In-vitro Efficacy of Fungicides against Grape Anthracnose Caused by Colletotrichum gloeosporioides

Abstract

Grapevine (Vitis vinifera L.) is an economically important fruit crop, but its production is severely constrained by several fungal diseases such as downy mildew (Plasmopara viticola), powdery mildew (Erysiphe necator), anthracnose (Colletotrichum gloeosporioides) and Botrytis bunch rot (Botrytis cinerea). Among them anthracnose caused by Colletotrichum gloeosporioides significantly reduce 80-100 per cent yield, fruit quality and marketability under favourable conditions. An in vitro study was conducted to evaluate the efficacy of contact, systemic and combination fungicides at three concentrations against the pathogen. Among the contact fungicides chlorothalonil 75% WP and copper oxychloride 50% WP recorded the highest inhibition (67.78% at 0.30% concentration), were more effective, while others showed only moderate inhibition. Among systemic fungicides, thiophanate methyl 70% WP and tebuconazole 25.90% EC achieved complete inhibition (100%) at all tested concentrations, followed by hexaconazole 5% EC (96.11% at 0.30% concentration) and propiconazole 25% EC (92.59% at 0.30% concentration). Combination fungicides were highly effective, with fluopyram 17.7% + tebuconazole 17.7% SC recorded 100 per cent inhibition at all concentrations, while tebuconazole 50% + trifloxystrobin 25% WG (91.85% at 0.30% concentration) performed significantly better than others. These results indicated that triazole-based systemic fungicides and combination formulations, particularly tebuconazole, propiconazole and tebuconazole + trifloxystrobin were most effective in inhibiting mycelial growth of C. gloeosporioides, highlighting their potential in the management of grape anthracnose.