Efficacy of Fungicides, Botanicals and Trichoderma viride against Alternaria Leaf Spot of Okra (Abelmoschus esculentus L.)

Abstract

Alternaria leaf spot, caused by Alternaria alternata, is a significant fungal disease affecting okra (Abelmoschus esculentus L.), leading to considerable yield losses. This study investigates the efficacy of selected fungicides, botanicals, and Trichoderma viride in managing this disease, while assessing their effects on plant growth and the economic viability of the treatments. A field experiment was conducted using a randomized block design with eight treatments, including fungicides like mancozeb and carbendazim, botanicals such as neem oil, garlic, ginger extracts, and the biocontrol agent Trichoderma viride. The results showed that the combination of mancozeb (12%) and carbendazim (63%) was the most effective, resulting in the tallest plant height of 89.32 cm at 90 DAS, the lowest disease intensity of 8.10% at 45 DAS, and the highest yield of 14.81 t/ha. This treatment also resulted in the highest cost-benefit ratio of 1:2.94. Among the botanicals, neem oil and garlic extract showed moderate effectiveness in disease management. Trichoderma viride also contributed to significant disease suppression and plant growth enhancement. The cost-benefit analysis indicated that chemical fungicides provided the highest economic return, although botanicals and biocontrol agents offer sustainable alternatives. This study demonstrates that integrating chemical, biological, and botanical treatments can effectively manage Alternaria leaf spot in okra, with Trichoderma viride offering a promising eco-friendly option.