Potential of seed treatment fungicides for the control of foliar diseases of tomato under late short growing season conditions of a tropical derived savanna

Abstract

Improved adapted varieties of tomato were used to test the efficacy of prophylactic seed treatment with the fungicides benomyl and thiram, in the late short growing season of a tropical derived savanna. The blotter technique was used to evaluate the effect of the fungicides on seed mycoflora and seed germination. Laboratory tests revealed seed infection by Fusarium spp. and showed that treated seeds performed better than those of the control. Despite the high incidence and severity of Septoria leaf spot and Alternaria leaf blight in the fie1d, the number of severely infected leaves recorded 28 days after transplanting (DAT) was significantly (P"0.01) lower in the fungicide-treated than in the control plots. The fungicides were effective in maintaining considerably lower disease levels in treated plots up to flowering. However, early differences in disease severity did not translate into yield differences, because by the time of fruit set and fruit filling disease levels were the same. Our results suggested limited translocation of fungicides in time to control polycylic infection of new growth, and emphasized the necessity to combine seed treatment with other control options. Use of seed treatment in combination with limited spraying with an appropriate fungicide could potentially reduce the high costs and hazards of frequent fungicide application in tomato grown during the wet season.