In-vitro assessment of fungicidal efficacy against Lasiodiplodia theobromae, the causal agent of root rot in mulberry (Morus alba L.)

Abstract

Root rot of mulberry (Morus alba L.) caused by Lasiodiplodia theobromae has emerged as a major constraint in mulberry cultivation, leading to poor root development, wilting and significant yield losses in sericulture. The present investigation was conducted to evaluate the efficacy of various fungicides against L. theobromae under in vitro conditions using the poisoned food technique. Eighteen fungicides, including six contact, six systemic and six combination formulations, were tested at different concentrations. Among the contact fungicides, Mancozeb 75% WP exhibited the highest mycelial inhibition (up to 72.35%), whereas Copper oxychloride 50% WP showed the least effect. Systemic fungicides such as Propiconazole 25% EC, Tebuconazole 25% WP and Carbendazim 50% WP completely inhibited fungal growth (100%) at all tested concentrations. Similarly, combination products like Carbendazim 12% + Mancozeb 63% WP and Azoxystrobin 11% + Tebuconazole 18.3% SC also achieved complete inhibition. The findings clearly demonstrate that systemic and combination fungicides, especially triazole- and benzimidazole-based formulations, are highly effective against L. theobromae. These fungicides can be recommended for inclusion in integrated disease management (IDM) programs to control root rot in mulberry and sustain healthy sericulture production systems.