Rhizopus head rot, caused by the fungus Rhizopus oryzae, is a potentially destructive disease of sunflowers, although its occurrence is sporadic. It can affect sunflowers grown for both oilseed and confectionery purposes.
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Type of Infestation: Fungal Disease
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Common Name: Rhizopus head rot
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Causal Organism: Rhizopus sp
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Affected Parts Of the plant: Flower Head, Seed and Stalk
Environmental favorable factors for pests/Diseases:
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Temperature & Humidity: High temperatures (above 25°C) and high relative humidity (above 80%) favor infection and disease development. This is because these conditions create a moist environment that allows the fungal spores to germinate and grow easily.
Symptoms of Pest/Disease:
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Initial: Look for brown, irregular, water-soaked spots on the back of the ripening head, usually near the flower stalk.
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Progression: These spots enlarge and become soft and pulpy, covered by a white, superficial mycelium that later turns black.
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Later stages: The infected head may dry prematurely, shrivel, and appear shredded. You might also observe coarse, thread-like mycelial strands within the shredded tissues.
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Spores: Small, black dots (sporangia) appear on the affected head, filled with spores that can be easily released and spread by wind to infect other plants.
Measures to control Pests/Diseases:
| Products |
Technical Names |
Dosages |
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SULVET
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Sulphur 80 % wdg |
750 to 1000 grams per acre |
