lies, also conceals their eggs. Excretions of killing the plant entirely. or daddy-long-legs. The most common Lime-induced chlorosis: see Chlorosis, honeydew are host to black sooty mold. species are Tipula paludosa, T. oleracea, Iron Deficiency. ■ Causes There are several species of Molybdenum deficiency and Nephrotoma maculata. The adults lay mealybugs that occur in greenhouses; their eggs in the soil in late summer Magnesium deficiency the most common are Pseudococcus and ■ Crops affected Broccoli and and larvae hatch two weeks later. They Planococcus species. caulif lower. feed during the fall and again in the ■ Crops affected Apple, some brassicas, ■ Control A thorough spray with fatty ■ Symptoms Leaves are mottled following spring and summer. There is cherry, grape vine, lettuce, potato, acids or plant oils can be effective, as can yellow and stunted, and they may die usually only one generation a year, but and tomato. hand-picking if done frequently. Where off. Growing tips are often distorted; there may be huge populations following ■ Symptoms Yellowing develops daytime temperatures are 75ºF (24ºC) or this is a typical symptom of molybdenum a warm, damp summer and fall. between the leaf veins (interveinal more, a biological control—the ladybug deficiency, sometimes known as whiptail ■ Control By the time leather jackets are chlorosis) and around the leaf margins, predator Cryptolaemus montrouzieri—can of brassicas. large enough to cause noticeable damage, leaving clear green bands immediately reduce infestations. ■ Causes It is rare that soils are they have become fairly resistant to adjacent to the veins (see p.250). As the deficient in molybdenum, but acid soils insecticides. Biological control, using the green color is lost, other pigments may Mealy cabbage aphid or composts may render this element pathogenic nematode Steinernema feltiae, be revealed, so instead of yellowing, unavailable. It is needed for the is possible, but the soil must be moist and red, purple, or brown discoloration may ■ Crops affected Brassicas and rutabaga. assimilation of nitrogen by the plant, warm (at least 54ºF/12ºC). The larvae occur. Apple crops may be so severely ■ Symptoms Yellow patches appear on hence abnormal cell formation and are a favorite food of starlings, thrushes, affected as to defoliate. Symptoms are the foliage between mid-spring and mid- subsequent check to growth. and blackbirds; turning over the soil in most pronounced toward the end of fall. Beneath the leaves, there are dense ■ Control Increase pH of acid soils by fall can expose the larvae to birds. If the season, and the older leaves always colonies of gray-white aphids, which are liming. Alternatively, drench soil of converting grassland to a vegetable plot, affected plots with ammonium or sodium

258 A–Z OF PLANT PROBLEMS molybdate; dissolve 1⁄8oz (2.5g) in ■ Control Make regular applications be brought in on infected seed or sets. their margins, producing a typically 1 pint (0.5 liter) of water to treat of composts and well-rotted or matured Do not apply fertilizers after midsummer, scalloped effect. They are caused by 1 sq yd (1 sq m). mulch materials, and apply nitrogen-rich and avoid the use of high-nitrogen gray-brown weevils, 1⁄8–1⁄6in (3–4mm) fertilizers. Grow legumes (for example, fertilizers, since they induce soft, long. They may be observed in action, Mulberry canker peas and beans), which are capable of infection-prone growth. Keep crops well but they are elusive, dropping off the fixing nitrogen by means of bacteria in watered and improve cultural conditions plant when disturbed. ■ Crops affected Mulberry. their root nodules. Leguminous green so that firm, well-ripened bulbs are ■ Causes The adult weevil Sitona ■ Symptoms Small cankers girdle manures, such as crimson clover (Trifolium produced. At harvest time, allow onion lineatus, which overwinters in plant the stem causing shoot dieback. Tiny, incarnatum) and winter tares (Vicia sativa), necks to f lop naturally rather than debris and feeds from early spring. reddish-brown pustules arise around will also fix nitrogen in the soil. bending them over to terminate growth; The larval stage feeds on the nitrogen- the cankers and are most noticeable bending can cause wounds that form fixing root nodules of peas and beans. in summer. Nut weevil entry points for disease. When they are ■ Control Plants can withstand the small ■ Cause The fungus Gibberella baccata. drying off prior to storage, protect amount of damage usually caused. If ■ Control Prune out affected shoots and ■ Crops affected Hazelnut and filbert. onions from rainfall in a covered, open, infestations are severe, or small plants are areas of dieback to limit its spread. See ■ Symptoms In late summer, nuts well-ventilated place. Red- or yellow- heavily attacked, spray with deltamethrin also Canker. develop round holes, 1⁄16–1⁄12in (1–2mm) bulbed, rather than white onions, are or lambda-cyhalothrin. Avoid spraying across, in their shells; these are the exit more resistant to infection, as is the plants in f lower to protect bees. Nectria canker: see Canker, fungal. holes of the weevil grubs, which bore cultivar ‘Norstar’. their way out of the nut to pupate in Pea aphid Nematodes the soil. The nut kernel is eaten by a Onion thrips white maggot with a pale brown head. ■ Crops affected Pea. ■ Crops affected Various. ■ Cause The grubs of a weevil, Curculio ■ Crops affected Onion family, ■ Symptoms Young growths are infested ■ Symptoms Generally, nematodes nucum. The adult is about 1⁄2in (1cm) including leek. by large, pale green, pink, or yellow cause distortion, discoloration, and long, with a long slender snout that is ■ Symptoms A fine, white mottling aphids, which cause a check to growth. death of plants. Many are specific plant more than half its body length. develops on onion or leek leaves during ■ Cause The pea aphid, Acyrthosiphon parasites, which cause characteristic ■ Control In most cases, only a small the summer. Black or pale yellow, pisum. This species is a significant carrier symptoms in their host plants. proportion of the crop is affected, so narrow-bodied insects, up to 1⁄12in of a range of viral diseases that have the ■ Causes Nematodes, or eelworms, are routine control measures are unnecessary. (2mm) long, are found on the leaves. potential to affect legumes. mostly microscopic, wormlike creatures. There are no pesticides approved for use ■ Causes The adults and nymphs of a ■ Control Treat with deltamethrin, Not all are pests; many feed on dead by amateur gardeners against this pest. sap-sucking insect, Thrips tabaci. Many pyrethrum, or lambda-cyhalothrin in tissue, bacteria, fungi, and on other ornamental plants are alternative hosts. early summer if aphids are present. microscopic creatures. Some nematodes Olive scab: see Apple, pear, and olive Thrips are most troublesome in hot, dry See also Aphids. are parasitic on garden pests. Slugs and scabs. summers and, while light infestations are vine weevils, for example, can be tolerable, heavy ones cause a significant Pea leaf and pod spot controlled in gardens by beneficial Onion fly check to growth. Heavy infestations are nematodes. Pest species may feed characterized by the loss of much of the ■ Crops affected Pea. internally on their hosts, or are soil- ■ Crops affected Onion family: mostly green color in leaves before late summer. ■ Symptoms Sunken brown or yellow dwelling, attacking root hairs. They onion, but also leek, shallot, and garlic. ■ Control Effective treatments include spots appear on leaves, stems, f lower are sap-suckers and so may spread ■ Symptoms Young plants collapse in deltamethrin (on leek) or pyrethrum. stems, and pods. These lesions may virus diseases from plant to plant on early summer, with the roots eaten by also bear small, pinprick-sized, fungal their mouthparts. white maggots, up to 8mm (3⁄8in) long. Onion white rot fruiting bodies. ■ Control Parts of the garden from ■ Causes The maggots are the larval ■ Causes Various fungi, including which virus-infected plants have been stage of the f ly Delia antiqua, which ■ Crops affected Onion family. Ascochyta pisi and A. pinodes. They removed should not be replanted with resembles a house f ly. There is one ■ Symptoms The foliage turns yellow usually attack fully grown peas, but the same type of plant, otherwise they generation in early summer and a second and wilts. The base of the bulb and occasionally attack seedlings, usually may quickly become infected by the in late summer; the latter feeds on roots roots develop f luffy white fungal growth fatally. It persists from year to year on nematodes. The normal life cycle needs and burrows into the bulbs, causing (see p.250), which later produces tiny plant debris and, if seeds are collected soil moisture to develop, but dormant secondary rots to set in. black fruiting bodies (sclerotia). The from infected pods, the resultant larvae and eggs protected in cysts can ■ Control Grow onions from sets; they sclerotia fall off into the soil, where they seedlings will succumb, too. survive adverse soil conditions for many are less vulnerable than seedlings to can persist for seven years or more. ■ Control Clear up and burn infected years. attack by first-generation maggots. ■ Cause A fungus, Sclerotium cepivorum. plant material at the end of the season. Growing the plants under horticultural ■ Control Remove and burn infected Do not save seed from infected plants. Nematodes and their associated viruses f leece will keep out egg-laying females. plants as soon as seen and do not grow Sow fresh seed in a new site in spring. are most often spread in gardens on Lift infested plants and destroy them members of the onion family on the infected plant debris, or in soil on boots, before the maggots move into the soil same site for at least eight years. The Pea moth tools, and plant rootballs—maintain to pupate. There are no chemical onion cultivar ‘Norstar’ is known to good hygiene. There is no effective controls available to amateur gardeners, exhibit a degree of resistance. There ■ Crops affected Pea. chemical control available to gardeners and maggots inside the bulbs would be is no chemical treatment available. ■ Symptoms Caterpillars, to 1⁄4in (6mm) for nematodes. See also Potato cyst inaccessible anyway. long, with dark-dotted, creamy white nematode, Root knot nematode, Stem Parsnip canker bodies and black heads, feed within the and bulb nematode, Virus vectors. Onion nematode: see Stem and bulb pods on developing peas (see p.250). nematode. ■ Crops affected Parsnip. They occur in greatest numbers during Nitrogen deficiency ■ Symptoms Roughened cankers mid- to late summer. Onion neck rot appear on the root, especially at the ■ Cause Caterpillars of the pea moth, ■ Crops affected Various. shoulder. They are usually red-brown, Cydia nigricana. Eggs are laid when peas ■ Symptoms Growth is reduced and ■ Crops affected Onion family. orange-brown, or black. are in f lower; the adult moths are active leaves are small and yellowed (chlorotic). ■ Symptoms The bulb scales of infected ■ Causes The fungus Itersonilia between early and late summer. Early- In some plants, red or purple discoloration onions become semitransparent, pale pastinacae or, less commonly, or late-sown peas, which f lower outside of the leaves may occur as chlorophyll brown, and soft. The affected areas Mycocentospora acerina. It may spread this period, usually escape infestation. levels drop. The oldest, lower leaves are develop a dense gray fungal growth and to the soil from infected leaf spots and ■ Control Early and late sowings avoid affected first, but if the deficiency is not begin to dry out, taking on a mummified often enters through damaged root hairs. the egg-laying period. Spray other sowings corrected, all parts of the plant may be appearance. Black tiny fruiting bodies Carrot f ly damage (see p.250) is also a with deltamethrin or lambda-cyhalothrin affected. Flowering, fruiting, and root (sclerotia), which may be several significant point of entry. about a week after the onset of f lowering or tuber formation are impaired. millimeters long, arise on affected parts ■ Control No control is available. Grow to kill the hatching caterpillars. ■ Causes Most soils can develop and are often clustered around the neck resistant cultivars, such as ‘Avonresister’. nitrogen deficiency, but it is more end of the bulb. The rot is often first Improve soil drainage and avoid or Pea seed beetle: see Bean beetle. prevalent on light soils and those with noticed on stored bulbs. remove all potential sources of root a low organic matter content. Plots ■ Cause The fungus Botrytis allii. It is injury. Late sowing at closer than normal Pea thrips that have been heavily cropped are also the commonest cause of rot in stored spacings produces smaller roots, which susceptible. In cool springs, nitrogen onions. The sclerotia can persist in the appear to be less susceptible to canker. ■ Crops affected Pea and fava bean. deficiency may occur temporarily, but soil or on onion debris, as a source of ■ Symptoms Foliage and pods are this is usually self-righting as the soil reinfection. Pea and bean weevil distorted and discolored with a silvery warms up and soil bacteria become active. ■ Control Do not grow onions on the sheen or brownish scarring. Pea pods Soils that have been heavily mulched same site for more than three years in ■ Crops affected Pea and fava bean. contain only a few peas at the stalk end with wood chips may suffer deficiency succession. Buy seed and sets only from ■ Symptoms The margins of pea and of the pod. The adult thrips are black, because nitrogen is removed from the soil a reputable supplier, as the fungus may bean leaves have U-shaped notches at 1⁄12in (2mm) long, with narrow, as the lignin in the wood is broken down.

