T. Selvaraj

Management of Early Blight (Alternaria Solani) on Tomato: 1. Host Resistance and Fungicide T. Selvaraj

Among the tested tomato varieties the advanced line CLN2007I showed resistant/tolerant character to the disease and outstanding in fruit yield over the susceptible check and the rest varieties. Furthermore, Bishola, Eshet, H-1350 and Melkasalsa were found to be moderately resistant to the disease. Therefore, these varieties should be cultivated in the study area to tackle the problem. Weekly spray of mancozeb minimizes the disease by 47.75% and consequently improves the yield by 112.48%. Otherwise when it was applied every 21 days minimum disease reduction (14.45%) was observed with yield increment only by 16.76%. High return was obtained from spray of mancozeb at weekly and bi-weekly interval with marginal rate of return 2,671.3% and 1,724.3%, respectively. Therefore, mancozeb with a spray frequency of every week was the most effective in-terms of disease management and economic return. Furthermore, combination of the fungicide with the resistant and moderately resistant varieties can bring down the disease below its economic threshold level. Moreover, other locally registered fungicides of different chemical groups need to be tested to look for wider management options.