Rate Of Appressorium Formation Research Articles

Influence of microclimate on Drechslera leaf spot of young coconuts: effect of desiccation on spore survival and of moisture and shade on infection and disease development

SUMMARYCulture‐produced conidia of Drechslera incurvata from coconut failed to germinate on the leaves of coconut seedlings incubating under the dry conditions of a greenhouse. Viability and rate of appressorium formation of artificially‐dispersed, culture‐produced conidia fell significantly during extended incubation of inoculated seedlings in the greenhouse, when 43% of conidia germinated after 90 days incubation compared with 62% at 59 days and 90% at 24 days. Field‐produced conidia on excised leaves also lost viability upon storage in situ on the laboratory bench; germination fell from 60% at 3 months storage to 0×5% at 5 months and no germination at 6 months.Shading of seedlings in the field with saran cloth producing 30% shade or 50% shade depressed the amount of dew forming on leaves of young coconuts and significantly reduced both the number of infections from artificial inoculations and the severity of leaf spot disease developing subsequently.