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Powdery mildew plant Stock Photos and Images
RF2H5DBWK–A very dangerous grape disease that affects the aerial parts of the plant, covering the upper side of the leaves with a white coating. Dark spots appear on diseased leaves. Spots appear turn brown
RMRCDKKN–. Diseases of glasshouse plants. Greenhouse plants; Plant diseases. Fig. 25. Powdery mildew of the cucumber.. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original work.. Bewley, W. F. (William Fleming). London, E. Benn
RF2HW6G80–Mass of Botrytis cinerea spores on an infected snap bean pod. Fungal disease - Grey mould.
RF2H4W25E–A very dangerous grape disease that affects the aerial parts of the plant, covering the upper side of the leaves with a white coating. Dark spots appear on diseased leaves. Spots appear turn brown
RME9CMGR–Powdery mildew, Erysiphe euonymicola, white spotting on the leaves of a Euonymus foliage garden shrub in Ravello, Italy
RMRCDKM0–. Diseases of glasshouse plants. Greenhouse plants; Plant diseases. Fig. 25. Powdery mildew of the cucumber.. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original work.. Bewley, W. F. (William Fleming). London, E. Benn
RF2HW6G7N–Mass of Botrytis cinerea spores on an infected snap bean pod. Fungal disease - Grey mould.
RF2H5PDA3–A very dangerous grape disease that affects the aerial parts of the plant, covering the upper side of the leaves with a white coating. Dark spots appear on diseased leaves. Spots appear turn brown
RME9CMGM–Powdery mildew, Erysiphe euonymicola, white spotting on the leaves of a Euonymus foliage garden shrub in Ravello, Italy
RMRCDPRT–. Diseases of economic plants. Plant diseases. 118 Diseases of Economic Plants of the gooseberry. It has quite prohibited the cultivation of the finer sorts of EngHsh gooseberries in America and is a grave menace to the culture of gooseberries in Europe. Its destructiveness is due not alone to injury to the foliage, bush, and to the fruit yield, but also to lack in. Fig. 59. — Stages at which spraying should be given for mildew. After Close. salabihty, owing to the unsighthness of the partially diseased fruits. This powdery-mildew has been very successfully combated by use of potassium sulfid,
RF2HW6GA8–Mass of Botrytis cinerea spores on an infected snap bean pod. Fungal disease - Grey mould.
RF2H43M3D–A very dangerous grape disease that affects the aerial parts of the plant, covering the upper side of the leaves with a white coating. Dark spots appear on diseased leaves. Spots appear turn brown
RMAPG2YY–Powdery mildew Blumeria graminis f.sp. hrdei brown rust Puccinia hordei infection on seedling barley leaf
RMRCC6KB–. Diseases of economic plants. Plant diseases. 118 Diseases of Economic Plants of the gooseberry. It has quite prohibited the cultivation of the finer sorts of Enghsh gooseberries in America and is a grave menace to the culture of gooseberries in Europe. Its destructiveness is due not alone to injury to the fohage, bush, and to the fruit yield, but also to lack in. Fig. 59. — Stages at which spraying should be given for mildew. After Close. salability, owing to the unsightliness of the partially diseased fruits. This powdery-mildew has been very successfully combated by use of potassium sulfid
RF2HW6G7F–Mass of Botrytis cinerea spores on an infected snap bean pod. Fungal disease - Grey mould.