A–Z OF PLANT PROBLEMS 259 elongated bodies. The nymphs are damage caused by peach leaf curl (see this fungus thrives in exactly the damp result from a lack of a compatible similar, but pale yellow. facing page). On expanded leaves, the and humid conditions in which pineapple pollinator or frost damage (see p.255) ■ Causes The pea thrips, Kakothrips damage forms broad bands on either crops are grown. Remove infected at f lowering time. With all fruits, poor pisivorus. The adults emerge in late spring side of the midrib; by midsummer, the plants, along with the soil in the vicinity pollination may also be a result of a lack and early summer. Populations peak blisters have turned black. Less than 1⁄8in of the roots. There is no chemical control of pollinating insects, usually bees, either between mid- to late summer and are (3mm) across, these lesions should not available to gardeners. because there are none in the vicinity, especially troublesome in hot, dry summers. be confused with the larger ones caused See also Foot and root rots, Potato blight, or because cold, wet or windy weather ■ Control Look out for thrips activity as by apple and pear scab (see p.251). Red core. prevents them from f lying. the pods develop and, if necessary, spray ■ Causes A microscopic mite, Eriophyes ■ Control When planting fruit trees, with deltamethrin, pyrethrum, or pyri lives within the leaves. The blisters Pigeons: see Birds. check on their pollination requirements lambda-cyhalothrin. are the plant’s response to chemicals that and plant accordingly; choose self- are secreted by the mites as they feed. Plum fruit moth pollinating cultivars if available. Choose Peach leaf curl ■ Control Although the unsightly sheltered spots to avoid frost damage; this lesions give the appearance of ill health, ■ Crops affected Plum, damson, and will also be beneficial for bees. Plant ■ Crops affected Peach, nectarine, and the damage is largely cosmetic and does gage. plenty of other f lowering plant species almond. not seriously affect cropping. None of ■ Symptoms Brown-headed, pale pink to attract pollinating insects. Use any ■ Symptoms Leaves develop pale green the insecticides available to amateur caterpillars, to 1⁄2in (12mm) long, feed chemical sprays with care, selecting puckering and blistering that later turns gardeners gives control. On lightly inside ripening fruits around the stone, specific pesticides where possible; try to bright red or purple (see p.250); they are infested small trees, affected leaves can and the damaged area is filled with spray at dusk when bees have ceased affected when or soon after they unfurl be picked off. If done thoroughly, this brown frass (excrement). Damaged fruits f lying. in spring. A white powdery layer of will reduce populations in subsequent ripen early and may have one or more See also Potassium deficiency. spores develops on the leaf surfaces, and years. depressions at the surface, where the affected leaves fall prematurely. When larva has eaten its way out. Poorly formed fruits a second f lush of leaves appears later Pear midge ■ Cause Caterpillars of Grapholita in summer, they are usually healthy. In funebrana. There is usually only one ■ Crops affected Cucurbits. nectarine crops, the infection may spread ■ Crops affected Pear. generation a year, but there may be two ■ Symptoms Fruits are small, pitted, to the fruits, causing rough, slightly ■ Symptoms After apparently making if summers are long and hot. When fully and unusually dark green with bright raised patches; peach fruits are usually good initial growth, shortly after petal fed, the larvae leave the fruits to yellow patches; they are also hard and unaffected. fall, pear fruitlets begin to turn black at overwinter beneath f lakes of bark. inedible. ■ Cause The fungus Taphrina deformans. the eye end (opposite the stalk). Affected ■ Control Collect and destroy affected ■ Cause Cucumber mosaic virus (see Growth and cropping is usually only fruitlets become distorted and extensively fruits in midsummer before the larvae p.254). The virus has a wide host range seriously compromised if repeated blackened before falling prematurely in have left. Pheromone traps attract male and can be spread on the mouthparts of infections occur over several successive early summer. If infestation is severe, moths, reducing the mating success of aphids and other sap-sucking insects. years. The fungus overwinters as spores the entire crop may be lost. Inside the females and so the incidence of maggoty ■ Control Destroy infected plants; that lodge in bark cracks and crevices, fruitlets are small, pale orange-yellow plums. More importantly, pheromone there are no chemical controls available. or in bud scales. They are spread by maggots, 1⁄12in (2mm) long. The traps indicate when adults are active Reduce risks of infection by controlling wind and in water splash. infestation causes fruitlets to swell and likely to be laying eggs; timing aphids and clearing weeds, which may ■ Control Remove affected leaves as abnormally, and it is this that gives the of chemical treatments is critical in form alternative hosts. Do not handle soon as seen. Keep trees well fed and impression of rapid initial growth. destroying the larvae before they enter healthy plants after touching infected watered to promote healthy new growth. ■ Cause The larvae of a small gall the fruit. Use deltamethrin or lambda- material without washing hands Plants grown under glass are seldom midge, Contarinia pyrivora. As the fruitlets cyhalothrin in early summer. thoroughly first. Resistant cultivars affected as spore dispersal is limited by drop, the larvae enter the soil and pupate include zucchini ‘Defender’, ‘Supremo’, the protection of the glass. It is worth in silken cocoons. They emerge as adults Pod spot: of peas, see Pea leaf and pod and ‘Tarmino’; cucumbers ‘Bush providing outdoor, wall-grown fruits the following spring. This midge is one spot. Champion’, ‘Crispy Salad’, ‘Jazzer’, with the protection of open-sided, clear of two that commonly affect pears. The ‘Petita’, and ‘Pioneer’; and marrows plastic covers; to be effective, this needs other, the aptly named pear leaf-curling Plum leaf-curling aphid ‘Badger Cross’ and ‘Tiger Cross’. to be in place from midwinter to late midge does not cause serious damage. spring. If trees cannot be protected, spray ■ Control Early- or late-f lowering pears ■ Crops affected Plum, damson, and Potassium deficiency with a copper-based fungicide several often escape pear midge, so choose these gage. times between mid- to late winter, but cultivars if possible. On small trees, pick ■ Symptoms The leaves become tightly ■ Crops affected Various. ensure that spraying is complete before off and destroy affected fruitlets before curled and crumpled shortly after they ■ Symptoms The most frequent blossom burst. Repeat the spraying in fall the larvae finish feeding and certainly emerge in spring (see p.250). On the symptom is poor f lowering, often before leaf fall. before the fruitlets fall. Prevent the undersides of the leaves, small, pale with undersized f lowers and a adults laying eggs by spraying with yellow-green insects, up to 1⁄12in (2mm)) correspondingly poor fruit set. On Pear and apple canker: see Canker. deltamethrin or lambda-cyhalothrin long, are found, along with their tomato crops, this is often a factor in when blossom buds show color, but cast skins. blotchy ripening (see Tomato blotchy Pear and cherry slugworm before f lowers open. ■ Cause A sap-sucking aphid, ripening, p.263). Leaves may appear Brachycaudus helichrysi. During late spring scorched at the tip or margins, and ■ Crops affected Pear, plum, cherry, Pear scab: see Apple, pear, and olive and early summer, winged adults migrate show purple-brown spotting beneath. and almond. scabs. to their alternate hosts—a wide range of ■ Causes A deficiency of potassium ■ Symptoms Foliage is eaten by club- herbaceous plants. After this period, new in the soil. It is most common on light, shaped, pale yellow, caterpillarlike Phytophthora leaves grow normally. The aphids return sandy soils and those with a low clay larvae, up to 1⁄2in (1cm) long, between in fall to lay overwintering eggs at the content. late spring and mid-fall. They are ■ Crops affected Various, including base of twigs and buds. This generation ■ Control Apply rock potash or sulfate covered with black mucilage, giving pineapple, apple, and other tree fruits, hatches in late winter and infests the of potash in spring and fall. them a sluglike appearance. They feed raspberry, and strawberry. breaking buds. by grazing off the upper leaf surfaces, ■ Symptoms Plants begin rotting at the ■ Control Reduce overwintering eggs Potato black leg skeletonizing them and causing damaged collar between the roots and the stem by using a plant oil winter wash on dry, parts to become brown and desiccated. base. Foliage may be sparse, discolored, mild days between early and midwinter. ■ Crops affected Potato. ■ Cause The larvae of a sawf ly, Caliroa and show signs of dieback. Roots are Small trees may be sprayed with ■ Symptoms Leaves are stunted and cerasi, which produces two or three blackened and finer roots are killed. thiacloprid when the leaves emerge. yellowed with slightly incurled leaf generations during the summer. The Stems may show signs of dieback and the margins, most noticeably on the larvae overwinter in cocoons in the soil. whole plant may be killed. Bark under Poor fruit setting uppermost leaves. The stem base is ■ Control Contact insecticides offer the main stem or trunk is reddish- or blackened, slimy, and rotten at ground good control on trees small enough to blackish-brown. ■ Crops affected Many fruit crops: level. If the stem is cut across, it reveals spray. Spray when larvae are seen with ■ Causes Various soil- or water-borne raspberry, strawberry, apple, pear, and distinct, discolored, or black spotting. deltamethrin, pyrethrum, or lambda- fungi of the genus Phytophthora; other tree fruits. The parent tuber is completely rotted cyhalothrin. P. cinnamomi is common and can cause ■ Symptoms On tree fruits, f lowers and plants may die before a crop is root rot of tree fruits. P. cactorum causes appear as normal but fail to set fruit. produced. Pear leaf blister mite fruit rot of apples and collar rot of apples On raspberry and strawberry crops, some ■ Causes The bacterium Pectobacterium and other fruit trees; P. syringae also fruits form incompletely or are distorted. atrosepticum. It is most prevalent in ■ Crops affected Pear; apple crops are affects several tree fruits in a similar way. On raspberries, individual drupelets on wet soils and may be introduced on also affected, but less frequently. Phytophthora is also one of the causal the berry may be dried and brown, while symptomless, but nevertheless infected, ■ Symptoms Young pear leaves develop agents of damping off (see p.254). other adjacent berries are perfect. seed tubers. When these are planted, pink or yellowish-green blisters, or raised ■ Control Maintain good hygiene and ■ Causes There can be several causes. affected plants may be seen scattered blotches that superficially resemble the water only with mains water. Improve On fruit trees, poor pollination may throughout a crop of healthy, apparently drainage and ventilation. Unfortunately,

260 A–Z OF PLANT PROBLEMS unaffected plants. The bacterium to attack. The organism thrives in soils but now very uncommon, potato wart occur on the fruits, which may also infects via wounds made while plants that have been limed, and it is less disease. In powdery scab, the tuber become distorted. Affected shoot tips are in the soil, or when seed tubers common on acid soils. protuberances are smooth, not warty, may develop dieback. are lifted. ■ Control Do not lime the soil prior to and wart disease never affects the roots. ■ Cause The fungus Diplocarpon mespili, ■ Control Do not lift potato crops in planting potatoes. Improve the organic ■ Cause The fungus Spongospora which overwinters on infected shoots. wet weather, and lift carefully to avoid content of the soil and keep it well subterranea. It is most common in wet ■ Control Remove and burn fallen causing any damage; both factors make watered in dry weather; there is a link seasons and on heavy soils, especially leaves, and prune out infected stems. infection more likely. Clear away all between dry soil conditions and the on sites that have grown crops of Difenoconazole applications for powdery crop debris, and do not allow heaps of proliferation of this organism. Use acidic potatoes for many seasons. mildew may give incidental control. discarded potatoes to stand; they may materials, such as sulfate of ammonia or ■ Control Dispose of all infected tubers; form a source of infection. Store only superphosphate, to reduce scabbing. do not put them on the compost heap Rabbits perfectly healthy, undamaged potatoes; Although crops are seldom badly reduced because they will spread the disease. infected ones rot in store and the rot will and tubers remain edible, they usually Do not grow potatoes for at least three ■ Crops affected A wide range. spread to healthy tubers. Avoid growing have to be peeled deeply to become years following an outbreak. Improve ■ Symptoms Grazing occurs on all cultivars known to be susceptible: ‘Arran palatable. The following potato cultivars soil aeration before planting. ‘Desiree’, parts of leafy plants, to a height of about Pilot’, ‘Majestic’, ‘Maris Bard’, ‘Desirée’, show some resistance: ‘Arran Pilot’, ‘Hermes’, ‘King Edward’, ‘Pixie’, 20in (50cm). Tree bark may be gnawed, and ‘Estima’. ‘Golden Wonder’, and ‘King Edward’. and ‘Sante’ show some resistance to and if the damage girdles the stem or There is no chemical treatment available. powdery scab. trunk, the tree dies. Bark feeding Potato blight occurs at any time of year, but trees are Potato cyst nematode Potato viruses especially at risk when snow is on the ■ Crops affected Potato and tomato. ground and other food sources are scarce. ■ Symptoms Necrotic brown patches ■ Crops affected Potato and tomato. ■ Crops affected Potato. New plantings may also receive special appear on the leaves and fruits or tubers ■ Symptoms Leaves become ■ Symptoms Various, depending on the attention; like deer, rabbits are (see p.250), mainly at the tips and at the progressively more yellowed and dried potato variety, the growing conditions, inquisitive feeders. margins. As they enlarge, the leaf withers up from the base of the stem upward. and the virus or combination of viruses ■ Cause Rabbits, Oryctolagus cuniculus. and dies. Slightly f luffy, white fungal Potato plants die prematurely, usually by involved. Leaf symptoms include yellow ■ Control Trapping, shooting, and growth may appear around the spots, mid- to late summer, and so produce a f lecking, streaking or mosaicing, dark gassing are generally unsuitable usually beneath the leaves, in humid reduced crop of small potatoes. When spotting and leaf distortion, and techniques in a garden situation. The conditions or in wet weather. Haulms potato cyst nematode first appears in a stiffening and upward rolling of the only reliable way of excluding rabbits is of infected potatoes develop dark brown garden, small clumps of potatoes within leaf lets. If home-saved seed potatoes are to erect fencing. This must be 4–41⁄2ft patches and collapse. Skins of infected the rows show symptoms. Each time grown for many years in succession, (1.2–1.4m) tall, with 12in (30cm) of the tubers have sunken dark patches with potatoes are grown on the same site, the expect a gradual decline in vigor and netting buried below ground, angled red-brown coloration on the f lesh area of affected plants enlarges, until it crop quality due to a buildup of viruses. outward, to deter them from digging beneath. These are dry at first, but often finally becomes impossible to obtain a ■ Causes Several different viruses through or burrowing beneath. The become foul-smelling and slimy due to worthwhile crop. Tomatoes are also including potato leaf-rolling virus, mesh size must be a maximum of 1in secondary infections, which usually rot affected. If plants are carefully dug up, tobacco rattle, and potato viruses x (25mm), otherwise young rabbits can the entire tuber. spherical cysts, up to 1⁄16in (1mm) across, and Y. squeeze through. Do not forget to net ■ Cause The fungus Phytophthora can be seen on the roots. Each is the ■ Control None is available. Always gates as well, and keep them closed when infestans. The same organism causes blight body of a female nematode and may grow potatoes on a fresh site, do not not in use. Protect trees with individual on tomatoes. Spores produced by the leaf contain up to 600 eggs. save tubers for seed, and buy in certified, guards, either netting or spiral tree lesions are spread by rain splash and air ■ Causes There are two species of cyst virus-free seed potatoes. guards around the base of the trunks. currents, and they may wash down to the nematode that affect tomato and potato Animal repellent products are generally tubers in rainfall or irrigation water. The crops. Golden cyst nematode, Globodera Powdery mildew not reliable, but domestic cats can be fungus becomes active only when there rostochiensis, has cysts that are white at very efficient hunters of rabbits. are two consecutive 24-hour periods with first, passing through a yellow phase ■ Crops affected Various. a minimum temperature of 50ºF (10ºC) before turning brown at maturity. Cysts ■ Symptoms Powdery white fungal Raspberry beetle and a relative humidity of 89 percent or of white cyst nematode, G. pallida, turn growth occurs, first on upper leaf more for 11 hours in each of the 24-hour from white to brown without an surfaces, later often spreading to lower ■ Crops affected All cane fruits, periods. intermediate yellow stage. Both develop surfaces. Mildew may also affect all other including raspberry, blackberry, and ■ Control Reduce the risk of infection within the roots and when mature, the above-ground plant parts, but its location hybrid berries. spreading to the tubers by earthing females swell and burst out through the depends on the mildew and plant species ■ Symptoms Ripe fruits exhibit up deeply. If haulms show symptoms root wall. Poor growth is due to involved. Affected leaves and other parts desiccated patches at the stalk end of the of infection, remove them as soon as disrupted uptake of nutrients and water may yellow and become distorted; berries (see p.250). Creamy white grubs, they begin to die down. The genetic inf licted by the nematodes. distortion is particularly common when up to 3⁄8in (8mm) long, feed at the base of population of the fungus is ever- ■ Control There is no chemical control young growth is affected. Affected fruits the berries initially, then move into the changing. The resistance of old cultivars, available to amateur gardeners. Potato may split or crack because they cannot inner core or plug. They are most readily such as ‘Cara’, ‘Kondor’, ‘Orla’ ‘Markies’, cyst nematode eggs can remain encysted expand normally. On leaves, mildew may seen after picking, when they leave the and ‘Valor’, has been overcome by and viable in the soil for many years. The kill small areas of tissue, which will die fruit and crawl around the bowl. one dominant new strain. Spray the eggs are stimulated to hatch by chemicals and fall away, giving a shot-hole effect. ■ Cause The larvae of a small gray- foliage with a copper-based fungicide that are secreted into the soil by the host Growth may be poor and, in extreme brown beetle, Byturus tomentosus, which such as Bordeaux mixture or copper plants’ roots. Adopting a rotation system cases, dieback or even death may follow lays its eggs on the f lowers during early oxychloride. If weather conditions may delay the buildup of damaging pest premature leaf fall. and midsummer. are favorable for fungal growth, or a levels, but the normal three- or four-year ■ Causes Various fungi, including ■ Control Timing of controls is critical “Blight Infection Period” warning rotation is not sufficient to eliminate species of Erysiphe, Golovinomyces, in preventing newly hatched grubs. On is given on local radio or farming them. Once a serious nematode problem Neoerysiphe, and Podosphaera. These fungi raspberry crops, spray when the first programmes, spray as a precaution. has developed, the problem is intractable. are most prevalent where soils are dry, fruits turn pink; on blackberry crops but the air around the plants is humid when the f lowers first open; and on Potato common scab There are some potato cultivars with a and stagnant. loganberry and other hybrid berry crops, measure of resistance, such as the earlies ■ Control Keep plants adequately spray at 80 percent petal fall. Spray with ■ Crops affected Potato, rutabaga, ‘Accent’, ‘Nadine’, ‘Pentland Javelin’, watered but avoid overhead watering. deltamethrin at dusk to minimize the turnip, radish, and beets. ‘Rocket’, and ‘Swift’, and the maincrops Remove affected leaves promptly. Seek danger to any pollinating insects. ■ Symptoms The tuber develops rough, ‘Alhambra’, ‘Cara’, ‘Harmony’, out resistant cultivars. Some crops may raised, corky patches on the skin (see ‘Kingston’, ‘Maris Piper’, ‘Maxine’, be sprayed with a suitable fungicide, for Raspberry cane blight p.250). The skin ruptures leaving the ‘Sante’, and ‘Stemster’. example difenoconazole, myclobutanil scabs with ragged edges. Damage may or triticonazole. ■ Crops affected Raspberry. be superficial or may result in cracking Potato powdery scab ■ Symptoms Areas of bark peel away or pitting. The f lesh is usually Premature seeding: see Bolting. from the canes in summer and fall and undamaged, although there may be ■ Crops affected Potato and tomato. the stems die back, becoming very some discoloration beneath the scabs. ■ Symptoms Small, scabby patches Quince leaf blight brittle. Minute, black, fungal fruiting ■ Causes Streptomyces scabies, an develop on potato tubers. They are bodies form on dead stems and eject organism that is related to both fungi almost circular with a slightly raised ■ Crops affected Quince. spores. and bacteria. It is particularly common margin. When the scabs mature, they ■ Symptoms Many small, irregular red ■ Causes This is a fungal infection, on sandy soils that are deficient in burst open to release spores into the soil. spots appear on the leaves; the spots later caused by Leptosphaeria coniothyrium organic matter, but it occurs naturally There may be cystlike growths on roots turn turn black and may join together. which enters wounds in the canes. The as part of the microf lora in most soils. and stolons. In rare instances, a canker The leaves turn yellow before falling wounds can result from pruning, late Potatoes planted in plots that were form of powdery scab develops causing prematurely. Sometimes, similar spots spring frosts, or the cane midge larvae, formerly grassland are especially prone marked deformations of the tuber, which resemble symptoms of the notifiable,

