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Title: Update on powdery mildew resistance screening in watermelon

item Davis, Angela
item Levi, Amnon

Submitted to: HortScience
Publication Type: Abstract Only
Publication Acceptance Date: 3/31/2005
Publication Date: 6/1/2005
Citation: Davis, A.R., Wehner, T.C., Levi, A., King, S.R. 2005. Update on powdery mildew resistance screening in watermelon [abstract]. HortScience. 40(3):871.

Interpretive Summary:

Technical Abstract: The past nine years, powdery mildew has been reported on Citrullus lanatus in Africa and Europe and in the United States the past six years. During this time, it has occurred in the main watermelon production areas in the U.S. and had been documented in nine states (South Carolina, Georgia, Florida, Oklahoma, Texas, Maryland, New York, Arizona, and California). This is of great concern to the watermelon industry since powdery mildew is difficult to control and can have severe impact on yield and fruit quality due to sunscald. Finding resistant C. lanatus germplasm is needed for the development of commercial varieties containing this resistance. This report summarized the status of a project to screen the entire USDA-ARS C. lanatus germplasm collection. Currently, the collection is being screened for race 1 and race 2 Podosphaera xanthii (syn. Sphaerotheca fuliginea auct. p.p.), the causal agent of powdery mildew in C. lanatus. Resistance genes appear to exist for both races and the genes conferring resistance to race 1 appear to be different than race 2 resistance genes.