In Vitro Evaluation of Different Fungicides against Collar Rot Caused By Sclerotium Rolfsii in Yard Long Bean (Vigna Ungiculata)

Abstract

Yard long bean (Vigna ungiculata) is one of the most essential and widely cultivated common vegetable crops grown in Sri Lanka. Damping off of seedlings threatens yard long bean production by killing a large number of seedlings and as the infection is usually not lethal it reduces the plant growth and the quality and quantity of the yield. This is a common issue in yard long bean nurseries which leads to patches in nursery beds and the affected plants are generally found in scattered areas. It has the potential to cause severe loss in yard long bean production. This disease is commonly caused by Sclerotium rolsfii, and is widely distributed throughout the world. This study will be undertaken to investigate the efficacy of six recommended fungicides and one fungicide which is not recommended i.e. Captan 80% WDG for controlling collar rot. The experiment was arranged in a Completely Randomized Design (CRD) with eight treatments randomized in five replicates.  These fungicides were evaluated at recommended concentrations on the growth of Sclerotium rolfsii in Potato dextrose agar (PDA) medium using poisoned food technique, in vitro.  The result shows that the effect of Mancozeb 75% WP, Captan 50% WP, Captan 80% WDG and Homai WP has been highly effective in suppressing radial expansion as well as percent inhibition of the fungus at recommended concentrations compared with Thiram 80% WP. Carbendazim 50% WP and Topsin 70%WP did not control the disease. Based on study findings, we can recommended Captan 80% WDG and assess the proper fungicide concentrations to reduce probable toxicities due to excess application and reduce the wastage of money in order to improve profit.