Effects of Temperature on Disease Development of Tomato Mosaic Virus in Capsicum annuum in Hydroponic Systems. Andrew C. Schuerger, Senior Plant Pathologist; The Science and Technology Office, The Land, Epcot, Walt Disney World Co., P.O. Box 10,000, Lake Buena Vista, Fla. 32830. William Hammer, Research Plant Pathologist, The Science and Technology Office, The Land, Epcot, Walt Disney World Co., P.O. Box 10,000, Lake Buena Vista, Fla. 32830. Plant Dis. 79:880-885. Accepted for publication 10 May 1995. Copyright 1995 The American Phytopathological Society. DOI: 10.1094/PD-79-0880.

Tomato mosaic virus (ToMV) induced severe root, stem, and foliar symptoms when pepper (Capsicum annuum cv. Hungarian Wax) plants were root inoculated in a recirculating hydroponic system during warm summer months. Plant height, root length, root dry weight, and shoot dry weight of root-inoculated peppers were all significantly less than noninoculated control plants. When plants were root inoculated in cooler winter months, plant symptoms were less severe, and only root lengths of inoculated plants were shorter than those of noninoculated control plants. The numbers of local lesions observed on Chenopodium amaranticolor leaves inoculated with nutrient solution or hydroponic filter-sludge samples increased between 28 and 35 days after peppers were root inoculated in a recirculating hydroponic system, regardless of season. The increase in the numbers of local lesions on C. amaranticolor coincided with the occurrence of root symptoms on root-inoculated peppers and is believed to indicate the release of viable ToMV inoculum from infected plant roots. In growth chamber experiments, the ef-fects of temperature on root- or foliar-inoculated peppers were similar; the greatest difference between inoculated and noninoculated plants occurred at 24°C. Moderate or severe symptoms failed to develop on either root- or foliar-inoculated plants incubated at 18°C but were observed on foliar-inoculated plants incubated at 32°C. The severity of foliar systemic symptoms and the rate of disease development were greatest in foliar-inoculated pepper plants incubated at 24°C

Keyword(s): aeroponic, greenhouse, seasonal effects