Causal Agent:
Fungus (Oidium sp.)
| Characteristic Symptoms: | |
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Tiny, light yellow spots on leaf surface. |
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White, powdery growth (mycelia & spores) appears on the underside & upper surface of the leaf as the spots enlarge. |
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Fruit infection has not been observed in the Philippines but has been reported in other papaya growing areas. |
| Conditions for Disease Development: | |
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The disease develops quickly under favorable conditions (dense plant growth and low light intensity). |
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High relative humidity is favourable for infection and conidia survival; however infection can occur at RH below 50%. |
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The optimum temperature for disease development is 20-27°C; Under field conditions, the disease stops at high temperatures (38°C and above). |
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The time between infection and symptom appearance is 3-7 days, in which large number of spores/conidia are produced. |
| Management and Control: | |
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Maintain good field sanitation (i.e. remove infected plants/plant parts as soon as symptoms are observed).
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Avoid excessive use of nitrogenous fertilizer.
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Increase light intensity/avoid dense planting or overcrowding. |
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Spray with chemical fungicides like sulfur-based fungicide (e.g. Kumulus®) or thiophanate-methyl (e.g. Tango, Topsin®), azoxystrobin (Amistar®, MiradorⓇ, RobatoⓇ), difenoconazole (e.g. ScoreⓇ, MontanaⓇ, PursueⓇ, BashⓇ) and tebuconazole (e.g. Folicur®). |
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