Integration of Fungicides and Crop Cultivars for The Management of Cowpea Root Rot in Batticaloa, Sri Lanka

Abstract

Cowpea is a major grain legume cultivated in the drier regions of Sri Lanka. Its plant stand and yield are adversely affected by root infections resulting from soil-borne pathogenic fungi. Cowpea production is severely constrained by Fusarium root rot caused by Fusarium solani. This study hypothesized that integrating resistant cowpea cultivars with fungicides could improve disease management under field conditions in Batticaloa, Experiments were conducted to evaluate the integrated use of four cowpea cultivars (Bombay, Dhawala, Waruni, and Wijaya) and three fungicides (captan, homai, and topsin) for managing F. solani root rot. The study was arranged in a factorial randomized complete block design with 16 treatments and three replications. Before the field experiment, an in vitro study was conducted to culture the fungal growth of F. solani on potato dextrose agar. After culturing, the pathogen was inoculated by soil drenching, followed by fungicide application to evaluate cultivar–fungicide interactions. Disease incidence, disease severity, total grain weight, 100-seed weight, and total dry pod weight were recorded. The Bombay × topsin combination significantly reduced disease severity. Among the cultivars, Wijaya recorded the lowest disease incidence and severity and the highest grain yield. Topsin and homai effectively reduced disease incidence and severity while improving grain yield. Overall, Wijaya combined with topsin or homai was identified as the most effective strategy for managing Fusarium root rot in cowpea under Batticaloa conditions. These findings provide a practical integrated disease management strategy to reduce yield losses and promote sustainable cowpea production in Sri Lanka.