RF2H64JK1–A very dangerous grape disease that affects the aerial parts of the plant, covering the upper side of the leaves with a white coating. Dark spots appear on diseased leaves. Spots appear turn brown
RMAT9N8P–Powdery mildew Leveillula taurica infected tomato crop with damage on upper and lower surfaces
RMRCC6AX–. Diseases of economic plants. Plant diseases. Fig. 179. â Cowpea leaflet spotted with powdery-mildew. Original. Fig. 180. ââ Leaflet of cowpea showing Cercospora spots. Original.. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original work.. Stevens, Frank Lincoln, 1871-1934; Hall, John Galentine, 1870-. New York, Macmillan
RMT1MG75–Powdery mildew (Blumeria graminis f.sp. hordei) photomicrograph of a fungal disease pustule, with mycelium and hyphae on a barley leaf
![. Diseases of economic plants. Plant diseases. Fig. 179. — Cowpea leaflet spotted Fig. 180. — Leaflet of cowpea showing with powdery-mildew. Original. Carcospora spots. Original.. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original work.. Stevens, Frank Lincoln, 1871- [from old catalog]; Hall, John Galentine, 1870- [from old catalog] joint author. New York, The Macmillan company Stock Photo](https://c8.alamy.com/comp/RCDPDB/diseases-of-economic-plants-plant-diseases-fig-179-cowpea-leaflet-spotted-fig-180-leaflet-of-cowpea-showing-with-powdery-mildew-original-carcospora-spots-original-please-note-that-these-images-are-extracted-from-scanned-page-images-that-may-have-been-digitally-enhanced-for-readability-coloration-and-appearance-of-these-illustrations-may-not-perfectly-resemble-the-original-work-stevens-frank-lincoln-1871-from-old-catalog-hall-john-galentine-1870-from-old-catalog-joint-author-new-york-the-macmillan-company-RCDPDB.jpg ". Diseases of economic plants. Plant diseases. Fig. 179. — Cowpea leaflet spotted Fig. 180. — Leaflet of cowpea showing with powdery-mildew. Original. Carcospora spots. Original.. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original work.. Stevens, Frank Lincoln, 1871- [from old catalog]; Hall, John Galentine, 1870- [from old catalog] joint author. New York, The Macmillan company Stock Photo")
RMRCDPDB–. Diseases of economic plants. Plant diseases. Fig. 179. — Cowpea leaflet spotted Fig. 180. — Leaflet of cowpea showing with powdery-mildew. Original. Carcospora spots. Original.. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original work.. Stevens, Frank Lincoln, 1871- [from old catalog]; Hall, John Galentine, 1870- [from old catalog] joint author. New York, The Macmillan company
RF2HH9APA–Soybean root infected by a disease that causes the entire plant to shrivel and yield losses.
RM2A49DBW–Powdery mildew (Erysiphe graminis f.sp. tritici) infection on wheat crop coming into ear, white pustules on the stem and lower leaves
RMRCC6GN–. Diseases of economic plants. Plant diseases. VEGETABLE AND FIELD CROPH 221 Powdery mildew (Erysiphe polijgoni DC.)- —This mildew of the cucumber and cantaloupe in general appearance resembles that described for the grape. It is more com- mon under glass than in the open, and here indicates too much moisture and too little ven- tilation. It is sel- dom injurious in the field. Flowers of sul- phur applied to the hot water or steam pipes in the form of a paste is useful. Leaf blight, cer- cosporose {Cercos- pora CucurbitcB Ell. &Ev.). —The spots of this disease are much like those of altern
RF2HA76FK–Barley yellow dwarf (BYD) is a plant disease caused by the barley yellow dwarf virus (BYDV). Symptoms - red leaves on wheat.
RMD98E1E–White covering of powdery mildew, Erysiphe galeopsidis, on a garden weed red deadnettle, Lamium purpureum, leaves
RMRCC6HE–. Diseases of economic plants. Plant diseases. 206 DISEASES OF ECONOMIC PLANTS is destructive upon the lima bean, producing upon pods and leaves large, brown patches, with the pycnidia ar- ranged in concentric circles. When the disease is very prevalent, the pods fail to V mature their seeds. Spraying with Bordeaux mixture is recommended. Powdery mildew {Ery- siphe polygoni DC). — The characters of the powdery mildews as described for the grape apply here suffi- ciently to serve for recog- nition purposes. This dis- ease is not usually serious, and is amenable to treat- ment with flowers of su
RF2HA76G0–Barley yellow dwarf (BYD) is a plant disease caused by the barley yellow dwarf virus (BYDV). Symptoms - red leaves on wheat.
