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 acid s mixture comprising caprylic acid (C8:0), pelargonic acid (C9:0) and capric acid (C10:0), 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 acid s mixture is self-stabilized under either 4°C during a seven-day-storage or 54°C during fortnight. The doses of the mixed fatty acid s 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 in R. solani by 93.7% after 4 days and that in F. oxysporum by 92.9% after 3 days. 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 acid s mixture at relative low dosage rates.