Enhanced Control of Pepper Anthracnose through Co-Application of Paenibacillus polymyxa GYUN-2285 and Pseudomonas protegens GYUN-2679

Anthracnose disease caused by <i>Colletotrichum</i> species is one of the most economically important, frequently leading to substantial yield and quality losses. This study investigated the biocontrol potential of two rhizosphere-associated bacteria, <i>Paenibacillus polymyxa</i> GYUN-2285 and <i>Pseudomonas protegens</i> GYUN-2679 isolated from soil. GYUN-2285 and GYUN-2679 were evaluated separately, and the two strains were subsequently co-applied to examine whether their combined treatment improved pathogen suppression relative to individual applications. Dual culture assays showed that both strains inhibited a broad range of plant pathogenic fungi, including several <i>Colletotrichum</i> species. The combined application of the two strains significantly promoted plant growth, enhancing seedling vigor and development. <i>In planta</i> experiments on pepper fruits revealed that individual applications GYUN-2285 and GYUN-2679 significantly reduced disease serverity. Notably, the combined treatment showed greater numerical suppression than the individual treatments under the tested conditions. This improved performance may be associated with the complementary functional traits of the two bacteria, which may broaden their antagonistic activity against pathogens. These findings suggest that the integration of GYUN-2285 and GYUN-2679 into biocontrol strategies offers a promising, sustainable, and eco-friendly alternative for managing anthracnose in peppers.