RM2DRXHJ6–Powdery mildew (Erysiphe graminis) mycelium and cleistothecia and brown leaf rust (Puccinia triticina) pustules on a wheat leaf
![. Diseases of fruits and nuts. Fruit; Nuts. Fig. 9.—Powdery mildew of apple on stems of twigs. apple, injure the leaves, and cause deformity of the fruit. These rusts have the peculiarity of also affecting another entirely different kind of plant, on which they produce a different form of rust. This is similar to the connection between wheat rust and the barberry bush or white pine blister rust and the wild currant. In the case of the apple rusts, the second (alternate) hosts are species of cedar and juniper on whieli are formed woody, or sometimes gelatinous, galls, or ''cedar apples.". Stock Photo](https://c8.alamy.com/comp/RCDNX4/diseases-of-fruits-and-nuts-fruit-nuts-fig-9powdery-mildew-of-apple-on-stems-of-twigs-apple-injure-the-leaves-and-cause-deformity-of-the-fruit-these-rusts-have-the-peculiarity-of-also-affecting-another-entirely-different-kind-of-plant-on-which-they-produce-a-different-form-of-rust-this-is-similar-to-the-connection-between-wheat-rust-and-the-barberry-bush-or-white-pine-blister-rust-and-the-wild-currant-in-the-case-of-the-apple-rusts-the-second-alternate-hosts-are-species-of-cedar-and-juniper-on-whieli-are-formed-woody-or-sometimes-gelatinous-galls-or-cedar-applesquot-RCDNX4.jpg ". Diseases of fruits and nuts. Fruit; Nuts. Fig. 9.—Powdery mildew of apple on stems of twigs. apple, injure the leaves, and cause deformity of the fruit. These rusts have the peculiarity of also affecting another entirely different kind of plant, on which they produce a different form of rust. This is similar to the connection between wheat rust and the barberry bush or white pine blister rust and the wild currant. In the case of the apple rusts, the second (alternate) hosts are species of cedar and juniper on whieli are formed woody, or sometimes gelatinous, galls, or ''cedar apples.". Stock Photo")
RMRCDNX4–. Diseases of fruits and nuts. Fruit; Nuts. Fig. 9.—Powdery mildew of apple on stems of twigs. apple, injure the leaves, and cause deformity of the fruit. These rusts have the peculiarity of also affecting another entirely different kind of plant, on which they produce a different form of rust. This is similar to the connection between wheat rust and the barberry bush or white pine blister rust and the wild currant. In the case of the apple rusts, the second (alternate) hosts are species of cedar and juniper on whieli are formed woody, or sometimes gelatinous, galls, or ''cedar apples.".
RF2HA76JC–Barley yellow dwarf (BYD) is a plant disease caused by the barley yellow dwarf virus (BYDV). Symptoms - red leaves on wheat.
RM2E1E22R–Single Rosa ‘the Brownie Rose’ floribunda bud against an out of focus natural background, natural floral portrait
RM2D8148K–Cucumber powedery mildew (Podosphaera fuliginea) white fungal mycelium on leaves of a fruiting cucurbit plant, Berkshire, September
RMRCDPJN–. Diseases of economic plants. Plant diseases. is destructive upon the lima bean, producing upon pods and leaves large, brown patches, with the pycnidia ar^ ranged in concentric circles. When the disease is very prevalent, the pods fail to mature their seeds. Spraying with Bordeaux mixture is recommended. Powdery mildew (Ery- siphe polygoni DC). — The characters of the powdery mildews as described for the grape apply here suffi- ciently to serve for recog- nition purposes. This dis- ease is not usually serious, and is amenable to treat- , ment with flowers of sul- phur or spraying with liver o
RF2HA76FW–Barley yellow dwarf (BYD) is a plant disease caused by the barley yellow dwarf virus (BYDV). Symptoms - red leaves on wheat.
