Biological Control of Stenocarpella maydis in Maize Seed with Antagonistic Streptomyces sp. Isolates

The effectiveness of two Streptomyces sp. isolates, isolated from maize rhizosphere soil and designated as DAUFPE 11470 and DAUFPE 14632, was evaluated in vitro and under greenhouse conditions for control of Stenocarpella maydis in maize seeds. Stenocarpella maydis incidence was detected in all subsamples of disease-free maize seeds by in vitro survey test, and ranged from 10.8% to 65.2%. In a filter paper test with surface-disinfected seeds inoculated with S. maydis, Streptomyces sp. isolates DAUFPE 11470 and DAUFPE 14632 significantly reduced (P £ 0.05) the pathogen incidence by 93.2% and 92.3%, respectively. Seed germination in the same treatments was increased by 30.0% and 28.2%, respectively. Treatments of nondisinfected seeds with the isolates DAUFPE 11470 and DAUFPE 14632, under greenhouse conditions reduced disease incidence in the seedlings by 87.3% and 85.6%, respectively. The reductions in disease incidence in surface-disinfected seeds were 85.0% and 83.0% for the same isolates. Seedling emergence significantly (P £ 0.05) increased in disinfected and nondisinfected seeds inoculated with the Streptomyces sp. isolates. The results indicate the potential of using Streptomyces sp. isolates as an additional tool to control Stenocarpella ear rot by significantly reducing the incidence of S. maydis in maize seeds and seedlings