A–Z OF PLANT PROBLEMS 261 Resseliella theobaldii, feeding beneath the ■ Causes Various viruses. The most pesticides. Biological control with the secrete a protective, waxy white powder bark. The larvae are small, red, or pink common are raspberry mosaic, curly predatory mite Phytoseiulus persimilis gives or f luff and this will be seen on soil and 1⁄6in (4mm) long. dwarf, and raspberry yellow dwarf; they good results if introduced before heavy particles around the site of infestation. ■ Control Prune carefully to avoid may occur alone or in combination. infestations develop. It needs warm ■ Causes Several species occur in creating ragged cuts and protect from ■ Control Remove and dispose of daytime conditions in the absence of gardens and they are frequently host- frost where possible. If cane midge affected plants promptly. Choose a pesticides to become established. It specific: Smynthurodes betae on French is present, cultivate the soil around new site for replacement canes, and can also be used on outdoor plants and runner bean crops, Trama troglodytes the bases of the canes in winter to expose do not use the same site again for in summer. Misting indoor plants on Jerusalem artichoke, Dysaphis crataegi overwintering larvae to bird predators raspberries. Control insect vectors, with water twice daily provides high on carrot and parsnip, and Pemphigus and bad weather; spray canes with such as aphids; some viruses are also humidity, which will suppress mite bursarius on lettuce. deltamethrin in late spring and repeat spread by soil-dwelling nematodes. activity. Alternatively, use sprays as ■ Control Root aphids are more two weeks later. If blight does occur, for fruit tree red spider mite; several difficult to control than leaf feeders. cut out affected canes and any discolored Red core applications will be necessary. Crop rotation helps avoid infestation wood from the crown. Spray plant by aphids that have overwintered in crowns and any new growth with ■ Crops affected Strawberry. Replant diseases the soil on the remains of last year’s copper oxychloride. ■ Symptoms Clumps of stunted plants, crop. Insecticides do not give good with stiff, red-brown leaves, are noticed ■ Crops affected Soft fruits, tree fruits. control fo root aphids. Raspberry cane spot: see Cane spot. in late spring. Roots are discolored with ■ Symptoms Newly planted trees and See also Lettuce root aphid. a red inner core. bushes fail to thrive and may show signs Raspberry leaf and ■ Cause The fungus Phytophthora of dieback. There are no obvious cultural Root knot nematodes bud mite fragariae. It proliferates in wet, heavy problems, such as drought, waterlogging, soils and produces resistant spore stages or poor planting technique. This occurs ■ Crops affected A wide range. ■ Crops affected Raspberry. from the deteriorating roots. These where new trees are planted on a site ■ Symptoms Plants fail to thrive, ■ Symptoms Rounded, pale yellow are released into the soil and may persist previously occupied by the same species. display poor foliage color, and knobby blotches appear on upper leaf surfaces for more than 10 years. The fungus is ■ Causes The exact mechanism of swellings form on the roots. from late spring onward, with slightly easily introduced on boots and tools, replant problems is unclear, but it may ■ Causes Microscopic nematodes that darker, corresponding patches beneath. or contaminated plants. involve nematodes, viruses, soil-borne live within the roots and cause knobby By midsummer, the leaves may be ■ Control None is available. Remove fungi, and nutritional depletion. The last swellings (not to be confused with extensively discolored and those at the and burn infected plants promptly, may be a result of infection of roots that nitrogen-fixing nodules normally found shoot tips may be distorted. Fortunately, together with the soil from the root renders them incapable of taking up on the roots of legumes).The tissue damage is largely cosmetic. Affected vicinity. Do not grow strawberries on nutrients properly. There is also evidence distortion they cause disrupts the intake canes grow to their normal height and the same site again and avoid moving that some plants’ roots exude chemicals of water and nutrients. There are several usually produce an adequate crop. The soil from the infected site elsewhere to deter growth of plants of the same species, most in the genus Meloidogyne. symptoms can be mistaken for viral in the garden. species too near to them; a mechanism ■ Control Remove affected plants along infection, but with viruses, the crop that, under natural circumstances, would with the soil around their roots. There and vigor are both adversely affected. Red spider mites prevent competition. is no effective chemical control available ■ Cause Microscopic mites, Phyllocoptes ■ Control Affected plants may recover to gardeners. gracilis, suck sap from the leaf undersides. ■ Crops affected Many, including tree if moved to a fresh site. The problem is In fall, they hide in or near buds, but fruits and greenhouse crops. best avoided by not planting on a site Root rots: see Foot and root rots. cause no damage in winter. ■ Symptoms Foliage loses its healthy where the same species has been grown ■ Control Cultivars vary in their green color and develops a silvery sheen, previously. There is no reliable control. Rosy apple aphid susceptibility: ‘Malling Jewel’ is often becoming increasingly dull and chlorotic. If absolutely necessary, the soil may be attacked, while ‘Malling Promise’ shows On fruit trees, a fine pale mottling may removed and replaced with virgin soil. ■ Crops affected Apple. some resistance. Plants grown in warm, be seen on the upper leaf surfaces (see A “cube” of soil, that has a minimum ■ Symptoms Young foliage is infested sheltered spots are more likely to suffer p.250). Large numbers of tiny, dark dimension of approximately 18 x 18 x in spring by pinkish-gray insects, up to heavy infestations. No chemical control red mites, 1⁄16in (1mm) long, and their 18in (45 x 45 x 45cm), must be replaced, 1⁄12in (2mm) long. Their feeding causes is available. spherical eggs can be seen beneath so this is not a task to be undertaken curling of the leaf tips and yellowing the leaves. Severe infestations cause lightly if many plants are to be replaced. of the leaves. They may also feed on Raspberry spur blight premature leaf fall. Under glass, plant Planting well-established, container- fruitlets, which may fail to grow and leaves exhibit similar dullness and loss grown plants with a good root system, have a pinched appearance at the eye ■ Crops affected Raspberry, loganberry, of color. Close examination of the lower feeding with a high-nitrogen fertilizer, end (opposite stalk). Not all fruits will blackberry, and hybrid berry crops. leaf surface, preferably with a x10 hand and watering well can help minimize be affected, and some will continue to ■ Symptoms Buds of new canes develop lens, will reveal spherical eggs and tiny, the problem. It is essential also to keep develop normally. dark pink-purple patches around them, yellow-green mites with two large dark the soil in good health by incorporating ■ Cause The rosy apple aphid, Dyaphis which enlarge and spread down the marks on the back near the head end plenty of well-rotted organic matter. plantaginea. It overwinters on the tree canes causing widespread discoloration. (sometimes known as two-spotted mites). as eggs, which hatch at bud burst; the In fall, canes develop a grayish silver In fall and winter, they turn orange- Reversion disease aphids are active on the tree until early color and are covered in many pinprick- red. In heavy infestations, silky white or midsummer. They then migrate to sized, black fruiting bodies. Infected webbing covers the leaves and stems. ■ Crops affected Black currant. their summer wildf lower host, plantains. canes bear very few viable buds in the Leaves dry up and fall prematurely, and ■ Symptoms Leaves are produced that ■ Control Control the overwintering following spring and, if they survive, only young leaves remain at the stem tips. are slightly yellow, with unusually small eggs with a plant oil wash in winter or produce very few fruits. ■ Causes There are two common main veins. Leaves are small with fewer spray at bud burst with deltamethrin, ■ Cause The fungus Didymella applanata. species of red spider mite. The sap- lobes than normal. Flowering and lambda-cyhalothrin, or thiacloprid. It occurs in most seasons but is especially feeding fruit tree red spider mite, cropping are reduced. prevalent in wet weather. Panonychus ulmi, occurs outdoors. The ■ Causes A graft-transmissible virus Rusts ■ Control Avoid high-nitrogen heaviest infestations occur in hot, dry that is most usually spread by big bud fertilizers, which induce soft, more summers. Under glass, the glasshouse mite (see p.252). Big buds are also often ■ Crops affected Various. disease-prone growth. Avoid red spider mite, Tetranychus urticae, is the present. ■ Symptoms Foliage and stems may overcrowding, which encourages culprit. In hot, dry summers, it moves ■ Control Remove infected plants be affected, depending on the host plant rapid spread, by selecting only the outdoors to attack a wide range of crops. promptly; the disease is untreatable and and the rust involved. Spore masses strongest canes when pruning. Prune ■ Control The fruit tree red spider mite plants become infectious, spreading the or pustules are usually bright orange or out affected canes. No fungicides is not generally a problem on unsprayed disease to healthy plants nearby. Always dark brown, but their color may vary are sold to gardeners for this problem, trees since predatory mites and other buy plants that are certified as virus-free. at different times of the year and they but copper oxychloride applications predators provide a degree of natural frequently begin yellow or orange and for cane spot (see p.253) may give control. Sprays are often indiscriminate Root aphids turn brown later. They often have several incidental control. and kill many beneficial insects. Where distinct spore stages, commonly known trees have been routinely sprayed, mite ■ Crops affected Various, including as winter, spring, and summer spores. Raspberry viruses populations build to problem proportions cardoon, Chinese artichoke, Jerusalem Affected areas usually discolor and may and their overwintering eggs, laid in artichoke, artichoke, French bean, wither and die. ■ Crops affected Raspberry. bark crevices, may be so numerous as runner bean, lettuce, carrot, and parsnip. ■ Causes Various fungi, the most ■ Symptoms Leaves develop yellow to give the bark a distinct red hue. If ■ Symptoms Infested plants show poor common of which are species of Puccinia patterning, usually in mosaic form, red spider mite becomes a problem, growth and wilt readily in warm weather, (see p.250), Uromyces, Phragmidium, and this is accompanied by various spray with fatty acids, or plant oils. even when the soil is moist. Dirty-cream Melampsora, and Gymnosporangium. Some distortions, down-curling of the leaves, aphids, sometimes blue-green, up to 1⁄16– need an alternate host to complete their stunting, and general failure to thrive. Glasshouse red spider mites breed 1⁄8in (2–3mm) long, are seen on the roots life cycle, while others are monospecific. Cropping is often reduced. rapidly in warm conditions and strains and on stem bases. Root aphids often All need a moist environment to become have developed that are resistant to

