Fungicidal Activity of a Medium-chain Fatty Acids Mixture Comprising Caprylic, Pelargonic and Capric Acids

摘要

This study examines the fungicidal activity of a medium-chain fatty acids mixture comprising caprylic acid (C8:0), pelargonic acid (C9:0) and capric acid (CI 0:0), against Rhizoctonia solani, Phytophthora infestans, Colletotrichum gloeosporioides, Botrytis cinerea, Fusarium oxysporum and Sphaerotheca cucurbitae. The mixture of caprylic, pelargonic and capric acids (2/5/3, w/w/w) is prepared into a micro-emulsion concentrate and tested for its inhibitory effect on fungal growth using disc diffusion method except for S. cucurbitae using pot bioassay method. Results show that the fatty acids mixture is self-stabilized under either 4°C during a seven-day-storage or 54°C during fortnight. The doses of the mixed fatty acids completely inhibiting the mycelial growth are 100 ppm for P. infestans and 125 ppm C. gloeosporioides after three days and 200 ppm for B. cinerea after 4 days. A dose of 100 ppm reduces the mycelial growth ini?. solani by 93.7% after 4 days and that in F. oxysporum by 92.9% after 3days. For S. cucurbitae, a dose of 250 ppm results in a control effect of 81.0% in the pot bioassay. Our study provides so far the first report of the fungicidal activity of medium-chain saturated fatty acids mixture at relative low dosage rates.