Enhancing Biotic Stress Tolerance in Soybean Affected by Rhizoctonia solani Root Rot Through an Integrated Approach of Biocontrol Agent and Fungicide

Rhizoctonia solani causes root rot in soybean, a worldwide severe concern for soybean cultivation. The fungus grows and clogs the xylem tissue of the host plant by producing numerous sclerotia, which results in disease symptoms, such as yellowing of leaves, wilt, and plant death. Overuse of chemical fungicides increases the threat of developing resistance to pathogens, reduces soil productivity, and negatively impacts the health of the soil, the environment, and humans. An integrated pest management strategy improves crop yield, profit, and safety. The present study focused on a fungicide (carbendazim) compatibility test with a biocontrol agent (Pseudomonas fluorescence). It evaluated the effect of this combined approach on photosynthetic reactions and growth in soybean in the presence of the fungal pathogen R. solani. The study showed that P. fluorescence significantly inhibited the mycelial growth of R. solani (43%) and tolerated 0.05-0.15% concentration of carbendazim. This confirms the suitability compatibility of P. fluorescence with chemical fungicides for IPM. These novel blending significantly reduced the disease incidence by about 75%, and a 72% decrease in disease severity was observed compared to pathogen control. Moreover, this combined approach has also improved plant growth, yield parameters, and photosynthetic efficiency in the presence of R. solani treated with an integrated system showed better overall growth despite being infected by the pathogen.