RM2E1E207–Single Rosa ‘the Brownie Rose’ floribunda bud against an out of focus natural background, natural floral portrait
RM2D81496–Cucumber powedery mildew (Podosphaera fuliginea) white fungal mycelium on leaves of a fruiting cucurbit plant, Berkshire, September
RMRCDPHW–. Diseases of economic plants. Plant diseases. VEGETABLE AND FIELD CROPS 221 Powdery mildew (Erysiphe polygoni DC).— This mildew of the cucumber and cantaloupe in general appearance resembles that described for the grape. It is more com- mon under glass than in the open, and here indicates too much moisture and too little ven- tilation. It is sel- dom injurious in the field. Flowers of sul- phur applied to the hot water or steam pipes in the form of a paste is useful. Leaf blight, cer- cosporose (Cercos- pora Cucurbitce Ell. &Ev.). — The spots of this disease are much like those of alterna
RF2HA76G4–Barley yellow dwarf (BYD) is a plant disease caused by the barley yellow dwarf virus (BYDV). Symptoms - red leaves on wheat.
RM2E1E20H–Single Rosa ‘the Brownie Rose’ floribunda bud against an out of focus natural background, natural floral portrait
RM2D8148W–Cucumber powedery mildew (Podosphaera fuliginea) white fungal mycelium on leaves of a fruiting cucurbit plant, Berkshire, September
![. Diseases of economic plants. Plant diseases. TREES AND TIMBER 439 vated perithecia, the cluster surrounded by a border of dead tissue. Premature defoliation results. The disease is very abundant in all parts of the United States. In- fected materials should be burned in the fall. Powdery mildew, uncinulose. See oak. Powdery mildew, phyliactinose. See oak, FILBERT. See hazel. FIR Rust (Aecidium elatinum All). & Schw.). — This cluster-cup fungus has been noted in Minnesota."^ It produces bushy distortions, 'Svitches' brooms," by causing profuse branch- ing of the affected part of Stock Photo](https://c8.alamy.com/comp/RCC6AE/diseases-of-economic-plants-plant-diseases-trees-and-timber-439-vated-perithecia-the-cluster-surrounded-by-a-border-of-dead-tissue-premature-defoliation-results-the-disease-is-very-abundant-in-all-parts-of-the-united-states-in-fected-materials-should-be-burned-in-the-fall-powdery-mildew-uncinulose-see-oak-powdery-mildew-phyliactinose-see-oak-filbert-see-hazel-fir-rust-aecidium-elatinum-all-amp-schw-this-cluster-cup-fungus-has-been-noted-in-minnesotaquot-it-produces-bushy-distortions-svitches-broomsquot-by-causing-profuse-branch-ing-of-the-affected-part-of-RCC6AE.jpg ". Diseases of economic plants. Plant diseases. TREES AND TIMBER 439 vated perithecia, the cluster surrounded by a border of dead tissue. Premature defoliation results. The disease is very abundant in all parts of the United States. In- fected materials should be burned in the fall. Powdery mildew, uncinulose. See oak. Powdery mildew, phyliactinose. See oak, FILBERT. See hazel. FIR Rust (Aecidium elatinum All). & Schw.). — This cluster-cup fungus has been noted in Minnesota."^ It produces bushy distortions, 'Svitches' brooms," by causing profuse branch- ing of the affected part of Stock Photo")
RMRCC6AE–. Diseases of economic plants. Plant diseases. TREES AND TIMBER 439 vated perithecia, the cluster surrounded by a border of dead tissue. Premature defoliation results. The disease is very abundant in all parts of the United States. In- fected materials should be burned in the fall. Powdery mildew, uncinulose. See oak. Powdery mildew, phyliactinose. See oak, FILBERT. See hazel. FIR Rust (Aecidium elatinum All). & Schw.). — This cluster-cup fungus has been noted in Minnesota."^ It produces bushy distortions, 'Svitches' brooms," by causing profuse branch- ing of the affected part of
RF2HA76FP–Barley yellow dwarf (BYD) is a plant disease caused by the barley yellow dwarf virus (BYDV). Symptoms - red leaves on wheat.
