A Model Based on Temperature and Leaf Wetness Duration for Establishment of Alternaria Leaf Blight of Muskmelon

We inoculated muskmelon leaves with a conidial suspension of Alternaria cucumerina and subjected the leaves to various controlled environments to determine the influence of temperature and leaf wetness duration on disease establishment. Disease severity, as measured by a «number of lesion area equivalents» method, increased with increasing wetness dur- ation (2-24 h) at all temperatures tested (12-30 C). The optimum temperature was 18 C, and at least 8 h of leaf wetness were required for significant disease establishment at temperatures of 15-21 C (...)