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Poster: Biology & Disease Mgmt: Mycology


Fungicide resistance and host susceptibility of Colletotrichum orbiculare infecting cucurbit crops in North Carolina
N. NO√čL (1), L. Quesada-Ocampo (1) (1) NCSU, U.S.A.

Cucurbit anthracnose, caused by the ascomycete Colletotrichum orbiculare syn. lagenarium, is a widespread fruit and foliar disease that results in yield losses across the United States. In North Carolina, favorable environmental conditions, host availability, and long growing seasons offer ample opportunity for disease development, resulting in significant economic losses. Application of effective fungicides and planting of resistant cultivars, along with appropriate cultural practices, have proven effective in reducing anthracnose. However, the appearance of new races of the pathogen and development of fungicide resistance has limited the efficacy of these control strategies. The objective of this study is to characterize C. orbiculare populations infecting cucurbit crops in North Carolina, determine their sensitivity to fungicides, and their virulence in watermelon cultivars. Isolates obtained from cucurbit fields in North Carolina and elsewhere for comparison, where evaluated for fungicide sensitivity in vitro with several fungicides and various concentrations. Local isolates of different races were used to evaluate host susceptibility of 24 popular cultivars of watermelon (Citrullus lanatus) in field and greenhouse trials. Results indicate that an integrated disease management strategy that combines effective fungicides and host tolerance will be required to control cucurbit anthracnose in North Carolina.