Application of mealworm frass, mycorrhiza, and vermicompost against Rhizoctonia root rot disease and their effects on the growth parameters of bean plants

Rhizoctonia root rot caused by Rhizoctonia solani is one of the critical factors influencing bean plants' yield. This study investigates the effects of some biofertilizers for controlling R. solani and their impact on the growth parameters of bean plants in the greenhouse. Biofertilizers, Funneliformis mosseae (F. mos), vermicompost (Verm), and mealworm frass (Meal), were used in a completely randomized design with five replications. Compared with diseased control, biofertilizers applied separately or in combination, reduced disease severity (except Meal) and disease incidence (except Verm). The combination of Meal + Verm had the best effect on both indices. All biofertilizer treatments increased the dry root weight (except Verm and F. mos + Meal + Verm), fresh root, and foliage weight. Also, root length, and dry foliage weight was increased only in combination treatments, and stem length in Meal + Verm and F. mos + Verm. The highest growth of foliage parameters, root length, and fresh and dry root weight was observed in Meal + Verm, F. mos + Verm, and F.mos + Meal, respectively. The highest mycorrhizal colonization was in F. mos and F. mos + Verm. Therefore, combinations of biofertilizers had better effects on the plant growth and inhibition of Rhizoctonia root rot. The tested biofertilizers and their combinations could be considered as promising tools for reducing the use of chemicals and enhancing sustainable agriculture and disease management. The appropriate timing and application rates for these biofertilizers must be determined accurately during field experiments.