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Effect of acibenzolar-S-methyl, strobilurins and other fungicide treatments on phylloplane fungi of crops

Chung, Wen-Hsin, Deepak, Saligrama Adavigowda, Ishii, Hideo
Journal of general plant pathology 2013 v.79 no.2 pp. 128-135
Alternaria, Aureobasidium, Cladosporium, Epicoccum, Fusarium, Myrothecium, crops, cucumbers, cultivars, fungicides, leaves, mancozeb, pears, phylloplane fungi
Strobilurins, broad-spectrum fungicides used to control various diseases, may also inhibit the growth of nontarget fungi in the natural environment. Acibenzolar-S-methyl (ASM) is a plant activator; however, the effect of ASM on the growth of microflora on the leaf surface is not clear yet. ASM, strobilurins and other fungicides were sprayed on Japanese pear and cucumber plants in the field. Variations in the morphological characteristics and rDNA-ITS nucleotide sequence of isolated phylloplane fungi were evaluated. The isolation frequency of Alternaria spp., Aureobasidium spp., Cladosporium spp. and Myrothecium spp. on Japanese pear leaves treated with kresoxim-methyl and polycarbamate was lower than on nontreated pear leaves. Moreover, the frequency of Alternaria spp., Cladosporium spp., Epicoccum spp. and Fusarium spp. on leaves of two cucumber cultivars treated with azoxystrobin, triflumizole and mancozeb was lower than the frequency of fungal isolation on nontreated cucumber leaves. The effect of ASM on fungal isolation frequency was not significantly different from that on nontreated pear or cucumber leaves. The fungal genera observed and isolation frequency on the leaves treated with polycarbamate, azoxystrobin, triflumizole and mancozeb tended to be reduced compared to the no-spray treatment.