VIEW ARTICLE

Ecology and Epidemiology

Effects of Solar Radiation and Temperature on Fusarium Wilt in Carnation. Y. Ben- Yephet,Department of Plant Pathology, Agriculture Research Organization, The Volcani Center, P.O. Box 6, Bet Dagan 50250, Israel; D. Shtienberg, Department of Plant Pathology, Agriculture Research Organization, The Volcani Center, P.O. Box 6, Bet Dagan 50250, Israel. Phytopathology 84:1416-1421. Accepted for publication 18 August 1994. Copyright 1994 The American Phytopathological Society. DOI: 10.1094/Phyto-84-1416.

Effects of solar radiation intensity and of temperature on wilt induced by Fusarium oxysporum f. sp. dianthi in carnation were examined in seven experiments conducted under conditions in which these parameters were varied. In each experiment, plants were inoculated with F. o. dianthi at four different spore concentrations and grown under screen covers, which produced four different levels of shade with respect to incoming radiation intensity. Disease intensity varied substantially among the seven experiments due to solar radiation intensity or temperature, among the four levels of shade within each experiment, and among inoculum concentrations within each shade level. The most severe epidemics developed at low radiation intensities (200–300 μE m^–2 s^–1) and at temperatures close to 25–26 C. At solar radiation intensities above 1,000 ?E m^–2 s^–1 and temperatures below 18 C plants remained symptomless. Nevertheless, F. o. dianthi was isolated from most of the symptomless plants. In all cases where symptoms were apparent, disease intensity was affected by the inoculum concentration, being more severe as the concentration increased.