Screening of Grape Varieties for Resistance to Anthracnose under Natural Conditions

Abstract

Grape (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 is responsible for yield losses of up to 80-100 per cent and also adversely affects fruit quality and marketability under favourable conditions. Anthracnose severity was evaluated on eight grape varieties during the back pruning seasons of 2024 and 2025 at Raichur. Thompson Seedless showed the earliest onset, fastest progression and highest. Per cent disease index (PDI) (100% in both years) with the highest area under disease progress curve (AUDPC) and apparent infection rate. Other varieties recorded high PDI such as Manik Chaman (85.25-88.63%), 2-A Clone (79.25-84.73%), Sharad Seedless (69.50-65.73%), K.R. White (66.63-62.25%), Manjari Naveen (64.25–59.63%), Fantacy Seedless (58.75-53.75%) and Medica (62.73-57.25%). Fantacy Seedless and Medica progressed slowly, while Sharad Seedless, K.R. White and Manjari Naveen were moderately progressed. All varieties were classified as highly susceptible, emphasizing varietal differences and the need for timely disease management.