Controlling Effects of Several Fungicides against Apple Leaf Spot

Based on the field experiments of 2009-2010 and mycelia growth rate bioassay in laboratory of 2010,the effects of seven fungicides against Alternaria mali Roberts were evaluated.The results indicated that all the tested fungicides showed good effects against the Alternaria mali Roberts with the recommended concentrations in the field or bioassay experiments.Among them,triazole fungicides,such as tebuconazole and difenoconazole had the best inhibitory effects,EC50 values were 1.49 and1.98μg/g,respectively;mancozeb and propineb had less inhibitions on Alternaria mali Roberts,EC50 values were 19.7 and 24.7μg/g,respectively.The results of two years field trials showed triazole fungicides,such as tebuconazole and difenoconazole had significant control effects against the tested pathogenic bacteria with the efficiency of about 85% in spring and autumn tips stage;strobilurin,such as kresoxim-methyl and the antibiotic fungicides of polyoxin and ningnanmycin indicated good effect with the inhabitation rate about80%;the traditional fungicides,such as mancozeb and propineb exhibited low effects against the tested pathogenic bacteria with the inhabitation rate about75%.All these fungicides had no adverse effects on apple tree growth and can be used safely.