Evaluation of Bacillus spp. for Controlling Anthracnose Disease in Chili Caused by Colletotrichum capsici

Abstract

Chili is an important economic crop in Thailand. It is widely consumed domestically and exported in various processed forms such as chili powder, chili sauce, curry paste, pickled chili, and dried chili. A major problem in chili production is anthracnose disease, caused by the fungus Colletotrichum capsici, which spreads rapidly and severely during the rainy season under high temperature and humidity conditions. Currently, biological control has played a significant role in the production of safer crops by reducing the use of chemical pesticides, particularly through the application of antagonistic microorganisms such as Bacillus spp. Therefore, this study was conducted to evaluate the efficacy of nine Bacillus spp. isolates and powder formulations of Bacillus spp. in controlling anthracnose disease in chili caused by Colletotrichum capsici. The experiment was arranged in a Completely Randomized Design (CRD). The results showed that all Bacillus spp. isolates significantly inhibited the growth of the pathogen with statistical differences compared to the control. However, isolates A1-2, A1-5, A1-12, A1-15, B1-19, B2-2, B2-6, B2-21 and B2-32 were not statistically different from each other in terms of disease suppression, with lesion sizes ranging from 0.70–1.38 cm. In addition, powder formulations developed from Bacillus spp. in three forms cell suspensions, culture filtrate and cell suspensions + culture filtrate a combination of both were also evaluated for their effectiveness in suppressing anthracnose disease. The results indicated that the powder formulations of each Bacillus spp. isolate exhibited statistically significant differences in disease control efficacy when compared to the control.