VIEW ARTICLE

Ecology and Epidemiology

Effects of Interrupted Wet Periods on Infection of Sour Cherry by Coccomyces hiemalis. S. P. Eisensmith, Graduate research assistant, Department of Botany and Plant Pathology and the Pesticide Research Center, Michigan State University, East Lansing 48824; A. L. Jones(2), and C. E. Cress(3). (2)Professor, Department of Botany and Plant Pathology and the Pesticide Research Center, Michigan State University, East Lansing 48824; (3)Professor, Department of Crop and Soil Sciences, Michigan State University, East Lansing 48824. Phytopathology 72:680-682. Accepted for publication 17 September 1981. Copyright 1982 The American Phytopathological Society. DOI: 10.1094/Phyto-72-680.

Montmorency sour cherry trees inoculated with conidia of Coccomyces hiemalis were subjected to interrupted wet periods (IWP) and continuous wet periods (CWP) of various durations to determine the effect of dry interruptions on infection by the leaf spot fungus. Fewer lesions per square centimeter of leaf resulted from IWP than from CWP in each of four series of experiments. A trend of decreasing infection with increasing length of dry interruption was observed when initial and final wet periods were 4 and 8 hr. Infection from IWP with an initial 4-hr wet period, 1- to 48-hr dry interruptions, and a final 8-hr wet period was greater than from a 4-hr CWP, but not statistically different from an 8-hr CWP. When the dry period was 108 hr, infection was greater than from a 4-hr CWP, but less than from an 8-hr CWP. Trees allowed to dry up to 16 hr after inoculation developed less infection than trees subjected to wetting immediately after inoculation. Infection on trees given initial wet periods of less than 12 hr was less than on trees with longer initial wet periods.