RM2E1E208–Single Rosa ‘the Brownie Rose’ floribunda bud against an out of focus natural background, natural floral portrait
RMRCDPJR–. Diseases of economic plants. Plant diseases. 206 DISEASES OF ECONOMIC PLANTS. is destructive upon the lima bean, producing upon pods and leaves large, brown patches, with the pycnidia ar^ ranged in concentric circles. When the disease is very prevalent, the pods fail to mature their seeds. Spraying with Bordeaux mixture is recommended. Powdery mildew (Ery- siphe polygoni DC). — The characters of the powdery mildews as described for the grape apply here suffi- ciently to serve for recog- nition purposes. This dis- ease is not usually serious, and is amenable to treat- , ment with flowers of s
RF2HA76EP–Barley yellow dwarf (BYD) is a plant disease caused by the barley yellow dwarf virus (BYDV). Symptoms - red leaves on wheat.
RM2E1E25P–Single Rosa ‘the Brownie Rose’ floribunda bud against an out of focus natural background, natural floral portrait
RMF0921D–Early development of powedery mildew on the flower of a purple flowering clematis in summer, Berkshire, August
RMRCDPAF–. Diseases of economic plants. Plant diseases. TBEES AND TIMBER 449 causes a stoppage of the water supply to the more distant portions of the leaf, resulting in dead areas. Dead twigs should be pruned out, and infected material col- lected and burned. Spraying with Bordeaux mixture may be practiced if the expense is warranted. Powdery mildew. See oak. BLACK WALNUT Anthracnose, Gnomoniose (Marsonia juglandis (Lib.) Sacc. of Gnomonia juglandis). — Conspicuous brown spots, 2-4 mm. in diameter, appear upon the leaflets, which soon yellow and fall. Upon the lower sides of the leaf spots are small,
RF2HA8922–Barley yellow dwarf (BYD) is a plant disease caused by the barley yellow dwarf virus (BYDV) and is the most widely distributed viral disease of cereal
RM2E1E20A–Single Rosa ‘the Brownie Rose’ floribunda bud against an out of focus natural background, natural floral portrait
RMRCC6A0–. Diseases of economic plants. Plant diseases. OBNAMENTAL PLANTS 463 Ascochytose, ray blight (Ascochyta chrysanthemi Stevens). — In this disease, described by Stevens ^ as doing consider- able damage in North Caro- lina, the ray flowers are bUghted, resulting in im- perfect opening of the buds. Thorough spraying with Bordeaux mixture from the beginning of the season un- til blossoming, accompanied by destruction of infected refuse, has proved a satis- factory treatment. Powdery mildew {Oidium chrysanthemi Rbh. of Ery- siphe cichoracearum DC). — This mildew occurs as white, flour-like spots upo
RF2HA893X–Barley yellow dwarf (BYD) is a plant disease caused by the barley yellow dwarf virus (BYDV) and is the most widely distributed viral disease of cereal
RM2E1E296–Single Rosa ‘the Brownie Rose’ floribunda bud against an out of focus natural background, natural floral portrait
RMC7514X–Brown rust (Puccinia hordei) early infection on seedling barley leaf with some powdery mildew
RMRCDPD6–. Diseases of economic plants. Plant diseases. CEREALS 375 Anthracnose (Colletotrichum cereale Manns). — This an- thracnose seems to prevail on wheat as extensively as upon rye. Upon wheat the head or parts of it are not destroyed, as in the case of rye, but general weakness of the plant and light shriveled grain follows the attack. Powdery mildew (Erysiphe graminis DC). — The usual characters of the powdery mildews are exhibited: a whitish,. Fig. 160. — Normal wheat kernels and shriveled kernels due to anthracnose. After Manns. flour-like coating in irregular circular spots upon the leaves an
RF2HA893T–Barley yellow dwarf (BYD) is a plant disease caused by the barley yellow dwarf virus (BYDV) and is the most widely distributed viral disease of cereal
RMRCC6K2–. Diseases of economic plants. Plant diseases. Small Fruits 123 Oregon, and California, it is regarded as the most important grape disease. Powdery-mildew attacks all parts of the plant except the roots, showing first upon both the upper and lower surface of young leaves as whitish circular spots, which ap- pear somewhat as though dusted with flour. These spots enlarge, coalesce, and may cover the whole leaf. The af- fected leaf is retarded in growth and becomes distorted. Mildewed blossoms fail to set their fruit, and fruit that. Fig. 62. — Black-rot as it shows on the leaves. After Anderson.
