In Vitro Antifungal Efficacies of Maize Associated Microorganisms

Microorganisms (bacteria and fungi) were isolated from different parts of yellow maize (stem, cob, husk, leaf, root) as well as from rhizosphere and non-rhizosphere soil of maize using conventional microbiological techniques. A total number of twenty-six bacteria and thirteen fungi were isolated. The antagonistic efficacies of these isolates were tested against Sclerotium rolfsii, Aspergillus repens, Penicillium notatum and Pythium sp. using streak bioassay, food poisoning and dual culture techniques. None of the bacteria was antagonistic to the test fungi at 25°C on PDA using streak bioassay. However, there was reduction in the population density of the test fungi using food poisoning technique. The fungal isolates were antagonistic to the test fungi in varying degrees. Generally, S. rolfsii was susceptible to seven out of the eight fungal antagonists while P. notatum was least susceptible. The percentage reduction of S. rolfsii ranged from 40.00 ± 5.78 to 64.07 ± 2.31. Efficacies of chemical fungicides; mancozeb, camazeb and red force at 3 different concentrations— 0.05%, 0.1% and 1.0% (w/v) on the test fungi were also determined. No growth of the test fungi was observed at 1% (w/v) of all the fungicides while at lower concentration (0.05%), red force did not have any inhibitory effect. The growth of S. rolfsii was completely inhibited at 0.05% of mancozeb whereas there was reduction in mycelial growth of A. repens. Effect of inoculation time and nutrients (PDA and MEA) was determined on the antagonistic activities of Trichoderma viride. There were significant differences in inhibitory potentials of the two isolates of Trichoderma viride when pre-inoculated on the culture medium. The antagonistic potentials were more pronounced on malt extract agar than potato dextrose agar.