262 A–Z OF PLANT PROBLEMS infectious, so they are generally more or from drifting spray, may also produce sources of infection, such as fallen Snails troublesome in damp weather conditions. similar symptoms, as can the use of timber, and remove and burn them. ■ Control Remove affected leaves. inappropriate pesticides. Some plants are ■ Crops affected Various. Improve air circulation, and where very sensitive to certain chemical sprays. Plum and cherry crops are especially ■ Symptoms A wide range of plants are possible, choose resistant cultivars. ■ Control Water in the early evening prone to infection and ‘Victoria’ plums damaged between spring and fall; soft Currant and gooseberry crops may be so that leaves have chance to dry off are the most susceptible. The rootstock parts are most susceptible. Flowers, sprayed with copper-based fungicides. before nightfall and are not exposed also inf luences susceptibility, with leaves, fruits, and stems are eaten, with and difenoconazole can be used to control to bright sunlight immediately afterward. ‘Brompton’ being very vulnerable. Other irregular holes rasped away. Often their rusts on certain fruit and vegetables. In greenhouses, provide adequate cultivars, such as ‘Pixie’, have a marked surfaces are grazed off and the tissue See also Leek rust, Mint rust. shading. Check label recommendations degree of resistance. beneath becomes desiccated and browned for pesticides to ensure that they are or bleached. This is apparent on the Scale insects suitable for use on the plant in question. Slugs stems of cardoons. Silvery slime trails are left behind. Snails are most active after ■ Crops affected Various. Shanking of grapes ■ Crops affected Various. dark and in wet weather. They are less ■ Symptoms The stems and foliage of ■ Symptoms A wide range of plants are common on acid soils, which lack the many garden and greenhouse plants can ■ Crops affected Grape vines under damaged by slugs; soft parts of plants calcium necessary to form their shells. be affected. The insects secrete a waxy cover. are most susceptible. Irregular holes are ■ Causes The most common pest is shell or scale over their bodies. They are ■ Symptoms Individual berries in a eaten in f lowers, leaves, and stems. Some the garden snail, Cornu aspersum. Banded mobile when young, but once they have truss fail to color up normally. Black slugs are soil-dwelling and eat tubers Cepaea species are much less damaging. found a suitable niche, they settle down grapes remain red and white (green) of potatoes (see p.250) and Jerusalem ■ Control As for slugs. Biological and are fixed in place for the rest of their grapes become translucent. The berries artichokes. Slugs secrete a slimy, silvery control is less effective because snails lives. The scales may be gray or brown wrinkle and begin to resemble raisins, mucilage from their bodies; these silvery live mainly above the soil and are less in color, and f lat or domed in shape. The and they develop a watery or unpleasant deposits, left as trails on affected plants, likely to be infected by bacteria-carrying size, which varies according to species, f lavor. are a key sign of slug and snail damage. nematodes. Since snails often hibernate is 1⁄16–1⁄4in (1–6mm). Some scale insects ■ Causes Cultural problems, including ■ Causes Several species of slugs occur communally, significant numbers can excrete honeydew, which hosts black under- or overwatering, underfeeding, in gardens: the gray field slug (Deroceras be trapped by strategic placement of sooty molds. Most outdoor species hatch overcropping, and stagnant soil reticulatum), the large black slug (Arion hibernation shelters such as old drainage in midsummer, but under glass, breeding conditions. ater), the garden slug (A. hortensis), and pipes, planks of wood, or upturned may occur through the year. ■ Control Cut out affected berries keeled slugs (Milax species). They are f lowerpots. Collect congregating snails ■ Causes Scale insects, many species. and spray the foliage with a foliar feed. ubiquitous and present through the en masse during the winter months and ■ Control Most scale insects conceal Make sure that drainage around the year, continuing to feed whenever dispose of them. their eggs beneath their own bodies. roots is unimpeded and water carefully temperatures remain above 40ºF (5ºC). Newly hatched nymphs are more and thoroughly, but not excessively. Most are night feeders. Split stone: see Splitting. vulnerable to insecticides, like fatty ■ Control Slugs can never be completely acids or plant oils. Silver leaf eliminated from gardens, so control Splitting See also Brown scale. measures should be concentrated on ■ Crops affected Stone fruits, protecting vulnerable plants, especially ■ Crops affected Various. Sclerotinia particularly plum and cherry, and also seedlings and soft-leaved plants, such as ■ Symptoms Fruits or stems split, peach, nectarine, almond, apple, and lettuce. Non-chemical means of control usually longitudinally, sometimes only ■ Crops affected Various. pear. include hunting by torchlight on mild, around the fruit stalk, while the rest ■ Symptoms Fruit and stem base ■ Symptoms Single or several branches damp nights. Slug traps consisting of of the plant appears perfectly healthy. infections are the most common, but develop leaves with a silvery sheen. If a jar half-filled with beer sunk into Earwigs may enter at the wounds. Cracks the majority of above-ground tissues affected stems of 1in (2.5cm) diameter or the ground invite slugs to death by may dry and heal over, but dieback and can be affected, becoming brown and greater are cut across, the inner tissues drowning. Grapefruit skins, placed open rotting may follow due to secondary slimy as they rot (see p.250). Large reveal central brown staining. Other end down, are also attractive traps; the infections entering the wounds. Fruits quantities of f luffy, cottonlike fungal apparently normal limbs may show victims can be collected and disposed of may have an impaired f lavor. growth develops, which is scattered with symptoms at a later date. Affected limbs in the morning. Plants in containers may ■ Causes An erratic supply of water black fruiting bodies (sclerotia). Fruits may die off and fall, or fail to leaf up the be protected by applying copper tape and nutrients, such as calcium deficiency, and tubers may be affected when in store. following spring. Fruiting bodies, often around the pots just below the rims. are the most common causes, along with ■ Cause The fungus Sclerotinia clustered together and adhering closely to poor pollination and great f luctuations sclerotiorum. It is most prevalent in cool, the bark, may form on dead wood. Their The parasitic nematode Phasmarhabditis in temperature, as in frost crack. damp conditions and overwinters in the exposed surface is dark purple-gray. hermaphrodita is used as a biological ■ Control Mulch to conserve soil soil. It then produces cup-shaped fungal These symptoms may be mimicked by control that can be applied where soils moisture and keep plants well fed and growths known as apothecia, which other causes, such as bad weather damage, are moist but well-drained, and above watered. Hand pollinate fruit crops. contain the spores that are responsible drought, malnutrition, or insect attack. a temperature of 40ºF (5ºC). It is most Observe damaged areas for signs of for the following season’s infections. ■ Cause The fungus Chondrostereum effective in spring and fall. The secondary infections and treat as ■ Control Remove and burn all affected purpureum. This is a fresh-wound parasite microscopic nematodes penetrate the appropriate. Remove damaged fruits— plants promptly. At the end of each of deciduous trees and shrubs, and slugs’ bodies when they enter the soil to they will rot and form a source of further season, dispose of all plant debris. Do pruning cuts or pest attack are the most seek shelter during the day and release infection. not grow susceptible plants on the same frequent wounding agents. Spores are a bacterium that causes a fatal disease site for at least four years following an produced from fruiting bodies on limbs in infected slugs. It is extremely useful Spur blight: see Raspberry spur blight. outbreak of the disease. of infected trees or on fallen timber. for controlling soil-dwelling slugs that It is spread on air currents, in water damage potato tubers. Under suitable Squirrels Scorch splash, and on pruning tools. The fungus conditions, it gives effective reduction produces a toxin that causes the upper in numbers for up to six weeks. ■ Crops affected Hazelnut, filbert, tree ■ Crops affected Various, but leaf surface to become detached from the and bush fruits, strawberry, and corn. greenhouse plant crops, such as grape main leaf blade, and air that accumulates Damage to tubers is also reduced if ■ Symptoms Squirrels eat shoot tips, vines, are usually more susceptible. between the two layers def lects light, crops are lifted as soon as they have f lower buds, nuts, and tree and soft fruits, ■ Symptoms Scorched tissue, usually giving a silvered appearance to the leaf. matured. Some potato cultivars are less and they are generally very destructive. of softer parts like petals or leaves, turns The infection is not carried by the susceptible than others to slug damage: They will even remove plant labels and pale brown or bleached. Damaged areas leaves themselves. ‘Pentland Ivory’, ‘Pentland Dell’, ‘Wilja’, use them to sharpen their teeth. dry out and become crispy. Stems are ■ Control None is available. Mildly ‘Stemster’, ‘Charlotte’, and ‘Estima’ ■ Cause The gray squirrel, Sciurus occasionally scorched, with the area of affected trees sometimes recover have some resistance. The following are carolinensis. damage appearing on the exposed side. spontaneously. In general, however, the especially vulnerable to attack: ‘Maris ■ Control Shooting, traps, and poisoned ■ Causes Hot or bright sun is the most infection spreads through the tree unless Piper’, ‘Maris Bard’, ‘Cara’, ‘Golden baits are used in forestry or large public common cause, but cold, dry winds can affected branches are removed. Cut them Wonder’, and ‘Kondor’. gardens, but these methods are also be very damaging. With sun scorch, off at least 6in (15cm) beyond the point impractical and undesirable in domestic the problem is exacerbated by droplets where staining is apparent, cutting back Poisoned baits in the form of slug gardens. Squirrels are very mobile, and of moisture on the leaf surfaces, which to clean white wood. Infection is least pellets can harm cats, dogs, and birds, others will quickly move into a territory magnify the sun’s rays. Sun scorch of likely to occur during the summer which may consume poisoned slugs, so to replace any that have been removed. bark is most likely on young, thin-barked months, so all pruning of susceptible use with great care. Scatter them thinly Use netting to protect fruits during trees. Water droplets may also increase trees should be undertaken in summer. among vulnerable plants according to the periods that squirrels are taking an low temperature damage if they remain Although it is no longer generally manufacturer’s instructions, to reduce interest in them. Permanent wire-mesh on the leaf surfaces during cold nights, recommended to use wound paints, it is risks to pets and wildlife. Slug pellets fruit cages are best; squirrels will chew especially in spring and fall. Accidental certainly recommended in trees that are containing metaldehyde cause slugs to through plastic. contact with weedkillers, either directly susceptible to silver leaf and should be secrete an excess of slime and they die done straight after pruning. Locate any of dehydration, but slugs may recover in wet conditions. Ferric phosphate pellets are less toxic to pets and wildlife. Smut: see Corn smut.

A–Z OF PLANT PROBLEMS 263 Stem and bulb nematode unlike most sap-sucking pests, they feed its eggs on the roots of turnips, rutabagas, is a pathogenic nematode, Steinernema readily on upper leaf surfaces instead and leafy brassicas. The growth of leafy kraussei. Water the nematodes into the ■ Crops affected Onion family. of concealing themselves beneath. brassicas is seldom impeded, but the pest potting mix in late summer, while it ■ Symptoms Young onion plants are ■ Causes Most thrips are narrow- is more troublesome if it develops on the is warm and moist, but before the abnormally swollen and distorted.The bodied black insects, up to 1⁄12in (2mm) edible roots of turnips and rutabagas. grubs are large enough to cause serious tissues become soft and mealy, and they long, with two pairs of heavily fringed ■ Control There are no effective damage. Pathogenic nematodes are are readily infected with secondary rots. wings. The wings are folded when not chemical controls available to amateur ineffective in dry, heavy, or cold soils Plants usually die before reaching in f light so the hairy fringing may gardeners. (less than 41ºF/5ºC). There are no maturity; onions may produce bulbs if not be apparent. Immature nymphs suitable insecticides available for use infested late in the season, but they will are wingless and creamy yellow. Some Two-spotted mite: see Red spider mite. on edible plants. rot in store. thrips are virus vectors. The most ■ Causes The microscopic nematode, common type on vegetable crops is Verticillium wilt Violet root rot Ditylenchus dipsaci. the onion thrips, Thrips tabaci, and on ■ Control There is no effective chemical peas, Kakothrips pisivorus. ■ Crops affected Many, including ■ Crops affected Asparagus, celery, control available to gardeners. Remove ■ Control As for pea thrips (see p.258) eggplant, olive, strawberry, apple, pear, and other leafy vegetables, carrot, potato, infested plants as soon as seen. Nematodes and onion thrips (see p.258). plum, cherry, and quince. beets, and parsnip. are spread in gardens on infested plant ■ Symptoms Plant foliage wilts. All ■ Symptoms Plants are yellowed and debris, or in soil on boots, tools, and Tip burn or nearly all of the leaves on affected stunted, but the most characteristic plant rootballs, so maintain good hygiene. branches or stems show symptoms, but symptom is seen on affected roots, Buy onion seeds and sets from reputable ■ Crops affected Chicory, lettuce. the whole plant is seldom affected tubers, and rhizomes. Their surfaces suppliers to reduce the risk of bringing ■ Symptoms Leaf margins are scorched simultaneously. Leaves may turn yellow are covered in dark purple fungal nematodes into the garden. Crop rotation and brown. or brown between the veins and then strands, and this felty mass often has may reduce infestations; grow crops that ■ Causes Calcium deficiency, botrytis, die. Stem death follows shortly after, considerable quantities of soil adhering are not affected, such as lettuce, rutabaga, or bacterial infection. Of these calcium but it may take several years for large to it. These closely packed threads bear turnip, and any of the brassicas. deficiency is the most usual cause. woody plants to succumb totally. large, velvety black fruiting bodies ■ Control As for calcium deficiency Smaller bushes or herbaceous plants, (sclerotia), which fall off into the soil Strawberry seed beetle (see p.253) and botrytis (see p.252). such as strawberries, may be killed where they persist. The tissue beneath within a single season. the fungal mycelium may turn brown ■ Crops affected Strawberry. Tomato blotchy ripening and rot; this, in turn, may play host to ■ Symptoms Seeds are taken from If the bark is removed from an affected secondary bacterial rots. the surface of ripening strawberries, ■ Crops affected Tomato. stem, staining can be seen on the ■ Cause The fungus Helicobasidium leaving small, desiccated brown patches. ■ Symptoms Randomly scattered vascular tissues beneath; purple-brown brebissonii (syn. H. purpureum).This is The fruits are sometimes eaten into patches of hard, green or yellow f lesh or brown streaks run the length of the most prevalent in wet, acid soils, in and this often looks like slug damage. remain unripened. Damage is visible stem but are more apparent at the stem warm conditions. The velvety black ■ Causes Fast-moving black carabid only on mature fruits, and those on the base. Roots also develop a central core sclerotia persist in the soil for many or ground beetles, 5⁄8in (15mm) long; lower trusses are the most often affected. of discolored tissue. years. they are Pterostichus species or Harpalus ■ Causes The disorder is usually ■ Causes The fungi Verticillium albo- ■ Control No effective chemical rufipes, both of which are active at night. associated with some form of atrum and V. dahliae. Both are common treatments are available. Lift and burn ■ Control Keep the strawberry bed malnutrition. A deficiency of potassium in plant debris, plant tissues, and soil; affected plants, if possible, before sclerotia clear of weeds to discourage a buildup (see p.259) is the most frequent cause, the latter species forms fungal resting are shed. Likewise, dispose of any of seed beetles (at other times of year, but dry soil or potting compost, or a bodies that persist in the soil. They remaining crop plants at the end of the they feed on weed seeds). You can use poorly functioning root system, may have a wide host range and many garden season. Improve soil drainage. Do not pit-fall traps (a jam jar sunk into the also play a part. High greenhouse weeds can harbor the infections. grow susceptible plants on the soil again. soil), but these may also trap beneficial temperatures will exacerbate the damage. ■ Control None available. Remove predatory beetles. Chemical controls ■ Control Keep plants well fed. In affected plants promptly, along with Virus vectors are not desirable because the fruits are particular, ensure that a high-potash the soil in the immediate vicinity of the thin-skinned, and chemicals used so feed (see p.20) is used. Keep the roots. The infection may be spread on ■ Many viruses that affect plants are near to harvest may persist. If absolutely greenhouse well ventilated and pruning tools, so always clean them spread by certain pests, and these necessary, treat plants with unripe fruits the plants well watered. thoroughly when they have been used on are described as virus vectors. Nearly with deltamethrin at dusk. an infected plant. Do not introduce the all of these are sap-feeders and have Tomato ghost spot same species of plant on sites that have piercing mouthparts; aphids (see p.251) Strawberry viruses previously supported infected plants. and thrips (see above) are common ■ Crops affected Tomato. examples. When they insert their ■ Crops affected Strawberry. ■ Symptoms Unripe fruits display rings Vine weevil mouthparts into virus-infected plants, ■ Symptoms Stunting and distortion of of pale green or yellow discoloration. they pick up some virus particles and the whole plant, with the same symptoms As the fruits ripen, the rings turn yellow ■ Crops affected Mainly strawberry. transfer them to new host plants when accompanying yellowing in the leaves. or pale orange. ■ Symptoms Both adults and larvae next they feed. Some soil-dwelling Various patterns of discoloration are ■ Cause The fungus Botrytis cinerea. cause damage. Adults eat irregular nematodes (see p.255) also transmit seen: streak, ring-spot, and mosaic or The fruit are edible; the discoloration notches from the leaf margins between viruses as they feed on plant roots. yellowing of leaf margins. Plants fail to is a hypersensitive reaction to fungal spring and fall, and although this This is one of the reasons why it is thrive and may not f lower or fruit well. spores. Spores are spread by rain or damage is largely cosmetic, it should so important to control pests; some ■ Causes Various viruses, the most water splash and on air currents, and alert the gardener to the far greater virus vectors feed on a wide range of common being strawberry yellow edge the fungus is widespread. potential damage caused by the fat, plants and are capable of transmitting or little leaf virus, arabis mosaic, ■ Control As the fruits remain edible, creamy white larvae under the soil. more than 100 viruses. Although they strawberry ring spot, and tomato black and rarely deteriorate further, there is Plants make slow growth, followed may not cause debilitating damage ring, which is spread by nematodes. no need to treat or remove them. Good by wilting and eventual death. The in themselves, the viruses that they ■ Control None available. Remove hygiene helps to eliminate sources of larvae (see p.250) eat plant roots and spread often do. Moreover, there are and burn affected plants as soon as infection. See also Botrytis. may sever them completely; they also no chemical treatments currently symptoms are seen. Control aphids remove the outer bark from woody available to control viruses. It is best (see p.251), which are important virus Turnip gall weevil stem bases. Plants grown in containers to destroy virused plants by burning, vectors. Do not grow strawberries on are particularly at risk of attack by and new plants of the same type should the site again. Do not propagate from ■ Crops affected Brassicas, including the grubs. not be grown on the soil that has infected plants; runners carry infection rutabaga and turnip. ■ Causes The adults and larvae of harbored them. without always showing symptoms. ■ Symptoms Plant roots produce the vine weevil, Otiorhynchus sulcatus. Always buy certified stocks of strawberry rounded swellings that enclose legless The adults are active at night between Viruses plants; they are guaranteed to be virus- white grubs, up to 1⁄6in (4mm) long. spring and fall. They are slow-moving, free when purchased. Symptoms are similar to those caused dull black weevils, to 1⁄2in (1cm) long, ■ Crops affected A wide range. by clubroot (see p.254). They are with pear-shaped bodies and and ■ Symptoms The most common Thrips distinguished by cutting galls open; antennae that are bent at an angle about effects of viruses are stunting and turnip weevil galls are hollow and may halfway along their length. They are distortion. Distortions may take the ■ Crops affected Many, including contain grubs, or have circular exit capable of laying many hundreds of form of crinkling, crumpling, curling, onion, leek, and pea. holes in them where the grubs have eggs over a period of several months. or rolling. Leaves and other above- ■ Symptoms A fine, silvery white left to pupate in the soil. Clubroot galls The legless, soil-dwelling larvae are ground parts of plants show various discoloration appears on upper leaf are solid and less regularly rounded. up to 1⁄2in (1cm) long, with slightly markings, usually yellow, and they take surfaces. Plant growth is checked. Adult ■ Cause Larvae of the beetle curved bodies. the form of spotting, mottling, mosaic, thrips may be visible on the leaves; Ceutorhynchus pleurostigma. The adult lays ■ Control Adult vine weevils can be streaking, or f lecking. Virused plants seen by torchlight at night and disposed of. The biological control for the grubs

