Effect of Trichoderma spp. application timing on the control of Fusarium wilt and vegetative growth of cayenne pepper

Abstract

Cayenne pepper (Capsicum frutescens L.) is a valuable horticultural crop, yet its productivity is frequently reduced by Fusarium wilt caused by Fusarium oxysporum f. sp. capsici. Although Trichoderma spp. is widely known as a biological control agent, the optimal timing for its application to achieve maximum disease suppression and plant growth enhancement remains insufficiently studied. This research aimed to evaluate the effect of Trichoderma spp. application timing on the incidence of Fusarium wilt and the vegetative growth of cayenne pepper. A completely randomised design with five treatments—application at 21, 14, and 7 days before planting, at planting, and a no-treatment control—was used with four replications. Observed parameters included disease incubation period, incidence rate, plant height, number of leaves, and root length. The results showed that Trichoderma spp. application timing significantly influenced all variables (p < 0.05). Application 21 days prior to transplanting resulted in the lowest disease incidence (8%), longest incubation period (28 days), and improved vegetative growth (plant height 66 cm, 33 leaves, root length 17 cm), whereas untreated plants exhibited the highest disease incidence (75%) and the poorest growth. These results suggest that early application of Trichoderma spp. enables effective colonisation of the rhizosphere and may activate induced systemic resistance, thereby enhancing plant defence against Fusarium infection. In conclusion, applying Trichoderma spp. 21 days before planting offers an effective strategy for controlling Fusarium wilt and promoting cayenne pepper growth in a sustainable manner.