Biological control of maize seed pathogenic fungi by use of actinomycetes

The effectiveness of two Streptomyces spp. strains to control pathogenic fungi was studied in stored maize grain. The treatments included seed disinfection and inoculation with Streptomyces spp. strains previously isolated from maize rhizosphere. Actinomycete inoculum consisted of filtered suspension and total suspension of fermentor-produced Streptomyces spp. strains biomass. Treatments with Streptomyces spp. strains alone effectively suppressed the development of Aspergillus spp., Curvularia lunata, and Drechslera maydis and significantly (p less than or equal to 0,05) reduced the incidence of Fusarium subglutinans and Cephalosporium acremonium. Among the inoculation treatments, nondisinfested seed inoculated with filtered suspension was the only treatment that did not suppress the development of Penicillium spp. Maize seed inoculation with total suspension of strains was the most effective treatment to control the incidence of seed pathogenic fungi. The development of the Diplodia maydis was only suppressed by the combination of seed disinfection and inoculation with total suspension of strains. Although, the strain DAUFPE 11470 showed the greatest effectiveness for controlling the fungi pathogenic to seed, root and shoot development was reduced by treatment with this strain. The results indicate that Streptomyces spp. strains reduce the incidence of seed pathogenic fungi and have potential as a biological control agent. However, an efficient method of seed treatment with the biological control agent must be developed before it can become an agricultural practice.