Yield response of Fusarium infected maize seed treated with biological control agent formulations

Abstract

Potential vegetative and reproductive increases in yield, as well as the biological efficacy against Fusarium verticillioides and F. proliferatum causing ear and stem rot in maize crops of commercially-formulated micro-organism formulation T-Gro (Trichoderma harzianum isolate DB103 WP) combined with Spartacus (Beauveria bassiana isolate DB 105 WP), T-Gro combined with Armenius (Bacillus subtilis isolate DB 109 WP), T-Gro combined with Maximus (Bacillus subtilis isolate DB 108 WP), T-Gro combined with Shelter (Bacillus subtilis isolate DB 101), T-Gro combined with Bismarck (Microbacterium maritypicum isolate DB 107 WP), as well as individual treatments of T-Gro, Armenius, Bismarck, Maximus and Shelter, were investigated when applied to maize seed and soil under field conditions. All the micro-organism treatments were compared with Thiram 750WP (750g/kg thiram WP) and an untreated control. The micro-organism treatments showed an increase in vegetative as well as reproductive yields when compared to the reference product Thiram 750 WP and the untreated control. There were no observations of adverse effects on the germination of maize seed in all the treatments that were applied. The three isolates B. subtilis, T. harzianum, and M. maritypicum, showed a significant reduction in vascular tissue discolouration of the main and ear stems, indicating a potential to be used in the reduction and control of diseases caused by Fusarium spp. Results also showed poor to very good increases of stem and foliage biomass as well as cob yield per plant produced by the micro-organism treatments when compared to the untreated control. The highest cob yield per plant that differed significantly from the untreated control was produced by T-Gro and Shelter. No phytotoxicity of any kind was observed with the application of the micro-organism formulations and they could therefore be deemed suitable to be used for the treatment of maize seed. The micro-organism formulations containing fungal and bacterial biological control agents have the potential to be used in commercial maize production to increase vegetative and reproductive yields and reduce the severity of ear and stem rot in maize.