Effectiveness of biopesticide formulations of Bacillus subtilis as a growth promoter and disease antagonist in maize

Major maize diseases, such as downy mildew, leaf blight, and rust, pose significant threats to global maize production. This study utilized three types of rhizosphere isolates from the Bacillus subtilis species, known for their antagonistic properties against several important maize phytopathogens and their ability to dissolve phosphate and potassium minerals under laboratory conditions. To further assess the potential of biopesticide formulation, field experiments were conducted to control downy mildew, leaf blight, and rust while also promoting maize growth. The tests involved applying the biopesticide formulation through seed soaking and crop spraying in combination with six maize varieties: Nasa 29, JH 29, HJ 21, Jakarin, Lamuru, and NK6172. The study’s findings demonstrated that applying biopesticide formulations derived from antagonistic bacteria, both at the seed level and through foliar spraying, significantly reduced the severity of major maize diseases across various varieties. Specifically, the treatments were effective against downy mildew in the Nasa 29 and JH 29 varieties, resulting in infection rates of only 0.2% to 0.8%. Leaf blight disease was considerable in the HJ 21, Lamuru, and Jakarin varieties, with infection rates ranging from 15% to 22%. Additionally, rust disease was significantly managed in the Nasa 29, JH 29, Jakarin, and NK6172 varieties, where infection rates varied between 27% and 31%. Moreover, the study indicated that genetic factors of variety play a vital role in influencing the capacity of biopesticide formulations to enhance plant growth.