264 A–Z OF PLANT PROBLEMS generally crop poorly, if at all, and they ones, such as apples and pears, wasps Pesticide resistance is a problem with lines along their bodies. The caterpillars, often suffer premature death. Some usually enlarge existing damage caused glasshouse whitef ly; biological control up to 1in (25mm) long, eat foliage viruses can infect without causing by bird pecks. with a tiny parasitic wasp, Encarsia between bud burst and late spring. visible symptoms and this is known as ■ Causes Various species of social formosa, is often the best remedy under They also eat fruit blossoms and make latent infection. It is often the case that wasp are significant fruit pests: Vespula glass. It must be introduced between holes in apple fruitlets, which become alternative hosts show no symptoms; germanica and V. vulgaris, and tree- mid-spring and late summer, when misshapen as they develop. cucumber mosaic virus (see p.254) for nesting species Dolichovespula media temperatures will be high enough for it. ■ Causes The larvae of the winter example, may exist in a number of and D. sylvestris. Release the wasp when pest populations moth, Operophtera brumata. Adult common weeds that act as a source ■ Control Protect ripening fruits by are still low; it needs time to breed moths emerge between late fall and of infection for other plants, even enclosing selected fruit trusses inside before it can control whitef ly. Sticky midwinter. Only males are winged; though these plants appear to be muslin bags or old nylon tights. If yellow traps are effective and useful the females have swollen bodies and perfectly healthy. wasp nests can be located, they can indicators of rising whitef ly populations. tiny wings incapable of f light. When ■ Causes There are many virus species, be controlled by using a phenothrin Sooty molds can be wiped off tomato the females emerge from pupae in the the majority of which are sole agents of and tetramethrin aerosol spray, or by and cucumber fruits with a damp cloth. soil, they crawl up tree trunks to lay disease. Some, however, infect plants in placing an insecticidal dust, such as eggs on the branches. combination, and plants that are stressed, bendiocarb, in the nest entrance at Encarsia can be used along with fatty ■ Control Sticky grease bands (see for whatever reason, may fall prey to dusk when the wasps have stopped acids, which do not affect it. Other p.52), placed around the trunk in mid- several viruses at once. There are several f lying for the night. pesticides, such as those used for cabbage fall, will prevent females from climbing means of transmission, the most common worm (see above), are harmful to Encarsia the tree. Newly hatched caterpillars being sap-sucking insect vectors. Waterlogging and, in any case, may give poor control can be controlled by spraying with Whitef ly, aphids, thrips, and leaf hoppers if a resistant strain is present. Several deltamethrin or lambda-cyhalothrin are a few examples. Nematodes and fungi ■ Crops affected Any. applications at five-day intervals are at bud burst. can also be virus vectors. ■ Symptoms Foliage wilts and yellows; needed even for susceptible strains. in extreme cases f lowers may also Thiacloprid can be used on greenhouse Wireworm In most cases, viral infection is non- wilt. Yellowed leaves fall prematurely. eggplants, peppers, and tomatoes. persistent, meaning that the virus cannot Inspection of the roots may reveal ■ Crops affected Root vegetables survive for long outside its host. An deterioration; the outer skin may peel White blister and seedlings, lettuce. insect can acquire a virus after feeding and can often be stripped easily from ■ Symptoms Seedlings are killed on a plant, but the virus has a window the root core. ■ Crops affected Brassicas, oyster and stems are severed just below soil of only a few seconds or minutes during ■ Causes Overwatering, excessive plants, and scorzonera. level. Potato tubers and carrots are which it must be passed on to another rainfall, or poor drainage may all be ■ Symptoms Plants develop white, extensively tunneled in late summer. host, otherwise it dies. Other viruses, implicated, singly or together. chalky, blisterlike pustules, usually on Slender, orange-brown, wormlike however, are persistent. The insect may ■ Control Attempt to improve soil lower leaf surfaces, with corresponding larvae, up to 1in (25mm) long, with pass it on for hours after feeding and may conditions and avoid overwatering. sunken, yellowish areas above. Tissues three pairs of short legs near the head even carry the virus for rest of its life. On heavy soils, make sure that a distort. end may be found in the soil or in large area of soil is lightened by the ■ Causes The fungi Albugo candida the tubers. They have a small but Viruses can also be transmitted by incorporation of large quantities of on brassicas, and Pustula tragopogonis on distinctive protuberance at the rear handling plants; by grafting (so-called grit and bulky, well-rotted organic oyster plants and scorzonera. A. candida end of the abdomen. graft-transmissible viruses); by handling matter before planting. The application can persist on hosts such as wallf lowers ■ Causes The larval stage of click tubers, bulbs, and corms; and during of a foliar feed can help to counteract (Erysimum), honesty (Lunaria), and beetles. There are several species, routine operations such as pruning, the effects of slight or temporary shepherd’s purse (Capsella bursa-pastoris), including Agriotes lineatus, A. obscurus, disbudding, or pinching out. waterlogging; it stimulates root while P. tragopogonis affects some A. sputator, and Athous haemorrhoidalis. ■ Control None available. Remove production to replace those lost. members of the daisy family. They occur most commonly in plots and dispose of affected plants promptly. ■ Control Remove all affected plants that have been newly converted from Wash hands and tools thoroughly Whiptail of brassicas: see Molybdenum promptly. Avoid overcrowding and the grassland. If the ground is kept in after handling infected plants. Do def icienc y. associated stagnant, humid air around cultivation, they will decline steadily not introduce plants of a similar type White rot: see Onion white rot. the plants, which encourages fungi over a three- or four-year period. onto sites that have previously supported to proliferate. When watering, direct ■ Control Dig up potato tubers as infected plants. Control vectors, Whiteflies and water onto the soil, not the plants, to soon as they mature to reduce damage. and control weeds, which may be cabbage worm avoid washing spores into the soil. There are no chemical controls alternative hosts. Do not propagate Do not grow alternative host plants available to amateur gardeners for the from infected plants. Where possible, ■ Crops affected Brassicas, okra, nearby. Brussels sprout ‘Bridge F1’ control of wireworms. choose resistant cultivars and buy pepper, sweet potato, tomato, cucurbits, shows a degree of resistance. There plants that are certified as virus-free. and many other glasshouse fruits and are no chemical controls available for Woolly aphid vegetables. use by the amateur gardener. Walnut blotch ■ Symptoms Small insects, about ■ Crops affected Apple. 1⁄12in (2mm) long, f ly up when disturbed Wind damage ■ Symptoms A woolly, white waxy ■ Crops affected Walnut. from beneath the leaves (see p.250). growth occurs on the bark of apple ■ Symptoms Leaves develop necrotic Adults have white wings. They lay ■ Crops affected Any. trees in late spring and summer. It is brown blotches and fall prematurely. their eggs beneath the leaves and these ■ Symptoms Leaves appear scorched, and secreted by blackish-brown aphids. Similar blotches appear on the fruits, hatch into f lat, oval, scalelike nymphs. one side of a plant is often more severely They often cluster around old pruning turning them from green to black. The final nymphal stage is sometimes affected than the other. Most damage wounds and cracks or splits in the bark. ■ Cause The fungus Gnomonia leptostyla. called a pupa, and is plumper, often occurs on the side of the prevailing wind. Later in the summer, they migrate It overwinters on fallen leaves. with hairs or waxy white secretions If winds are salt-laden, the damage is to young branches and cause knobby ■ Control Gather up and dispose of on the upper surface. Both nymphs exacerbated and the plant may die back swellings to develop. If these galls split affected fallen leaves. There are no and adults excrete sticky honeydew, or die completely. Where strong winds in frosty weather, they can form an chemical controls available. which drops onto the leaves and is are persistent, as they often are in coastal entry point for canker (see p.253). host to sooty molds. areas, for example, trees may develop a ■ Cause A sap-sucking aphid, Eriosoma Walnut leaf blight ■ Causes There are two important lop-sided growth habit; this is known as lanigerum. It overwinters as immature pest species: the cabbage worm (or “krumholtz” or wind-training, where nymphs beneath loose bark. ■ Crops affected Walnut. whitef ly), Aleyrodes proletella, and the they grow away from the prevailing wind. ■ Control Spray as soon as seen with ■ Symptoms Small, angular black spots glasshouse whitef ly, Trialeurodes ■ Cause Wind. The effects of wind are deltamethrin, lambda-cyhalothrin, on leaves and leaf stalks. It also similarly vaporariorum, which may infest outdoor made worse if wind tunnels are present or thiacloprid. Heavy infestations are affects the fruit. plants in warm summers. The cabbage (where wind speeds up when funneled difficult to control. ■ Cause The bacterium xanthomonas worm has several generations over the between two walls, for example) or if arboricola pv. juglandis. summer, and overwinters as an adult. windbreaks are removed. ■ Control Remove affected leaves as The glasshouse whitef ly breeds ■ Control Construct a shelter or plant soon as they are detected. There are continuously throughout the year under or erect windbreaks (see pp.12–13) to no chemical controls available. glass, but it will not survive winters in filter the wind. Prune out dead stems to cold areas outdoors. prevent secondary infections setting in. Wasps ■ Control On brassicas, light infestations can be tolerated. Treat heavy infestations Winter moth ■ Crops affected Ripe, sugar-rich fruits. on brassicas with deltamethrin, lambda- ■ Symptoms Soft inner tissues of cyhalothrin, fatty acids, or pyrethrum. ■ Crops affected Tree fruits. fruits are eaten out, eventually creating Several treatments at weekly intervals ■ Symptoms Leaves are bound together large hollow cavities. On relatively may be necessary with organic sprays. with silken threads to form a nest for soft-skinned fruits, wasps are capable yellow-green caterpillars with pale of initiating damage; on tougher-skinned

INDEX 265 INDEX Page numbers in bold indicate main recommended cultivars 179 bean fly 252 blossom thinning 160, 160 references; italic numbers refer to the rootstocks 153, 153, 174–75 bean trenches 95, 95 blossom wilt 252 illustrations thinning 177–78 beans bluebells 50 tree forms 152, 152, 174 blueberries 148, 206, 225, 225 A watering 177 in containers 36 apricots 148, 149 harvesting and storing 73, 97 in containers 35 acid soils 18 buds 165 saving seed 61, 61 crop yields 243 nutrient deficiencies 17 crop yields 243 sowing and planting 96–97, 97 problems 225, 248 see also pH values harvesting and storing 196 supports 95–96, 96 soil 207, 225 planting 196 wind damage 12 bok choy 74, 123, 125–26, 240, aeration, soil 15 pollination 156, 157, 196 see also individual types of bean 242, 247 alder hedges 13 problems 196, 248 bed system 32–34, 32–34 bolting 252 alkaline soils 18–19 protection 196 beech hedges 13 leafy vegetables 123, 123 pruning and training 167, 170, 196 bees 156, 157 onions 89, 91 nutrient deficiencies 17 recommended cultivars 196 beets 74, 82, 83, 85 salad crops 101, 101 see also pH values routine care 196 chlorosis 19 bone meal 21 almonds 148, 149, 165, 205, site and soil 196 crop planner 239 borage 23, 139 243, 248 thinning 196 crop yields 242 borders, growing fruit and alpine strawberries 211, 214, 214 tree forms and rootstocks 196 harvesting and storing 73, 84, 85 vegetables in 27–28 altitude 11, 207 arches problems 85, 247 boron 17 amaranth 74, 123, 124, 125, 238, apple cordons 177 recommended cultivars 85 deficiency 17, 17, 252 242, 247 cane fruits 216 routine care 85 botrytis 49, 51, 207, 250, 252 American cress 74, 101, 105, 239, Artic raspberries 215 site and soil 82, 85 box hedges 28 242, 247 artichoke bud rot 251 sowing 60, 65, 69, 83, 85 boysenberries 215, 215 American gooseberry mildew artichokes 75, 129, 133 benching, greenhouse 45 bracken, as insulation 48, 73 210, 251 crop planner 239 bergamot 140 brambles 49, 50 ammonia 20, 22 crop yields 242 biennial bearing, tree fruits 160 brandling worms 26, 26 ammonium nitrate 18 harvesting 132, 132, 133 big bud mite 252 brassicas 76–81 anaerobic composting 26 problems 247, 249 bindweed 50 boron deficiency 17 angelica 139 propagation 129, 130, 131 biological pest control 52, 52 buying transplants 70 animal manure 22, 22, 41 see also Chinese artichokes; birds 51, 52, 252 clubroot 18, 77 anthracnose 251 Jerusalem artichokes protecting crops 77, 161, 192, continuity of cropping 76 aphids 51, 52, 251 arugula 75, 101, 102, 103, 240, crop rotation 31, 31, 76 black bean aphid 252 242, 248 209, 209, 213 fertilizers 76 lettuce root aphid 257 asparagus 74, 129, 133 bitter fruits 252 germination rate 69 mealy cabbage aphid 257 crop planner 238 bitter pit 250, 252 hardiness 10 pea aphid 258 crop yields 242 bittercress, hairy 50 harvesting and storing 77 plum leaf-curling aphid 250, 259 harvesting 133 black bean aphid 252 intercropping 71 root aphid 261 problems 133, 247 blackberries 148, 206, 215–18, 215 problems 247 rosy apple aphid 261 propagation 130, 130 protecting 77, 77 woolly aphid 264 recommended cultivars 133 crop yields 243 seed 61 apple canker 163 routine care 133 problems 248 site and soil 76 apple powdery mildew 251 site and soil 133 pruning and training 210, sowing 62, 76–77 apple sawfly 251 sowing and planting 133 transplanting 76–77, 76 apple, pear, and olive scab 250, 251 asparagus beans 95, 238, 242 216, 217–18 watering 77 apple sucker 251 asparagus beetle 251 soil 206 see also individual types of brassica apples 148, 149, 174–80 asparagus peas 98, 238, 242 black currant gall borer 252 broadcast sowing buds 165 black currants 148, 206, 223–24, 223 outdoors 67, 68 chlorosis 19 B crop yields 243 under cover 63, 64, 64 in containers 35 harvesting 224 broccoli, sprouting 74, 76, 81 cordons 171, 174, 176–77 bacteria, in soil 14, 18 planting 208, 223, 223 crop planner 240 crop yields 243 bacterial canker 163, 165 problems 224, 248 crop yields 242 espaliers 171, 174 badgers 251 propagation 224 harvesting 81 fans 174 Ballerina apple trees 177, 177 pruning and training 210, problems 81, 247, 248 fertilizers 161, 177 bark chips, paths 34 recommended cultivars 81 frost damage 157 barn cloches 46, 46 223–24, 224 routine care 81 fruiting habits 175 barriers recommended cultivars 224 site and soil 81 harvesting and storing 178, 178 routine care 224 sowing and planting 81 mulching 177 artificial windbreaks 13, 13 site and soil 206, 223 staking 76, 77 pest control 52, 52, 187, 187 carrot fly protection 84, 84 blackfly 249 see also Chinese broccoli planting 175 base dressings, fertilizers 20, 21 blanching brown rot 253 pollination 156, 175, 180 basil 138, 141, 142, 238 chicory 102 brown scale 253 problems 248 bay trees 141, 142 stem vegetables 120, 120 Brussels sprouts 74, 76, 78 pruning and training 165, 167, bean beetle 251 blight 250 crop planner 239 block planting crop yields 242 169, 170, 175–77, 176 celery 120 harvesting 78 corn 108, 109 blood, dried 21, 22 blood, fish, and bone meal 21, 22 blossom end rot 252

