Studies On The Inhibitive Spectrum And The Synergism Of 25% Amistar SC And Its Efficacy In The Main Apple Diseases Regulation

The application technology of Amistar, a new Strobilurin fungicide, had been studied. Its fungicidal spectrum, field trials against Podosphaera leucotricha (Ell.et. Ev.) Salm, Alternaia mali Roberts and Venturia inaequalis (Cooke) Winer, safety assessment to apple trees, and synergism with Carbendazim and Tebuconazol were tested. The main results are as follow:1. The EC50 of Amistar against 16 pathogens were lower than 6ug/ml, and it had the most intensive fungicidal activity against Botrytis civerea and Alternaria Solani, the values of EC₅0 were about 2.2 ug/ml.2. Compared with the standard fungicide, 25% Amistar SC had obvious control effectiveness against Podospnaera, Leucotricha, Alternaia mali and Venturia inaequalis. With the increasing of sprayings, the control effectiveness increased. After 7 days of the 3rd spraying, the control effect of 2 000 times against Podospnaera, Leucotricha, and 1 500 times against Venturia inaequalis reached 91.23% and 89.02%, respectively. At the period of autumn growth stoping development, the control effect of 1 500 times against Alternaia mali was 90.31%.3. The results of safety assessment indicated that Amistar had no photoxicity on the six apple varieties, Aozhouqinping, Huangyuanshuai, Beidou, Xinhongxing, Hongfushi, Qingguan, at high concentration. But had serious phtotoxicity to Gala,causing the serious defoliating and blank-brown plague on the apple surface, and influencing the normal development of the tree strongly.4. The synergistic action of mixture of Amistar with Carbendazim and Tebuconazol indicated that the toxicity of different mixed proportion improved remarkably. SR values were over 1.5. When ratios of Amistar to Carbendazim were ranged 1:7 to 1:9, and ratios of Amistar to Tebuconazol were ranged 1:3.29, It rached 3.42⁹.59 and 1.63. It showed significant syneristic action.5. The statistic analysis of synerism of mixture of amistar with Carbendazim and Tebuconazol indicated that the trail efficacy of different rations of Amistar to Carbendazim and Tebuconazol against Alternaia mali were significant in contrast with those of the 3 single fungicides at 0.05 levels.