Assessment of bio-efficacy of Glomus versiforme and Trichoderma harzianum in inhibiting powdery mildew disease and enhancing the growth of cowpea

The current study was conducted to assess the antagonistic bio-efficacy of using wild type and mutant isolates of Glomus versiforme (AMF) and Trichoderma harzianum (TH) in inhibiting powdery mildew disease and enhancing growth of cowpea in a screen house pot experiment. In all, both singly and co-inoculation, eleven treatments were applied as follows: AMFwild, AMF30, AMF60, AMF90, TH, AMFwild + TH, AMF30 + TH, AMF60 + TH, AMF90 + TH, Pathogen alone and control. Results of preliminary antagonistic assay reveal that, using the bio-agents Trichoderma harzianum and Glomus versiforme inhibited the cowpea pathogen Erysiphe flexuosa. Cowpea growth measurements and disease assessment were taken after 7 weeks. All treatments significantly (P < 0.05) enhanced seedling agronomic growth parameters when compared to the control. Treatment AMF60 + TH showed maximum increases in plant height, shoot fresh weight, root dry weight, number of leaves, root length and leaf area. AMF colonisation was found highest in single inoculations of AMF, although this decreased with the addition of T. harzianum. Maximum reduction in disease incidence and severity was recorded in treatment AMF60 + TH in comparison to the control plants. Also, seed treatment further established the biocontrol efficiency of the bioagents and a significant (p < 0.05) increase in seeding germination was recorded when compared with the control. These findings demonstrated that seed and soil treatments with co-inoculation of Glomus versiforme and T. harzianum enhanced the resistance of cowpea seedlings against powdery mildew disease caused by Erysiphe flexuosa and can also be used to enhance growth in cowpea seedlings.