266 INDEX intercropping 102 sowing 60, 61, 62, 65, 67, 68, choy sum see flowering greens corn smut 263 problems 78, 247 83, 86 chromosomes, tree fruits 156 cotton lavender 28, 140 recommended cultivars 78 cilantro 138, 141, 143 couch grass 38, 39, 49, 50 routine care 78 spacing 68 citrus fruits 148, 234–35, 234, 249 cranberries 148, 226, 226, 243, 249 site and soil 78 thinning seedlings 68 clamping 73 cress see American cress; mustard and sowing and planting 78 catch crops 29, 69, 71 clay soils 11, 14, 14, 15 staking 76, 77 leafy vegetables 124 cress wind damage 12 salad crops 102 brassicas 76, 77 crop planner 238–40 buds, fruit trees 164–65, 164 caterpillars 51, 52, 76, 250, 253 digging 37 crop rotation 31, 31 bullaces 185 cauliflowers 74, 76, 80 lime and 18 bullfinches 161, 209 crop planner 239 reducing alkalinity 19 bed system 33 bush fruit trees 152, 152, 206 crop yields 242 watering 53 brassicas 31, 31, 76 pruning 166–68, 166–68 harvesting 80 climate 10–11 legumes 95 butter beans 75, 95, 99, 238, 242 intercropping 102 microclimates 10, 12 root vegetables 82–83 buttercup, creeping 49, 50 problems 80, 247 cloches 12, 43, 46–47, 46–47 weeds and 82–83 recommended cultivars 80 clubroot 18, 31, 49, 51, 77, 82, crop yields 242–43 C routine care 80 250, 254 cross-pollination 156 site and soil 80 coastal sites 11, 12 crown rot 254 cabbage, Chinese see Chinese sowing and planting 60, 66, 80 codling moth 52, 187, 250, 254 crumb formation, soil 15, 18 cabbage celery 74, 120, 120, 121, 239, coir-based composts 64 cucumber mosaic virus 250, 254 242, 247 cold frames 30, 43, 45–46, 45 cucumbers 74, 114, 117–18 cabbage root fly 52, 76, 77, celery leaf miners 253 hardening off plants 45, 65 in containers 114–15 77, 253 celery root 74, 120, 122, 239, sowing seed in 62 crop planner 239 242, 247 cold weather 10–11 crop yields 242 cabbage white butterfly 51 Ceylon spinach 123, 125, 239, collars, brassicas 77, 77 harvesting 116, 118 cabbage whitefly 250 242, 247 Colorado potato beetle 254 pollination 116 cabbages 74, 76, 78–79 chalk, crushed 19 comfrey 21, 23, 51 problems 118, 247 chalky soils 14, 14 companion planting 84 protection 115 crop planner 239 chamomile 139 compost 22, 24–26, 24–26 recommended cultivars 117–118 crop yields 242 chard see Swiss chard composts routine care 118 harvesting and storing 73, chemicals for containers 36, 36 site and soil 118 pest control 52 for seedlings 64 sowing and planting 62, 114, 118 73, 79 weedkillers 50 sowing seed 63–64 supports 115 problems 79, 247 cherries 148, 149, 189–92 compound fertilizers 20, 21 cucurbits 114–19 recommended cultivars 79 buds 165 containers 35–36 fertilizers 115 routine care 79 crop yields 243 cucurbits in 114–15 frost damage 10 site and soil 79 feeding and mulching 190, 192 fruiting vegetables 110 hardening off 114 sowing and planting 79 harvesting and storing 190, herbs 138, 139 harvesting and storing 116 cages 30, 52, 161, 209, 209 leafy vegetables 124, 124 planting out 114, 115 calabrese broccoli 74, 76, 79, 239, 190, 192 root vegetables 83 pollination 116, 116 242, 247 planting 189, 191 salad crops 102 routine care 115–16 calcium 17, 72 pollination 156, 189, 190, 191 soft fruit in 206, 206 site and soil 114–15 deficiency 110, 253 problems 190, 192, 248–49 for sowing seed 62, 63 sowing 114 cane fruits 206, 215–18 protection 189, 190, 190, 192 watering 72 supports 115, 115 harvesting and storing 218, 218 pruning and training 167, 170, copper 17, 19 watering 116 planting 215–17, 215 deficiency 254 cultivators 40, 40, 50, 55–56, 56 propagation 218 189–90, 191–92, 192 coral spot canker 210, 254 curly kale see kale pruning and training 216, recommended cultivars 190, 192 cordons 152, 152 currant, flowering 13 site and soil 15, 189 apples 171, 174, 176–77 cut-and-come-again plants 76, 102, 217–18, 217 sour cherries 191–92 grape vines 227, 228–29, 123, 123 recommended cultivars 218 sweet and duke cherries 189–90 cutting tools 57 routine care 218 tree forms and rootstocks 189, 191 228–29, 232 cuttings, herb 140 site and soil 215 watering 190, 192 pears 171, 182 cutworms 254 supports 215, 216 cherry plums 185 planting 159, 159 see also individual types of cane fruit chervil 138, 139, 141, 142 plums 185, 186 D cane spot canker 253 chicken manure 22 pruning 171, 172, 173 canker 51, 163, 164, 253 chickweed 50 red currants 221–22, 221 Daktulosphaira vitifolii 227 mulberry canker 258 chicory 74, 101, 102, 102, 103, as windbreaks 13 damping down, greenhouses 72 parsnip canker 82, 258 239, 242, 247 wires 162 damping off 254 capsid bugs 253 chile peppers 74, 108, 110, 111–12, corn 75, 108, 111 damsons 148, 185, 185 cardoons 75, 129, 131, 133–34, 239, 242, 248 block planting 108, 109 dandelions 49, 50 239, 242, 247 Chinese artichokes 129, 131, 132, crop planner 240 deer 51, 161, 254 carpet, weed control 49, 49 134, 239, 242, 247 crop yields 242 dibbers 56, 56, 69, 69 carrot fly 51, 52, 68, 84, 84, Chinese broccoli 123, 126, 239, harvesting 110, 110, 111 dieback 255 250, 253 242, 247 intercropping 90, 124 carrots 75, 82, 83, 85–86 Chinese cabbage 74, 123, 126, problems 111, 248 gooseberry dieback 256 companion planting 84 239, 242, 247 recommended cultivars 111 digging 37–39, 37–39 crop planner 239 Chinese gooseberries 148 routine care 111 dill 138, 141, 143 crop yields 242 chip-budding 154, 154–55 site and soil 111 diseases 51 harvesting and storing 73, 84, 86 chives 65, 141, 142–43 sowing and planting 62, 63, 68, problems 86, 247 chlorine 17 rainfall and 11 recommended cultivars 86 chlorophyll 17 69, 108–09, 111 soil acidity and 18 routine care 86 chlorosis 17, 19, 254 corn salad 75, 101, 102, 104, 239, weeds and 49 site and soil 82, 86 chocolate spot 254 242, 247

division pears 182, 183 Florence fennel see fennel INDEX 267 herbs 140 planting 159 flowering greens 239, 242, 247 perennial vegetables 129–31, plums 185, 186, 187 flowers, structure 156 crop yields 242 130–31 pruning 173, 173 foliage, wind damage 12 harvesting and storing 73, 93 red or white currants 222, 222 foliar feeds 21 intercropping 90 docks 39, 49, 50 tree fruits 152, 152 foot rots 255 planting 90, 90 dolomitic limestone 18 wires 162 forcing chicory 102 problems 93, 247 dormancy, seed 69 farmyard manure 22, 22, 41 forks 37, 37, 55, 55, 56 recommended cultivars 93 double digging 38–39, 39 fava beans 75, 95, 98, 238 freezing herbs 140 routine care 93 downy mildew 91, 250, 255 crop planner 238 French beans 75, 95, 95, 99 site and soil 92 drainage 16, 16 crop yields 242 sowing and planting 92 harvesting 98 crop planner 238 germination 61, 69 containers 36, 36 problems 98, 247 crop yields 242 gherkins 74, 117–18, 239, 242 raised beds 34 recommended cultivars 98 germination rate 69 glass tree fruits 149–50 routine care 98 harvesting and storage 99 cloches 46, 46 dribble bars, watering cans site and soil 95, 98 problems 99, 247 cold frames 45 53, 53 sowing and planting 61, 62, 69, 98 recommended cultivars 99 greenhouses 44 drills, sowing seed 40, 40, 66, supports 96 routine care 99 glyphosphate 40, 50 67–68, 67 wind damage 12 site and soil 99 good King Henry 143 drip hose 54, 54 feathered maidens 149, 150 sowing and planting 69, gooseberries 148, 206, drought 11, 255 formative pruning 166, 166 219–20, 219 drying herbs 140 fences 96, 99 crop yields 243 duke cherries 189–90 deer-proof 161 supports 96 harvesting 220 dust mulches 72 fixing wires to 162 French drains 16 planting 219–20, 219 dwarf pyramid fruit trees planting tree fruit against 159, frit fly 255 problems 220, 249 apples 176 frogs 52 propagation 220 pears 182, 182 159 frost 10–11 pruning 210, 220, 220 pruning 170–71 rabbit-proof 161 damage to crops 255 recommended cultivars 220 as windbreaks 13 effects on soil 37 routine care 220 E fennel, Florence 75, 120, 122, 239, frost pockets 11, 11, 12 site and soil 219 242, 247 protective materials 48, 73 gooseberry dieback 256 earthworms 15, 18, 22, 37, 39, 41 fennel (herb) 138, 139, 141, 143 soft fruits 207, 209, 218 gooseberry sawfly 250, 256 edema 255 fertility, soil 14 tree fruits 149, 157 goosefoot 50 eggplants 75, 108, 108, 112 fertilizers 17, 20–21, 20, 21, 22 fruit 147–237 gourds, ornamental 114 cane fruits 218 crop rotation 31 grafting, tree fruits 154–55, crop planner 238 for containers 36 crop yields 243 154–55 crop yields 242 cucurbits 115 mulching 41 granite chips, paths 34 harvesting 112 leafy vegetables 124 problems 248–49 grape vines 148, 227–33 problems 110, 112, 247 pests and diseases and 51 rainfall and 11 crop yields 243 recommended cultivars 112 plums 186–87 soft fruits 206–26 fertilizers 161 removing sideshoots 110 seedlings 65 soils 15 harvesting 230, 230, 231 routine care 112 soft fruits 209 tender fruits 234–37 outdoors 231–32 site and soil 112 strawberries 213 tree fruits 149–213 pollination 230 sowing and planting 62, 108, 112 tree fruits 161 wind damage 12 problems 230, 230, 233, 249 Egyptian onions 94, 240, 247 vegetables 72 winter protection 10, 11 pruning and training 227, Encarsia wasps 52, 52 figs 148, 149, 156, 197–99 see also individual types endive 74, 101, 104 in containers 199, 199 228–29, 228–29, 231, 232 catch crops 102 crop yields 243 of fruit recommended varieties 233 crop planner 239 frost protection 48 fruit fly 256 rootstocks 227 crop yields 242 harvesting 199 fruiting vegetables 108–13 shanking 262 problems 104, 247 planting and root restriction thinning 230, 230, 231 transplanting 102 in containers 110 under cover 227, 228–30 Epsom salts 161 197, 197 fertilizers 110 gray mold 49 equipment 55–59, 55–59 pollination 197 harvesting 110 green manures 23, 23, 209 espaliers 152, 152 problems 199, 249 mulching 109, 109 green onions 74, 89, 93, 240, 247 apples 171, 174 propagation 199 problems 110 greenhouses 30, 43–45, pears 171, 181 pruning and training 197–99, 198 routine care 110 43, 44 planting 159 recommended cultivars 199 saving seed 110 damping down 72 pruning 171, 172, 173 routine care 199 site and soil 108 grape vines 228–30 as windbreaks 13 site and soil 197 sowing and planting 108–09 heating 44, 45 wires 162 tree forms 197 supports 109, 110 sowing seed in 62 exposure 11 winter protection 199, 199 watering 110 ventilation 44, 44 filberts 148, 149, 156, 203, 243, 249 fungal diseases 51 greens 123 F fireblight 255 fungi, in soil 14 see also brassicas; flowering greens fish meal 21 fungicides 11, 64, 207 grit, paths 34 F1 hybrids 60 flame guns 50 fusarium 91, 256 ground elder 38, 49, 50 fans flat beds 32, 33, 33 fusarium wilt 256 groundsel 50 flea beetle 250, 255 growing bags 35, 43 apricots 196 fleece G fertilizers 36 cherries 189–90, 191, 192, 192 floating mulches 48, 48 planting crops in 36 peaches and nectarines 193–94, 194 protecting crops 52, 69 gages 185 soft fruit 208 salad crops 101, 101 garlic 74, 89, 92–93 tomatoes in 110 floating mulches 42, 47–48, 48 watering 72 crop planner 239 growing season, length of 10

