Post-germination Application of Trichoderma asperellum for the Biocontrol of Macrophomina phaseolina in Cowpea

Abstract

Cowpea (Vigna unguiculata (L.) Walp.) serves as a food source for humans and forage for animals. However, its production is affected by disease-causing fungi, of which Macrophomina phaseolina is a significant pathogen. Trichoderma was employed as a biofungicide to manage the disease in the screenhouse. Three strains of Trichoderma asperellum were isolated from the soil. The fungal spore suspensions of the Trichoderma strains were prepared, formulated into seven different treatment combinations, and applied to the cowpea potted soil five days after the germination of the cowpea to investigate their biocontrol ability on M. phaseolina and assess their effects on cowpea growth. The experiment's results showed that cowpea plants treated with T. asperellum differed significantly in plant height, stem girth, and leaf number compared to those treated with M. phaseolina alone (p < 0.05). Trt3 (54.6815 cm), Trt1 (54.0125 cm), and Trt5 (52.9375 cm) gave a higher plant height than in control 1 (M. phaseolina-treated cowpea - 44.9667 cm). Also, Trt7 (0.5413) and Trt3 (0.5258) gave a higher stem girth than in control 1 (M. phaseolina-treated cowpea - 0.3333 cm), while Trt6 (20.292) gave a higher leaf number than in control 1 (M. phaseolina-treated cowpea - 8.833). Additionally, Trt3 and Trt7 exhibited disease incidences of 22% and 67%, respectively, compared to control 1, which had a 100% incidence. Meanwhile, Trt7 showed 8% disease severity, compared to control 1, which had 100%. Therefore, post-germination Trichoderma application proved to be an effective strategy for controlling M. phaseolina, and it also has the potential to enhance cowpea biomass for sustainable food security.