EPIDEMIOLOGY OF TOMATO SPOTTED WILT IN PEPPER AND TOMATO IN SOUTHERN GEORGIA

The spatial distributions of symptomatic tomato and pepper plants infe cted with tomato spotted wilt virus (TSWV) were mapped over time in fi eld studies in 1990 to 1992. Disease gradients occurred in some tomato transplant beds and pepper fields but were not observed in tomatoes g rown to maturity. In 1990 and 1991, an increasing gradient emanated fr om the eastern edge of tomato transplant beds and led to adjacent toba cco plots containing TSWV-infected plants. In addition, gradients with in each block emanating from the edge adjacent to fallow alleys were o bserved within the primary disease gradient in 1990. A gradient also o ccurred both down the row and across cultivars in a commercial pepper field in 1990. The gradient failed to flatten over time, a possible in dication of lack of secondary disease spread. Tests for aggregation su pported the contention that there was limited secondary spread within pepper fields and tomato plots and that most infections arose from pri mary transmission. Clipped plants from tomato transplant beds had no h igher incidence of TSWV in grow-out tests than did nonclipped plants. Reduced yields were significantly correlated with time of first sympto m expression in tomato, with plants that were symptomatic earlier in t he season yielding less fruit per plant by weight.