268 INDEX guttering, sowing peas in 96–97, 97 inorganic fertilizers 20, 21 seedling crops 123–24 Malabar spinach 125, 239, 247 guyot system, grape vines 227, inorganic mulches 42, 42 site and soil 123 manganese 17, 19, 22 insects sowing and planting 123 231, 232 watering 124 deficiency 17, 257 pests 51–52 leather jackets 257 manures 20, 22–23, 22–23 H pollination 156, 157 leek rust 250, 257 insulation leeks 74, 89, 93 digging soil 38 half-standard trees cold frames 46 crop planner 239 lime and 19 apples 174 greenhouses 44 crop yields 242 mulches 41 pears 182 natural materials 48, 73 germination rate 69 marigolds 140 plums 186 intercropping 29, 71 harvesting 93 marjoram 138, 139, 141, 144 pruning 166 leafy vegetables 124 planting 90, 91 marrows 75, 119 onion family 90 problems 93, 247 crop planner 240 halo blight 256 salad crops 102 recommended cultivars 93 crop yields 242 hand forks 55, 56 intersowing 69, 69 routine care 93 harvesting and storing 73, 116, 119 hanging baskets 35, 206, 211 iron 17, 19, 22 site and soil 93 problems 119, 247 hardening off 45 deficiency 17, 256 sowing and planting 65, 66, recommended cultivars 119 irrigation systems 54, 54 routine care 119 cucurbits 114 bed system 32 89, 93 site and soil 119 seedlings 62, 65 tree fruits 160, 160 legumes 95–100 sowing and planting 63, 68, harvesting see individual types Japanese bunching onions 89, 93, of fruit and vegetables 240, 242, 247 crop rotation 31, 31, 95 69, 119 hawthorn hedges 13 Japanese mustard spinach 74, 76, harvesting 97 meadow grass, annual 50 hazel hedges 13 101, 105, 239, 242, 247 nitrogen-fixing nodules 95, 95 mealy cabbage aphid 257 hazelnuts 148, 149, 154, 156, 203, Jerusalem artichokes 75, 129, 135 routine care 97 mealybugs 257 243, 249 crop planner 238 saving seed 97 measuring tools 57 heating crop yields 242 site and soil 95 medlars 148, 149, 201, 243, 249 bottom heat 62 harvesting 132, 132, 135 sowing 96–97 melons 74, 114, 118 greenhouses 44, 45 problems 135, 247 supports 95–96, 96 hedgehogs 52 propagation 129, 131 lemon balm 141, 143 crop planner 240 hedgerow system, cane fruits 216 June drop 160 lemon grass 141, 143–44 crop yields 242 hedges kale 74, 76, 80–81 lettuce 75, 105–06 harvesting and storing 116, 118 microclimates 10 crop planner 239 bed system 32 pollination 116 planting 13 crop yields 242 bolting 101 problems 118, 247 windbreaks 13 harvesting 80 crop planner 239 protection 115 heeling in 70, 150, 150 problems 80, 247 crop yields 242 recommended cultivars 118 herbs 137–45 recommended cultivars germination rate 69 routine care 118 in containers 35, 36, 138, 139 hardiness 10 seed 61, 61 drying 140 81 harvesting 105 site and soil 118 freezing 140 routine care 80 intercropping 102 sowing and planting 114, 118 harvesting 139 site and soil 80 problems 105, 247 supports 115 pinching out 139 sowing and planting 76, 80 recommended cultivars mesh fences 13, 13 propagation 140, 140 kidney beans 75, 95, 238, 242 mibuna greens 101, 106, 240, site and soil 138–39 kitchen gardens 28–29 105–06 242, 247 heritage seed 60 kiwi fruit 148, 156, 235, 235, 249 routine care 105 mice 46, 257 herringbone drainage 16 knives 57 saving seed 102 microclimates 10, 12 hoes 55, 56, 56 knot gardens 139 site and soil 105 micronutrients 17 hoe mulching 72, 72 kohlrabi 74, 76, 81, 239, 242, 247 sowing and planting 62, 67, 69, microorganisms, in soil 14, 18 weed control 50 mildew honey fungus 256 L 70, 101, 102, 105 American gooseberry mildew hoof and horn 21, 22 spacing 68 hornbeam hedges 13 lacewings 52 watering 11 210, 251 horse manure 22 ladybugs 52 lettuce root aphid 257 apple powdery mildew 250, 251 horse tail 49, 50 lamb’s lettuce 75, 239, 242 light 10, 10 downy mildew 91, 250, 255 horseradish 138, 139, 141, 143 landscape fabric lima beans 75, 95, 99, 238, 242, 247 powdery mildew 260 hoses 53, 53 lime-induced chlorosis 17 minarette apple trees 176 hoverflies 52 herb gardens 139 limestone 18, 19 mint 138, 139, 139, 140, 141, humus 14, 15, 21, 24 mulches 34, 34, 42 liming soil 15, 18–19, 19, 76 144, 247 hungry gap 123 planting through 77 liquid fertilizers 21, 51 mint rust 257 hurdles, willow 13 lavender 28, 138, 140 loam 14 mizuna greens 74, 76, 101, 106, hybrid berries 148, 206, 210, leaf mold 26 location 10 240, 242, 247 215–18, 249 leaf spots loganberries 215, 215, 216 modified Lorette system, tree fruits hydrated lime 19 bacterial 256 loppers 56, 57, 163 171, 171 hygiene, sowing seed 64 fungal 257 lovage 139, 141, 144 molybdenum 17 leafy vegetables 123–28 lupins, green manures 23 deficiency 17, 257 I, J, K bolting 123, 123 mulberries 148, 149, 171, 202, in containers 124, 124 M 243, 249 ice plant 75, 101, 105, 239, fertilizers 124 mulberry canker 258 242, 247 harvesting 124 magnesium 17, 18, 22, 161 mulching 41–42, 41–42 intercropping 124 deficiency 250, 257 cucurbits 115–116 Indian spinach 242 overwintering 124 fruiting vegetables 109, 109 routine care 124 maiden whips 149, 150 hoe mulching 72, 72 formative pruning 166, 166 inorganic mulches 42, 42 mulched paths 34, 34 mail order, plug plants 70, 70 no-digging system 39, 40 organic matter 14, 22, 41–42, 41

INDEX 269 perennial vegetables 129 O passion fruit 148, 235–36, pelleted seed, sowing 67 potatoes under 84 235, 249 peppers 74, 108, 111–12 strawberries 211, 212, 212 offsets, perennial vegetables 130–31 tree fruits 158, 159, 161, 161 okra 74, 108, 112, 240, 242, 247 paths 29 crop planner 240 weed control 49, 49, 50 olives 148, 236–37, 237, 249 bed system 33, 34 crop yields 242 multiblock sowing 65, 65 onion family 89–94 mulched paths 34, 34 harvesting and storage 73, multigerm seed 60 mushroom compost 22, 22 bolting 91 pea and bean weevils 258 111–12 mustard and cress 75, 101, 106 harvesting 90–91, 91 pea aphid 258 problems 110, 112, 248 crop planner 240 problems 91 pea leaf and pod spot 258 recommended cultivars 112 problems 247 site and soil 89 pea moth 250, 258 removing sideshoots 110 sowing 65, 67, 68 sowing and planting 89–91, 89–91 pea thrips 258 routine care 111 mustard greens 74, 123, 124, 127 onion fly 68, 91, 258 peach leaf curl 52, 250, 258 site and soil 111 crop planner 240 onion neck rot 91, 258 peaches 148, 149, 193–95 sowing and planting 62, 64, 70, crop yields 242 onion thrips 91, 258 green manures 23 onion white rot 91, 250, 258 buds 165, 193 71, 108, 111 problems 247 onions 74, 92 crop yields 243 supports 109 myrobalans 185 bolting 89, 91 fertilizers 161 perennial vegetables 129–35 companion planting 84 growing from seed 195 forcing 132, 132 N crop planner 240 harvesting and storing 195 harvesting 132 crop yields 242 planting 193 mulching 129 nectarines 148, 149, 196 harvesting and storing 73, 73, pollination 156, 157, 193 ornamental crops 129 buds 165 problems 195, 249 propagation 129–31, 130–31 crop yields 243 91, 92 protection 193, 195 routine care 129 harvesting and storing 195 intercropping 90 pruning 167, 170, 193–94, 194 site and soil 129 planting 193 problems 92, 247 recommended cultivars 195 pests 51–52 pollination 193 recommended cultivars 92 routine care 194–95 crop rotation 31 problems 195, 249 routine care 92 site and soil 193 mulches and 42 pruning 167, 193–94, 194 sets 89, 89, 90 thinning 195 pesticides 12 recommended cultivars 195 site and soil 92 tree forms and rootstocks 193 rainfall and 11 routine care 194–95 sowing and planting 62, 65, pear and cherry slugworm 259 tree fruits 161 site and soil 193 pear canker 163 weeds and 49 thinning 195 89–90, 90–91, 92 pear leaf blister mite 259 pH values, soil 17, 18–19, 18 tree forms and rootstocks 193 thinning 68, 89 pear midge 259 clubroot and 76 oregano 141 pear scab 251 crop rotation 31 neglected trees, pruning 168, 168 organic fertilizers 20, 21 pears 148, 149, 181–85 leafy vegetables 123 nematodes 52, 52 organic matter buds 164, 165 legumes 95 nematodes 31, 49, 51, 82, 255 compost 24–26 chlorosis 19 root vegetables 82 manures 20, 22 in containers 35 soft fruits 207 potato cyst nematode 260 mulches 14, 22, 41–42, 41 cordons 171, 182 tree fruits 150 root knot nematode 261 in soil 14, 15, 21 crop yields 243 pheromone traps 187 stem and bulb nematode 91, Oriental vegetables 76, 123 espaliers 171, 181 phosphate 20, 21 ornamental crops 129, 139 fertilizers 161 phosphorus 17 262–63 Oxalis 50 harvesting and storing 183 deficiency 20 netting oyster plant 75, 82, 84, 86, 240, planting 182 fertilizers 20, 21 242, 248 pollination 156, 157, 181–82, 184 photosynthesis 10 protecting crops 52, 209 problems 183, 249 phytophthora 208, 259 supporting peas and beans, 96 P, Q pruning and training 165, 167, pickling onions 93, 240, 242 nettles 38, 39, 49, 50 pineapple 148, 236, 236, 249 New Zealand spinach 75, 123, pan, soil 16, 16 169, 170, 182, 182, 183 pipes, drainage systems 16 127-28, 240, 242, 247 parsley 27, 138, 141, 144 recommended cultivars 184 planning 27–30, 30 nitrogen 17, 18, 72 rootstocks 181 bed system 33 compost 24–25 crop planner 240 routine care 182–83 crop planner 238–40 crop rotation 31 germination rate 69 thinning 183 plastic deficiency 258 protecting 140 tree forms 152, 152, 181 cloches 46–47, 46, 47 fertilizers 20, 21 sowing 61, 65 peas 75, 95, 99–100 greenhouses 44 green manures 23 parsley root 75, 82, 86, 239, 242, in containers 36 polytunnels 44, 44 legumes and 95, 95 247 crop planner 240 plastic mulches 41, 42, 42 in manures 22 parsnip canker 82, 258 crop yields 242 floating mulches 47–48 and pests and diseases 51 parsnips 75, 82, 83, 86–87 green manures 23 strawberries 211, 212, 212 tree fruits 161 crop planner 240 harvesting and storing 73, 97, weed control 49, 49, 50 no-digging system 39–40 crop yields 242 plastic strap cladding 13, 13 nut trees 156, 203–05 germination rate 69 100 plug plants 63, 70, 70 nut weevils 258 harvesting and storing 73, 84, 87 problems 100, 247–48 plum fruit moth 52, 187, 259 nutrients 17–28 intercropping 102 recommended cultivars 100 plum leaf-curling aphid 250, 259 deficiency 17 problems 87, 247 routine care 100 plums 148, 149, 185–88 fertilizers 20–21, 22 recommended cultivars 87 saving seed 61, 61 buds 165 major nutrients 17 routine care 87 site and soil 100 cordons 171 in manures 22 site and soil 82, 86 sowing and planting 62, 67, crop yields 243 micronutrients 17 sowing and planting 60, 61, feeding and mulching 186–87 minor nutrients 17 96–97, 97, 100 harvesting and storing 187 testing 17 66, 67, 69, 69, 83, 86 spacing 68 planting 186 spacing 68 supports 95–96, 96 pollination 156, 157, 185–86, 187 wind damage 12 problems 187, 249 peasticks 96, 96 peat-based composts 64 peat soils 14, 14

270 INDEX pruning and training 165, 167, crop planner 240 red core 261 problems 88, 248 170, 186, 186, 187 crop yields 242 red spider mite 250, 261 recommended cultivars 88 harvesting and storing 73, red currants 148, 206, 207, routine care 88 recommended cultivars 188 site and soil 82, 88 rootstocks 185 116, 118 221–22, 222 sowing 88 thinning 187 problems 118, 248 crop yields 243 rye grass, green manures 23 tree forms 185 recommended cultivars 118 harvesting 222 watering 187 routine care 118 problems 249 S pollination site and soil 118 propagation 222 apples 175, 180 sowing and planting 118 pruning and training 210, sage 27, 138, 139, 141, 145 apricots 196 watering 116 salad crops 101–07 cherries 189, 190, 191 purslane 75, 101, 106–07, 221–22, 221–22 cucurbits 116, 116 240, 242, 248 recommended cultivars 222 bolting 101 peaches and nectarines 193 purslane, winter 101, 107, 240, routine care 222 catch cropping 71, 102 pears 181–82, 184 242, 248 site and soil 221 in containers 36, 102 plums 185–86, 187 pyramid fruit trees supports 221 cut-and-come-again 102 tree fruits 156–57, 156, 157 apples 176 replant diseases 31, 206–07, 261 extending the season 102 polytunnels 44, 44 cherries 192 reversion disease 261 intercropping 102 poorly formed fruits 259 pears 182, 182 rhubarb 75, 129, 135 saving seed 102 potagers 7, 27, 27, 28, 71 pruning 170–71, 170 crop planner 240 sowing 65, 101 potash 20, 21, 72 tree fruits 152, 152 crop yields 242 temperature requirements 101 potassium 17, 18 quicklime 19 forcing 132, 132 thinning 101 deficiency 259 quince leaf blight 260 problems 135, 248 transplanting 101–02 fertilizers 20, 21 quinces 148, 149, 200, 243, 249 propagation 130, 130 salad onions 69, 89 in manures 22 root aphid 261 salt, coastal sites 11, 12 tree fruits 161 R root cuttings 131, 131, 140 sandy soils 14, 14, 15 potato black leg 259 root knot nematode 261 brassicas 76, 77 potato blight 260 rabbits 51, 161, 161, 260 root rots 255 forking over 37, 37 potato common scab 18, 76, radicchio 102 root trainers 108 reducing alkalinity 19 250, 260 radishes 75, 76, 101, 107 root vegetables 82–88 watering 53 potato cyst nematode 260 carrot fly 84, 84 savory 141, 145 potato powdery scab 82, 260 catch crops 102 in containers 83 Savoy cabbages 11, 79 potato viruses 260 crop planner 240 crop rotation 31, 31, 82–83 sawfly, gooseberry 250, 256 potatoes 75, 82, 83, 87 crop yields 242 frost protection 48, 73 saws, pruning 56, 163 crop planner 240 germination rate 69 harvesting and storing 73, scab crop yields 242 harvesting and storing 107 apple, pear, and olive scab 250, harvesting and storing 73, 73, intercropping 102 73, 84 problems 107, 248 protection 83, 84 251 84, 87 recommended cultivars 107 soil and pH values 82 potato common scab 18, 76, planting 83, 83, 84, 87 routine care 107 sowing 83 pregerminating 83, 83 saving seed 102 rootballs, tree fruits 150 250, 260 problems 87, 248 site and soil 107 rootstocks 153, 153 potato powdery scab 82, 260 recommended cultivars 87 sowing and planting 67, 68, 69, apples 174–75 soil acidity and 18 routine care 87 apricots 196 scale insect 261 site and soil 82, 87 69, 101, 107 cherries 189, 191 scallions 74, 89, 94 potting composts 63, 64 spacing 68 division 129–31, 130–31 crop planner 240 powdery mildew 260 transplanting 101, 102 grafting 154–55, 154–55 crop yields 242 precision-treated seed 60 raincovers grape vines 227 harvesting 94 predators, pest control 52, 52 cherries 190, 190 peaches and nectarines 193 intercropping 90 pregerminated seed 60 peaches 195 pears 181 problems 94, 247 pregerminating potatoes 83, 83 soft fruits 209 plums 185 recommended cultivars 94 pricking out seedlings 62–63, rainfall 11, 53, 207 rose hedges 13 routine care 94 64–65, 64 raised beds 32, 33–34, 33 rosemary 138, 140, 141, 144–45 site and soil 94 prickly pears 148, 237, 237, 249 rakes 40, 40, 55, 55 rosy apple aphid 261 sowing and planting 60, 65, 94 primed seed 60 ramsons 50 rotation of crops see crop rotation Scandinavian system, cane fruits 216 propagation rape 23, 65 routine care 72 scions, grafting 154 cane fruits 218 raspberries 148, 206, 215–18, 215 runner beans 75, 95, 100 sclerotinia 250, 262 herbs 140, 140 crop yields 243 crop planner 238 scorch 10, 262 perennial vegetables 129–31, fertilizers 161 crop yields 242 scorzonera 75, 82, 84, 88, 240, harvesting 218 harvesting 100 242, 248 130–31 planting 215, 215, 216 problems 100, 247 screens, windbreaks 13 strawberries 214 problems 249 recommended cultivars 100 sea kale 129, 131, 131, 132, 135, tree fruits 153–55, 153–55 pruning and training 217, 217 routine care 100 240, 242, 248 propagators 62, 63, 63 site and soil 207, 215 site and soil 100 seasonal tasks 243–45 protected cropping 43–48 supports 216 sowing and planting 61, 69, seaweed 21, 22, 51 pruners 55, 56, 57, 163 raspberry beetle 250, 260 seed composts 63–64 pruning raspberry cane blight 260 96, 100 seed drills 40, 40, 66, 67–68, 67 cane fruits 217–18, 217 raspberry cane borer 217 supports 28, 96, 96 seed merchants 60, 61 soft fruits 210 raspberry leaf and bud mite 261 rusts 49, 261 seed sowers 56, 56, 67, 67 tools 163, 165 raspberry spur blight 261 leek rust 250, 257 seed tapes 60 tree fruits 162–73, 162–73 raspberry viruses 261 mint rust 257 seed trays 62, 63, 63 see also individual types of fruit red cabbage 73, 79, 239 rutabagas 74, 76, 82, 88 seedbeds 66–67, 70 pulpy fruits, saving seed 61 crop planner 240 pumpkins 75, 114, 118 crop yields 242 harvesting and storing 73, 84, 88

