VIEW ARTICLE

Ecology and Epidemiology

Influence of Temperature and Wetness Duration on Infection of Immature Strawberry Fruit by Phytophthora cactorum. G. G. Grove, Graduate research associate, Department of Plant Pathology, Ohio State University, Ohio Agricultural Research and Development Center, Wooster 44691; L. V. Madden(2), M. A. Ellis(3), and A. F. Schmitthenner(4). (2)(3)(4)Assistant professor, associate professor, and professor, respectively, Department of Plant Pathology, Ohio State University, Ohio Agricultural Research and Development Center, Wooster 44691. Phytopathology 75:165-169. Accepted for publication 1 September 1984. Copyright 1985 The American Phytopathological Society. DOI: 10.1094/Phyto-75-165.

Strawberry fruits (cultivar Midway) inoculated with a sporangial suspension (400/ml) of Phytophthora cactorum were used to determine the effects of wetness duration and temperature on infection level. Infection increased with increased wetness duration (0- 5 hr) at all temperatures tested (6- 30 C). For each wetness duration, infection increased up to the optimum temperature (21 C) and then declined. At temperatures between 17 and 25 C, >1 hr of wetness resulted in >80% infection. A multiple-regression, logistic model accurately described infection as a function of wetness duration and temperature. The model was validated under natural field conditions.