Influence of particle size and dispersibility of agricultural fungicide penthiopyrad on fungicidal efficacy against plant disease

Abstract

Influence of particle size and dispersibility of penthiopyrad on the fungicidal activity against plant disease was investigated. Suspension concentrates (SC) containing 20% penthiopyrad particles prepared into different particle sizes; 8.7, 4.5, 1.5, 0.30 and 0.24 μm of mean diameter were tested in a greenhouse. The activity of penthiopyrad against cucumber powdery mildew and tomato gray mold at a dose of 100, 20, 4 ppm was evaluated. Regarding rainfastness in case of cucumber powdery mildew, SC containing coarsest penthiopyrad and also agglutinated finest diameter were more effective than others. On the other hand, in case of residual effect against tomato gray mold, SC containing dispersed fine diameter were more effective than others. The results indicate that penthiopyrad SC containing fine diameter and controlling its dispersibility is effective to improve the rainfastness of cucumber powdery mildew and residual effect of tomato gray mold.