Potential of Trichoderma harzianum OC12 as biological control against Fusarium wilt of Capsicum frutescens L.

Abstract

Fusarium wilt caused by Fusarium oxysporum f. sp. capsici is a major constraint to cayenne pepper production in Indonesia. Excessive reliance on synthetic fungicides has led to environmental degradation and reduced soil microbial diversity, highlighting the need for sustainable alternatives. This study evaluated the effectiveness of different doses of Trichoderma harzianum OC12 as a biological control agent against Fusarium wilt in cayenne pepper (Capsicum frutescens L.). The experiment was conducted using a completely randomized design with five treatments: control (without T. harzianum OC12) and four doses of T. harzianum OC12 formulated on corn-rice solid medium (12, 16, 20, and 24 g per polybag), each replicated four times. Disease incidence, incubation period, plant height, number of leaves, and root length were recorded. Results showed that T. harzianum OC12 significantly reduced Fusarium wilt incidence and enhanced plant growth parameters. The highest dose (24 g/polybag or 24 g in 2 Kg topsoil) resulted in the lowest disease incidence (16.5%) compared with 100% disease incidence in the control. Additionally, this treatment significantly increased plant height, leaf number, and root length. These findings indicate that T. harzianum OC12, particularly at 24 g/polybag, is an effective and environmentally friendly biological control agent for managing Fusarium wilt in cayenne pepper cultivation.