Causal Agent:
Fungus (Podosphaera xanthii holomorph Oidium)
| Characteristic Symptoms: | |
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Whitish, powdery fungal growth develops on both leaf surfaces and on petioles, and stems. |
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Infected leaves usually wither and die causing premature senescence of melon plants. |
| Conditions for Disease Development | |
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Disease emergence is favored by dry weather and high relative humidity. |
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Favorable conditions include dense plant growth and low light intensity.
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The primary source of inoculum is the airborne conidia which are dispersed over long distances. |
| Management and Control: | |
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Use of resistant varieties, if available.
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Maintain good field sanitation (e.g. remove & burn plants/plant parts as soon as symptoms are observed). |
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Follow proper plant spacing.
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Avoid too much application of nitrogenous fertilizer. |
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Apply fungicides such as thiophanate methyl (e.g. Tango®, Topsin®), azoxystrobin (Amistar®, MiradorⓇ, RobatoⓇ), difenoconazole (e.g. ScoreⓇ, MontanaⓇ, PursueⓇ, BashⓇ), tebuconazole (e.g. Folicur®) or sulfur-based fungicide (e.g. Kumulus®), or thiophanate-methyl (e.g. Tango, Topsin®), cartap hydrochloride (e.g. PadanⓇ, Barena 50 SP, Gemtrak®), acetamiprid (e.g. MospilanⓇ), acephate (e.g. AcetamⓇ, CompeteⓇ), chlorphenapyr (e.g. Kotetsu) or penthoate (e.g. PennantⓇ, VidexⓇ). |
References:
http://vegetablemdonline.ppath.cornell.edu/factsheets/Cucurbits_PM.htm
Compendium of Cucurbit Diseases (2010) by The American Phytopathological Society
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