RF2RD8HJH–Cucumber leaves affected by downy mildew close-up. Cucumber disease Peronosporosis or False powdery mildew. Leaf with yellow spots.
![. Diseases of economic plants. Plant diseases. TREES AND TIMBER 439 vated perithecia, the cluster surrounded by a border of dead tissue. Premature defoliation results. The disease is very abundant in all parts of the United States. In- fected materials should be burned in the fall. Powdery mildew, uncinulose. See oak. Powdery mildew, phyllactinose. See oak. FILBERT. See hazel. FIR Rust (Aecidium elatinum Alb. & Schw.). — This cluster-cup fungus has been noted in Minnesota.1 It produces bushy distortions, "witches' brooms," by causing profuse branch- ing of the affected part of th Stock Photo](https://c8.alamy.com/comp/RCDPAN/diseases-of-economic-plants-plant-diseases-trees-and-timber-439-vated-perithecia-the-cluster-surrounded-by-a-border-of-dead-tissue-premature-defoliation-results-the-disease-is-very-abundant-in-all-parts-of-the-united-states-in-fected-materials-should-be-burned-in-the-fall-powdery-mildew-uncinulose-see-oak-powdery-mildew-phyllactinose-see-oak-filbert-see-hazel-fir-rust-aecidium-elatinum-alb-amp-schw-this-cluster-cup-fungus-has-been-noted-in-minnesota1-it-produces-bushy-distortions-quotwitches-broomsquot-by-causing-profuse-branch-ing-of-the-affected-part-of-th-RCDPAN.jpg ". Diseases of economic plants. Plant diseases. TREES AND TIMBER 439 vated perithecia, the cluster surrounded by a border of dead tissue. Premature defoliation results. The disease is very abundant in all parts of the United States. In- fected materials should be burned in the fall. Powdery mildew, uncinulose. See oak. Powdery mildew, phyllactinose. See oak. FILBERT. See hazel. FIR Rust (Aecidium elatinum Alb. & Schw.). — This cluster-cup fungus has been noted in Minnesota.1 It produces bushy distortions, "witches' brooms," by causing profuse branch- ing of the affected part of th Stock Photo")
RMRCDPAN–. Diseases of economic plants. Plant diseases. TREES AND TIMBER 439 vated perithecia, the cluster surrounded by a border of dead tissue. Premature defoliation results. The disease is very abundant in all parts of the United States. In- fected materials should be burned in the fall. Powdery mildew, uncinulose. See oak. Powdery mildew, phyllactinose. See oak. FILBERT. See hazel. FIR Rust (Aecidium elatinum Alb. & Schw.). — This cluster-cup fungus has been noted in Minnesota.1 It produces bushy distortions, "witches' brooms," by causing profuse branch- ing of the affected part of th
RF2T5PJE1–Rust and powdery mildew on sunflower leaf visible under magnification. A fungal disease of sunflowers caused by Puccinia helianthi (rust) and Golovino
RMRCDP4T–. Diseases of flowers and other ornamentals. Flowers; Plant diseases. 74 California Agricultural Extension Service [Cir. 118 Powdery Mildew.—In affected trees the terminal leaves are covered with a felty white fungus growth, Microsphaera alni, and somewhat de- formed. This is most common in wet spring weather. a A'iMM.. :•. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original work.. Smith, Ralph E. (Ralph Eliot), 1874-1953. Berkeley, C
RF2T5PJDX–Rust and powdery mildew on sunflower leaf visible under magnification. A fungal disease of sunflowers caused by Puccinia helianthi (rust) and Golovino
