Effect of selected microbial isolates from maize rhizosphere on disease incidence and severity of maize common smut disease caused by Ustilago maydis

The study was conducted to evaluate the effect of selected microbial isolates from the maize rhizosphere on the incidence and severity of maize common smut disease, which causes a decline in maize production. The rhizosphere contains microorganisms with potential antagonistic activities against microbial diseases. However, there is limited information regarding their use as biocontrol agents. The maize varieties Dk 8033 and Duma 43 were used because they have a short maturity period, are recently released, and are highly preferred by farmers. In-vitro screening of microbial isolates against Ustilago maydis was conducted using the dual culture method in a completely randomized design, with three replicates. Greenhouse experiments followed a completely randomized design with ten treatments, also in triplicate. Data on growth inhibition, disease incidence, and severity were collected. Significant differences (P ≤ 0.05) were observed among isolates. The highest in-vitro inhibition was recorded by fungal isolate MF14 (22.0 mm, unidentified), followed by Serratia sp. (19.0 mm), Bacillus sp. (16.0 mm), and Aspergillus sp. (15.0 mm). In greenhouse trials, MF14 showed the lowest disease incidence (49.3%), while Serratia sp. had the highest (84.3%). These findings highlight the potential of selected microbial isolates, especially MF14, as promising biocontrol agents for managing maize common smut.