Stem blight, also known as gummy stem blight, is a major disease of cucurbits, which include plants like watermelon, rockmelon, honeydew, squash, pumpkin, and cucumber. It is caused by a complex of three fungal pathogens: Didymella Bryoniae, Stagonosporopsis citrulli, and Stagonosporopsis caricae. These fungi can cause significant yield losses.
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Type of Infestation: Disease
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Common Name: Stem Blight
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Causal Organism: Didymella Bryoniae
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Affected Parts Of the plant: Stem
Environmental favorable factors for pests/Diseases:
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Temperature: The optimal temperature range for fungal growth lies between 20-30°C (68-86°F). However, infection can occur between 15-35°C (59-95°F). Warmer temperatures can accelerate disease progression.
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Humidity: High humidity (>80%) promotes spore germination, dispersal, and infection. Rainfall, sprinkler irrigation, and condensation on leaves create favorable conditions.
Symptoms of Pest/Disease:
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Leaves: Small, water-soaked lesions that enlarge and turn brown or yellow. The lesions may be surrounded by a yellow halo and may tear and drop out, giving the leaves a ragged appearance.
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Stems: Water-soaked lesions that turn brown or tan. The lesions may become sunken and cracked, and may ooze a reddish-brown or black gummy exudate. In severe cases, the stems may be girdled and killed.
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Fruits: Water-soaked spots that enlarge and turn brown or black. The spots may become greasy and may ooze a gummy exudate. Black fruiting bodies of the fungus may be visible on the fruit.
Measures to control Pests/Diseases:
| Products |
Technical Names |
Dosages |
| KTM |
Thiophanate Methyl 70% WP |
250-600 grams per acre |
| COC50 |
Copper oxychloride 50 % wp |
2gm/ltr |
| K ZEB |
Mancozeb 75% WP |
500gm per Acre |
| META MANCO |
Metalaxyl 8 % + Mancozeb 64 % wp |
1.5 to 2 kg per ha |
