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Title: Reactions of 20 melon cultigens to powdery mildew race 2U.S.

item McCreight, James - Jim

Submitted to: Cucurbitaceae Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 8/1/2002
Publication Date: 12/1/2002
Citation: McCreight, J.D. 2002. Reactions of 20 melon cultigens to powdery mildew race 2U.S. In: Maynard, D.N., Wolff, D.W., editors. Cucurbitaceae 2002. Alexandria, VA: ASHS Press. p. 72-77.

Interpretive Summary: Powdery mildew is a serious disease of melon worldwide. The disease is caused by one or two fungi: Sphaerotheca fuliginea and Erysiphe cichoracearum. Early infection can result in reduced yield; late infection may only reduce culinary quality, i.e., sweetness and flavor. There are more than 20 sources of resistance to the 11 races of S. fuliginea, including two variants of race 2 (2France, 2U.S.), and two races of E. cichoracearum, but knowledge of their reaction to other races, inheritances and allelic relationships is often unknown, incomplete, or has not been verified. For example, Sowell and Corley reported high level resistance in PI 234607 and 16 other accessions, and lower level resistance in PI 179901 to SF race 2 (prior to differentiation of the French and U.S. variants), yet the inheritance of resistance to race 2 in these 18 cultigens remains unknown. Moreover, the reactions of all the PM resistance sources to one or more particular races of PM have not been reported. The objective of the present study was to compare 20 melon cultigens for reaction to PM race 2U.S. in a Salinas, California greenhouse and compare the results with previously published reports on their reactions to race 2.

Technical Abstract: Powdery mildew, incited by Sphaerotheca fuliginea (Schlecht ex Fr.) Poll., reduces yield and quality of melon (Cucumis melo L.) production worldwide. Twenty melon cultigens, including 11 powdery mildew race differentials, were evaluated for their reaction to S. fuliginea race 2U.S. in a greenhouse. Ten of the 11 powdery mildew race differentials reacted as expected to S. fuliginea race 2U.S. Iran H, one of the differentials, which had not been tested previously against race S. fuliginea 2U.S., was susceptible. 'Perlita', 'Seminole', PI 234607, PI 236355, and PI 313970 were resistant. "Amarillo', 'Negro', and 'Moscatel Grande' and PI 179901 were susceptible to S. fuliginea race 2U.S. The resistance reactions of MR-1, PI 124111, PI 124112, and PI 313970 included water soaked spots, and, with the exception of PI 124112, resistant-blisters.