INDEX 271 seedlings nutrients 17–28 station sowing 66, 67, 68, 69 T fertilizers 65 organic matter 14, 15, 21 stem and bulb nematode 91, hardening off 62, 65 pH values 17, 18–19, 18 tarragon 141, 145 leafy vegetables 123–24 preparation 37–40 262–63 tayberries 215, 215 planting out 70–71, 70–71 seedbeds 66–67 stem vegetables 120–22 temperature pricking out 62–63, 64–65, 64 soil pan 16, 16 stepover, apple tree 176, 176 thinning 68, 68 soil profile 15, 15 stool system, cane fruits 216 effects of 10–11 structure 15 storing vegetables 73, 73 sowing under cover 62–63 seeds 60–69 texture 14 straw tender fruits 234–37 buying 60, 61 types 14, 14, 15 texsel greens 76, 81, 240, 242, composts 63–64 waterlogged soil 11, 16 as insulation 48, 73 germination 69 see also individual types of fruit mulches 41, 41, 42 248 saving 60, 61, 61 protecting strawberries 213, thinning soil preparation 40 and vegetable sowing outdoors 66–69, 66–69 soil-based composts 64 213 grapes 230, 230, 231 sowing under cover 62–65, sorrel 145 strawberries 148, 206, 211–14, salad crops 101 62–65 sour cherries see cherries seedlings 68, 68 storing 61 sowing 211 tree fruits 160, 160, 165 types of 60, 60 in containers 35, 206, 211, thrips 263 viability 61 catch crops 69 thyme 27, 138, 139, 141, 145 weeds 50, 66 intersowing 69, 69 211, 212, 213–14 tilth 40, 66–67 outdoors 66–69, 66–69 crop planner 240 tip burn 263 semiflat beds 33, 33 station sowing 66, 67, 68, 69 crop rotation 31 tomatillos 75, 108, 112–13, 240, sets, onions 89, 89, 90 successional sowings 29, 69 crop yields 243 242, 248 sewage sludge 22 under cover 62–65, 62–65 crown thinning 210, 213 tomato blotchy ripening 263 shading space sowing 66, 67, 68, 69 frost protection 209 tomato ghost spot 263 spacing vegetables 68, 71 harvesting and storing 214 tomatoes 75, 108, 113 cold frames 46 speedwell 50 mulches 211, 212, 212 buying transplants 70 greenhouses 44–45 spinach 75, 123, 128 planting 208, 212, 212 in containers 35, 110 shady sites 10, 29–30, 207 crop planner 240 pollination 213 crop planner 240 shallots 74, 89, 94 crop yields 242 problems 207, 214, 249 crop yields 242 crop planner 240 harvesting and storing 124, 128 propagation 214 frost damage 10 crop yields 242 intercropping 124 protection 213, 213 in greenhouses 43, 43 drying 91 problems 128, 248 pruning 210, 210 harvesting 113 intercropping 90 recommended cultivars 128 recommended cultivars 214 mulching 109 problems 94, 247 routine care 128 routine care 212–13 problems 110, 113, 248 storage 73 site and soil 128 runners 212, 213, 214 recommended cultivars 113 shanking of grapes 262 sowing and planting 67, 68, soil and site 15, 207, 212 removing sideshoots 109, shelter 11, 12–13, 12–13, strawberry blossom weevil 214 157, 207 69, 128 strawberry mats 213 110 shovels 37, 55, 55 spinach beet 74, 123, 124, 128, strawberry seed beetle 263 routine care 110, 113 silt soils 14, 14, 15, 37 strawberry viruses 263 saving seed 110 silver leaf 165, 262 240, 242, 248 subsoil 15, 15, 16, 16 site and soil 113 single digging 38, 38 spinach cress 240 successional sowing 29, 69 sowing and planting 61, 62, slate chips, paths 34 spinach mustard 123, 127, 248 brassicas 76 sloping sites, frost pockets 11, 11, 12 spindlebush fruit trees 152, 152 cucurbits 114 64, 113 slugs 42, 52, 250, 262 sugar peas 60 supports 109 snails 42, 52, 262 pears 182 sulfur 17, 19 tools 55–59, 55–59 soakaways 16 pruning 169–70, 169 summer pruning 171, 171 pruning 163, 165 soaker hose 54, 54 Spiraea ‘Arguta’ 13, 13 sunflowers 145, 240, 248 top-dressing, fertilizers 20, 21, soft fruits 206–26 splitting 262 sunshine 10, 10, 30 21 general care 209 sprays 53, 53, 57 superphosphate, triple 20 topsoil 15, 15, 16, 16 planting 208, 208 spring cabbage 239 supports 72 trace elements 17, 19, 21, 72 problems 206–07, 209 spring greens 76 brassicas 76, 77 training protection 209, 209 sprinklers 53–54, 53, 160, 160 cane fruits 215, 216 cane fruits 216, 217, 217 pruning 210 sprinter seeds 60 containers 36 soft fruits 210, 210 shelter 207 spur pruning, soft fruits 210 cucurbits 115, 115 tree fruits 162–73, 162–73 site and soil 206–07, 208 spur thinning, tree fruits 165 fruiting vegetables 109 see also individual types see also individual types of soft fruit squashes 114 grape vines 231 soil 14–16 crop planner 240 legumes 95–96, 96 of fruit acidity and alkalinity 18–19 crop yields 242 soft fruits 210 transplanting aeration 15 harvesting 116 staking tree fruits 158–59 bed system 32–34, 32–34 problems 248 training fruit 162–63 salad crops 101–02 compaction 32, 40 sowing 114 sweet Cicely 138, 140, 141, 145 seedlings 62–63, 64–65, 64, crop rotation 31 storage 73 sweet peas 29 digging 37–39, 37–39 summer squashes 117 sweet peppers see peppers 70–71, 70–71 drainage 16, 16, 149–50 supports 115 sweet potatoes 75, 82, 84, 88, trays fertility 14 winter squashes 118 240, 242, 248 fertilizers 20–21, 20, 21, 22 squirrels 213, 262 Swiss chard 27, 74, 123, 124, 128 seedlings 63 frost and 11 staking see supports crop planner 240 sowing seed 62, 63, 65, 65 liming 18–19, 19, 76 stale seedbeds 50, 66 crop yields 242 treated seed 60 manures 22–23, 22–23 standards intercropping 124 tree fruits 149–213 mulching 41–42, 41–42 citrus fruits 234 problems 128, 248 buds 164–65, 164 no-digging system 39–40 grape vines 227, 230 fertilizers 161 plums 186 forms 149, 152, 152 pruning 166 frost damage 157 general care 160–61 grafting 154–55, 154–55 in greenhouses 43

272 INDEX heeling in 150, 150 V–Z water loss, wind damage 12 willow hurdles 13 mulching 158, 159, 161, watering 53–54, 53–54 wilting 10 vegetable marrows see marrows winds 11, 12–13, 12 161 vegetables cane fruits 218 pests 161 containers 36, 72 damage 207, 264 planting 158–59, 158, 159 crop planner 238–40 cucurbits 116 pollination 156–57 pollination 156–57, 156, feeding 72 greenhouses 45 windbreaks 11, 12–13, 12–13, planting out 70–71 leafy vegetables 124 157 problems 246–64 mulching and 41 157, 207 pruning and training 162–73, root vegetables 82–88 soft fruits 209 windrock 217 seed and sowing 60–69 tree fruits 160, 160 windowboxes 35 162–73 watering 72 vegetables 72 winter moth 52, 52, 264 rootballs 150 wind damage 12 watering cans 53, 53, 57 winter protection see frost rootstocks 153, 153 winter storage 73 watermelon 119, 240, 242, 248 winter storage 73, 73 site and soil 149–50 yields 242 weeds 49–50, 72 wires, training fruit 162, 162, 210 staking 158–59 ventilation annual weeds 50 wireworm 264 types to buy 150 cold frames 45 bed system 33 woolly aphid 264 watering 160, 160 greenhouses 44 cane fruits 218 worm composting 26, 26 see also individual types vermiculite 64, 64 in compost 25 wound paint 165 verticillium wilt 207, 263 crop rotation 31, 82–83 woven mesh covers 48, 48 of fruit viability, seed 61 cucurbit beds 116 woven mesh fences 13, 13 tree onions 94, 240, 247 vine eyes 162 diseases and 51 yardlong beans 95, 100, 238, 242 tree ties 158, 159, 163 vine weevil 52, 250, 263 mechanical control 49–50, 49, 50 yields 242–43 troughs, herb 138 vines see grape vines mulches and 41, 49, 49, 50 zinc 17 trowels 55, 56 violet root rot 263 no-digging system 39 deficiency 17 tube pots 63 viruses 51, 264 perennial weeds 49, 50 zucchini 75, 114, 117 tunnel cloches 46, 47, 47 vectors 263–64 seed 66 in containers 114–15 turbulence, wind 12 walls soft fruits 209 crop planner 239 turf paths 34 fixing wires to 162, 162 soil preparation 38, 39, 49, 49 crop yields 242 turnip gall weevil 263 microclimates 10, 10 tree fruits 161 harvesting 116, 117 turnip tops 74, 88, 240, planting tree fruit against 159 weedkillers 40, 50, 50, 72 problems 117, 247 raised beds 34 whip-and-tongue grafting 154, 155 recommended cultivars 117 242, 248 walnut blotch 264 white blister 264 routine care 117 turnips 74, 82, 83, 88 walnut leaf blight 264 white rot 31, 51 site and soil 117 walnuts 148, 149, 156, 204, white currants 148, 206, 221–22 sowing and planting 62, 114, 117 crop planner 240 243, 249 crop yields 243 crop yields 242 wasps 264 harvesting 222 germination rate 69 water problems 222, 249 harvesting and storing 73, 84, rainfall 11 pruning 210, 221–22 waterlogging 11, 16, 264 recommended cultivars 222 88 whitefly 52, 250, 264 problems 88, 248 recommended cultivars 88 routine care 88 site and soil 82, 88 sowing 65, 68, 69, 83, 88 ACKNOWLEDGMENTS Consultants: Plant Problems Editors Louise Abbott, Alison Copland, DK/Elaine Hewson: 141(Foeniculum; Salvia). Andrew Halstead (pests) Helen Fewster, Candida Frith-Macdonald, Linden GAP Photos: Elke Borkowski 2c. Beatrice Henricot; Chris Prior (diseases) Hawthorne, Jane Simmonds Garden Picture Library: Mayer/Le Scanff 11tl; Editorial assistance Joanna Chisholm; Victoria Mel Watson 205t. Illustrations Karen Gavin, artworks Heyworth-Dunne; Letitia Luff; Simon Maughan; John Glover: 7t, 36bl, 43tc, 46bcr, 46t, 181, Gill Tomblin, garden plans, page 30 Frank Ritter; Diana Vowles; Fiona Wild 196tc, 204t. Designer Alison Donovan Holt Studios International: 45br, 236b; Nigel Index Hilary Bird Design assistance Thomas Keene; Antonio Toma Cattlin 17, 250tr, 250cra, 250cr, 250bc, 250cbl; Managing editor Anna Kruger Inga Spence 206t. PUBLISHER’S ACKNOWLEDGMENTS Managing art editor Lee Griffiths Hozelock Ltd.: 53bl, 54bc. First edition, 2002 DTP design Louise Waller Andrew Lawson: 151. Dorling Kindersley would like to thank all staff at Media resources Romaine Werblow Joy Michaud/Sea Spring Photos: 44b, 75c. the RHS for their time and assistance, in particular: Picture research Samantha Nunn Oxford Scientific Films: Bob Gibbons 185. At Vincent Square, Susanne Mitchell, Barbara Haynes Photolibrary: Lynn Keddie 29clb; Gary K. Smith and Karen Wilson. Revised edition, 2012 35ftr; Juliette Wade 132ftr. At Wisley, Jim Arbury and Jim England for their Picture research Susie Peachey Photos Horticultural: 32bl, 32bc, 41b, 42br, 48bl, invaluable guidance during photography; the DK Images Lucy Claxton; Rose Horridge; 211b, 226t, 235b, 250tl. ever-patient staff in the garden, including Jonathan Romaine Werblow Michael Pollock: 13bc, 13br, 23tl, 39tc, 250bcl, Keyte, Dean Peckett, Anna Stankiewicz-Davies, Proof reader Ella James 250bfr. Alessandra Valsecchi, and Richard White; Paul Harry Smith Collection: 120bl, 177. Alexander and Mike Grant for their expert advice. PHOTOGRAPHIC CREDITS The publisher would like to thank the following for All other images © Dorling Kindersley. Thanks also for the loan of equipment and plants their kind permission to reproduce their photographs: For further information see: to: Defenders Ltd.; S.E. Marshall & Co. Ltd.; Suttons (Key: t=top, b=bottom, r=right, l=left, c=center, www.dkimages.com Seeds; and for horticultural advice to Amanda Denis a=above, f=far) at the Citrus Centre, R. Boskovic, T. Sonneveld, and K.R. Tobutt. Defenders Ltd.: 52b (all). DK/Alan Buckingham: 4b, 98, 141 (Anthriscus; Photographic models Jim Arbury, Paul Atkinson, Satureja), 148 (Mespilus; Morus; Prunus armenica), Murdo Culver, Jim England, Ron Gilkerson, 250 (Psila rosae; bitter pit; magnesium deficiency). Jonathan Keyte, Hannah Reid, Anna Stankiewicz- Davies, Kit Strange, Alessandra Valsecchi