Control effects of several fungicides against Alternaria alternata
In order to find out effective fungicides against Alternaria alternata , the indoor toxicity and field control effects of 7 fungicides against Alternaria alternata were studied with the method of mycelium growth inhibition. The results of indoor experiments showed that tebuconazole 43% SC presented the highest virulent with the lowest EC50, 0.0018 mg/mL; the EC50 of Iprodione 75% WP, dimethachlon 40% WP, kangchixing No.1 45% WP, polyoxin 3% WP, mancozeb 80% WP and Thiophanate methyl 70% WP were 0.0063, 0.1597, 0.1891, 0.3835, 1.755 and 9.1313 mg/mL, respectively. The results of field experiments showed that tebuconazole 43% SC (diluted to 1/2000) exhibited the best contro1 effect. Seven fungicides in the order of control effect were tebuconazole 43% SC (diluted to 1/2000) > dimethacholn 40% WP (diluted to 1/600) > Iprodione 75% WP (diluted to 1/600) > polyoxin 3% WP (diluted to 1/500) > kangchixing No.1 45% WP (diluted to 1/800) > mancozeb 80% WP (diluted to 1/500) > Thiophanate methyl 70% WP (diluted to 1/700).