Evaluation of the Antifungal Efficacy of Biopesticides on the Growth of <i>Sclerotium rolfsii</i> Isolates from Vegetable Crops in Côte d’Ivoire

Abstract

Sclerotium rolfsii Sacc. is a polyphagous telluric fungus responsible for a large number of diseases affecting the yield of horticultural crops, particularly vegetables. Conventional methods of controlling this pest, which involve the use of synthetic fungicides, are toxic for the environment and consumer’s health. The aim of this study was to evaluate in vitro the efficacy of five biopesticides (NECO 50 EC, ASTOUN 50 EC, FERCA 50 EC, BIOSAKINE 50 EC and NORDINE 50 EC) on the mycelial growth of five (5) S. rolfsii isolates from different localities in Côte d’Ivoire. For each biopesticide, seven (7) concentrations (100; 200; 400; 600; 800; 1000 and 2000 ppm) were tested. The experiment was repeated 3 times over time in the Laboratory of the Plant Physiology and Pathology Teaching and Research Unit of the UFR Biosciences. The effect of the biopesticides was compared with that of two reference fungicides, azoxythrobin and chlorothalonil combined with carbendazine, at concentrations of 0.1; 1; 5; 10; 25; 50 and 100 ppm. Each concentration was incorporated into Potatoes Dextrose Agar (PDA) culture medium after cooling to 45°C. The efficacy of these products was assessed by measuring the mycelial growth of the various isolates on the reverse side of the Petri dishes on two perpendicular axes every day, over a period corresponding to the complete growth of the unamended controls. The results of the study show that the fungicides applied have different levels of toxicity on S. rolfsii isolates. The biopesticides NECO 50 EC and ASTOUN 50 EC effectively inhibited mycelial growth in 60% of isolates at the 800 ppm concentration. Mycelial growth of all isolates (100%) was effectively inhibited at concentrations of 1000 and 2000 ppm three days after incubation. The use of these biopesticides would be an alternative to the use of synthetic fungicides.