ARS | Publication request: Evaluation of watermelon and related species for resistance to race 1W powdery mildew resistance

Submitted to: Journal American Society Hortscience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 16, 2007
Publication Date: December 3, 2007
Citation: Davis, A.R., Levi, A., Tetteh, A., Wehner, T., Russo, V.M., Pitrat, M. 2007. Evaluation of watermelon and related species for resistance to race 1W powdery mildew resistance. Journal American Society Hortscience. 132(6):790-795.

Interpretive Summary: Race 1 and race 2 powdery mildew has been reported on watermelon in the United States for six years. In this study, the entire available U.S. Plant Introduction collection of watermelon species was evaluated for resistance to race 1 powdery mildew. The collection is made up of six species, and our screening showed that wild type watermelon showed more resistance than edible cultivars. Eight of the 1,573 watermelon lines were resistant to race 1 and another 86 demonstrated intermediate resistance. The majority of the lines showing resistance were collected in Zimbabwe.

Technical Abstract: Race 1 and race 2 powdery mildew (Podosphaera xanthii) has been reported on watermelon (Citrullus lanatus (Thunb.) Matsum. & Nakai) in the United States for six years. In this study, the entire available U.S. Plant Introduction collection of Citrullus sp. was evaluated for resistance to P. xanthii race 1 in six replications. The collection is made up of six species, and our screening showed that wild type accessions tended toward resistant more often the Citrullus lanatus var. lanatus. Eight of the 1,573 accessions were resistant to race 1 and another 86 demonstrated intermediate resistance. Cotyledon, stem, and leaf disease severity correlated slightly. The majority of the accessions showing resistance were collected in Zimbabwe.