EFFICACIES OF FUNGICIDES IN CONTROLLING SPOT BLOTCH OF BARLEY

Abstract

Efficacies of 12 fungicides in inhibiting growth of Bipolaris sorokiniana on potato dextrose agar and development of spot blotch symptoms in barley leaf segments inoculated with B. sorokiniana were examined. Efficacies in growth inhibition were high (EC95, 2–40 ppm) for RH-2161, fentin hydroxide, thiram, and carbathiin; intermediate (EC95, 250–500 ppm) for triadimefon, anilazine, captafol, and dodine; and low (EC95, [Formula: see text]) for captan, chlorothalonil, mancozeb, and metiram. In symptom inhibition assays, RH-2161 was extremely effective (EC95, 70 ppm), and anilazine, chlorothalonil, fentin hydroxide, mancozeb, triadimefon, and captafol were highly effective (EC95, 150–300 ppm). Efficacies of foliar applications of six fungicides in controlling spot blotch and promoting yield of barley in the field were also examined. Triadimefon, RH-2161, and fentin hydroxide were applied at 0.25 kg a.i./ha and chlorothalonil, anilazine, and mancozeb at 2 kg a.i. ha−1 at barley growth stages 8, 10.1, and 10.4 (Feekes’ scale). Disease severity was significantly reduced in barley treated with mancozeb, RH-2161, chlorothalonil, fentin hydroxide, triadimefon, and anilazine by 63, 68, 68, 77, 82, and 88%, respectively, compared to checks. All fungicides except chlorothalonil significantly increased 1,000-kernel weights of treated plants in the range of 11–15%. Anilazine, triadimefon, and RH-2161 performed better than other fungicides evaluated in the field.