Didymella bryoniae (gummy stem blight of cucurbits)
Identity
- Preferred Scientific Name
- Didymella bryoniae (Auersw.) Rehm
- Preferred Common Name
- gummy stem blight of cucurbits
- Other Scientific Names
- Stagonosporopsis cucurbitacearum Aveskamp, Gruyter & Verkley
- Ascochyta citrullina (CHESTER) SMITH
- Ascochyta cucumis Fautrey & Roum.
- Ascochyta melonis Potebnja
- Cercospora citrullina Cooke
- Cercospora cucurbitae Ell. & Ev.
- Didymella melonis Pass.
- Didymosphaeria bryoniae (AUERSW.) NIESSL
- Didymosphaeria effusa Sacc.
- Didymosphaeria melonis Pidoplichko
- Mycosphaerella citrullina (C.O.Sm.) Grossenbacher
- Mycosphaerella melonis (Pass.) Chiu & Walker
- Phoma cucurbitacearum (Fr. ex Fr.) Sacc.
- Phyllosticta citrullina Chester
- Sphaerella bryoniae AUERSW.
- Sphaeria bryoniae FUCKEL
- International Common Names
- Englishblack rot of cucumber and pumpkincercospora leafspot of squashearly leaf spot of groundnutleaf spot of cucurbits
- Spanishcaries negra del pepinochamuscado de los tallos del pepino
- Frenchbrulure des tiges du concombre et du melonchancre gommeux des tigestaches foliaires de la pastèque
- Local Common Names
- GermanySchwarzfaeule: GurkengewaechseStengelbrand: Gurkengewaechse
- EPPO code
- CERCCI (Cercospora citrullina)
- EPPO code
- DIDYBR (Didymella bryoniae)
Pictures
- gummy stem blight.jpg)
Didymella bryoniae
Gummy stem blight of pumpkin
CABI
- gummy stem blight2.jpg)
Didymella bryoniae
gummy stem blight of pumpkin leaf, close up
CABI
Didymella bryoniae
Gummy stem blight on pumpkin stem
CABI
Didymella bryoniae
Gummy stem blight on pumpkin stem
CABI
Didymella bryoniae
Blight of watermelon
Benson Ngigi, Kenya
Slide mount
Cucurbit stem rot, D. bryoniae.
©J.M. Waller/CABI BioScience
Distribution
Host Plants and Other Plants Affected
| Host | Host status | References |
|---|---|---|
| Benincasa hispida (wax gourd) | Other | |
| Citrullus lanatus (watermelon) | Main | Boughalleb et al. (2007) Jensen et al. (2011) |
| Cucumis melo (melon) | Main | |
| Cucumis sativus (cucumber) | Main | |
| Cucurbita (pumpkin) | Main | |
| Cucurbita maxima (giant pumpkin) | Main | Jensen et al. (2011) |
| Cucurbita moschata (pumpkin) | Main | Moumni et al. (2019) |
| Cucurbita pepo (marrow) | Main | Iacob et al. (2013) |
| Eusideroxylon zwageri (billian) | Unknown | Adebola et al. (2015) |
| Lagenaria siceraria (bottle gourd) | Other | Mukhtar et al. (2013) |
| Luffa aegyptiaca (loofah) | Unknown | Silva et al. (2013) |
| Momordica charantia (bitter gourd) | Main | Choi et al. (2015) |
| Sechium edule (chayote) | Main | Tsai and Chen (2012) |
| Sicyos angulatus (burcucumber) | Other | Hong et al. (2014) |
Symptoms
Gummy stem blight of cucurbits produces a variety of symptoms which are referred to as leaf spot, stem canker, vine wilt and black fruit rot. Lesions on leaves and fruit usually begin as spreading water-soaked areas; in the former these may have a chlorotic halo, become light brown and irregular in outline; leaves can be destroyed. On fruit, dark cracked sunken lesions form, beneath which an extensive rot is found. In the field the first symptoms may be plant collapse where sunken, girdling cankers lead to total loss. Infection also occurs on seedlings. Spots on stems often elongate into streaks (usually starting at the joints) and have an amber exudate of gummy material. The size and colouring of spots vary according to crop. The main characteristic features are the gummy exudate on stem and fruit lesions, and the abundant pycnidia followed by perithecia. The pycnidia, whether on fruit, stem, or leaf, are closely spaced groups of the dark brown to black fruiting bodies, just large enough to be seen without a hand lens. Sometimes they are arranged in rings on the fruit or leaf surface.
During the rainy season lesions can become water soaked and can spread and lead to severe defoliation. Further development can lead to bark scaling and cracking in cucurbit vines and the collar region of watermelon. Gummy exudates may occur from cracks, especially in watermelon and pumpkin. Severe infection often results in death of the plant (University of Hawaii, 2012).
List of Symptoms/Signs
| Symptom or sign | Life stages | Sign or diagnosis |
|---|---|---|
| Plants/Fruit/gummosis | ||
| Plants/Fruit/lesions: black or brown | ||
| Plants/Fruit/ooze | ||
| Plants/Leaves/abnormal colours | ||
| Plants/Leaves/necrotic areas | ||
| Plants/Leaves/yellowed or dead | ||
| Plants/Stems/gummosis or resinosis | ||
| Plants/Stems/mould growth on lesion | ||
| Plants/Stems/ooze | ||
| Plants/Whole plant/plant dead; dieback | ||
| Plants/Whole plant/wilt |
Prevention and Control
D. bryoniae can survive on seeds, weeds and plant debris from previously infected cucurbit crops. Miller et al. (2001) recommend using only disease-free seed produced in arid locations. Seeds from healthy fruits are free of the disease but D. bryoniae-infected seeds may symptomless, and seed treatment may be necessary if not previously treated. Seedlings should be inspected regularly for signs of infection as the disease is common at this stage.
Weeds are a source of inoculum and should be eradicated from the field before planting cucurbit crops. Crop refuse should be ploughed deeply immediately after harvest to reduce fungus survival. Crop rotation with non-cucurbit crops, so that cucurbits are grown only every 3-4 years, is also recommended, as are routine applications of foliar-protectant fungicides (Miller et al., 2001). Fungicides should be used prevetatively, with applications starting at the early stages of plant growth if weather conditions are conducive to the development of the disease. Avoid wounding the fruits at harvest and store the harvested fruit at 7-10°C to prevent postharvest black rot. Resistant cultivars are currently not available.
Bacillus subtilis is available for use as a biological control agent against D. bryoniae, but its success is dependent on environmental conditions at the time of application.
Impact
Gummy stem blight, caused by Didymella bryoniae, is one of the most important diseases of cucurbits in many countries of the world (Lee et al., 1984).
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Copyright © CABI. CABI is a registered EU trademark. This article is published under a Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0)
History
Published online: 18 December 2021
Language
English
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