RMRCDKJG–. Diseases of glasshouse plants. Greenhouse plants; Plant diseases. DISEASES DUE TO FUNGI 109 soon die and hang down the stem. Tiny heaps of spores are produced on the diseased areas on both sides of the leaf. Control is a difficult matter, and infected plants should be destroyed immediately. Spraying with a copper fungicide is recommended as a means of protecting the healthy plants. Powdery Mildew of the Chrysanthemum.—Chrysan- themums grown under glass frequently suffer from this disease, due to Oidium chrysanthemi Robh. The leaves become covered with a white, powdery, fungal growth. The pre
RMRCCK6J–. Diseases of wheat, oats, barley, and rye. Grain. BOEWE: DISEASES OF WHEAT, OATS, BARLEY, AND RYE 41 conditions ideal for infection. The damage the disease does to the wheat plant is due to the fact that the fungus robs the leaves of food manufactured for the plant's own use as well as to the fact that attack by the fungus reduces the amount of. Fig. 11.—Powdery mildew on wheat. The fungus may first be seen on the upper surface of a leaf as small, irregular or circular, grayish-white spots. These spots enlarge and become floury in appearance; they may cover the greater part of the leaf. As th
RMAJTDHE–Powdery mildew (Blumeria graminis f.sp. hordei) disease pustules on young barley plant leaf
RMRCDPA9–. Diseases of economic plants. Plant diseases. ORNAMENTAL PLANTS 463 Ascochytose, ray blight (Ascochyta chrysanthemi Stevens). — In this disease, described by Stevens1 as doing consider- able damage in North Caro- lina, the ray flowers are blighted, resulting in im- perfect opening of the buds. Thorough spraying with Bordeaux mixture from the beginning of the season un- til blossoming, accompanied by destruction of infected refuse, has proved a satis- factory treatment. Powdery mildew (Oidium chrysanthemi Rbh. of Ery- siphe cichoracearum DC). — This mildew occurs as white, flour-like spots upo
RMRCC6D5–. Diseases of economic plants. Plant diseases. CEREALS 375 Anthracnose {Colletotrichum cereale Manns). — This an- thracnose seems to prevail on wheat as extensively as upon rye. Upon wheat the head or parts of it are not destroyed, as in the case of rye, but general weakness of the plant and light shriveled grain follows the attack. Powdery mildew {Erysiphe graminis DC). — The usual characters of the powdery mildews are exhibited: a whitish,. Fig. 160. — Normal wheat kernels and shriveled kernels due to anthracnose. After Manns. flour-like coating in irregular circular spots upon the leaves an
RMRCDKJD–. Diseases of glasshouse plants. Greenhouse plants; Plant diseases. 110 DISEASES OF GLASSHOUSE PLANTS Downy Mildew of the Rose.—This disease, while common on glasshouse roses, is somewhat difficult to detect. Frequently young plants appear to lack vigour for no obvious reason, but a careful examination of the leaves reveals the presence of minute fungal filaments. The causal organism, Peronospora sparsa Berk., is capable. Fig. 31. Powdery mildew of the rose : («) Diseased leaves, (6) summer spores, (c) a perithecium, (d) ascus containing eight ascosporcs. of attackmg all leaves and young shoot
RMRCDP8J–. Diseases of field crops. Plant diseases. 24 California Agricultural Extension Service [Cir. 121 of this type. Resistant varieties of different types of beans may in time be developed but none are available at present. Mosaic.—The leaves of plants attacked by this virus disease are much. Fig. 16.—Powdery mildew of beans. (From Ext. Cir. 119.) puckered and cupped downward at the edges. In color they are darker green than normal or mottled with green and yellow patches (fi<r. 15). Early-affected plants bear little seed. The infection is carried in the seed and spread by aphids.. Please note
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