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ARS Home » Pacific West Area » Salinas, California » Crop Improvement and Protection Research » Research » Publications at this Location » Publication #314500
Title: Cucurbit powdery mildews: Methodology for objective determination and denomination of races

Author
item LEBEDA, A - Palacky University
item KRISTKOVA, E - Palacky University
item SEDLAKOVA, B - Palacky University
item McCreight, James - Jim
item COFFEY, MICHAEL - University Of California

Submitted to: European Journal of Plant Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/20/2015
Publication Date: 2/1/2016
Citation: Lebeda, A., Kristkova, E., Sedlakova, B., Mccreight, J.D., Coffey, M.D. 2016. Cucurbit powdery mildews: Methodology for objective determination and denomination of races. European Journal of Plant Pathology. 144:399–410. doi: 10.1007/s10658-015-0776-7.

Interpretive Summary: Cucurbit powdery mildew (CPM) is the most common disease on field and greenhouse cucurbit crops worldwide. CPM is caused most frequently by two fungi that are highly variable in their ability to infect cucurbits. Numerous pathogenic races (nearly 50 of one of the fungi) have been identified on cucurbits, mostly on melon (i.e., cantaloupe, honeydew, etc.), and various, independent systems of CPM race determination and denomination have been used worldwide. We briefly reviewed historical perspectives and the current state of understanding of the variation of the two CPM pathogens at the pathogenic race level, their differentiation and designation. We propose a unified approach for CPM race designation that is comprised of five components of equal importance, none of which can be omitted. Adoption and implementation of this approach by the international CPM research, breeding, seed and production community will enhance research, communication and management of CPM races.

Technical Abstract: Cucurbit powdery mildew (CPM), a disease on field and greenhouse cucurbit crops worldwide, is caused most frequently by two obligate erysiphaceous ectoparasites (Golovinomyces orontii s.l., Podosphaera xanthii) that are highly variable in their pathogenicity and virulence. Various, independent systems of CPM race determination and denomination are used worldwide, having to date been differentiated on different cultivars or lines of melon (Cucumis melo L.). We briefly review historical perspectives and the current state of understanding of the virulence variation of the two CPM pathogens at the pathogenic race level, their differentiation and designation. Furthermore, we propose for use by the international CPM research, breeding, seed and production community new tools to enhance research, communication and management of CPM. Our newly proposed package consists of five components: 1) a set of 21 differential genotypes of Cucumis melo L. for the identification of CPM races; 2) a triple-part, septet code for meaningful, concise designation of CPM races; 3) protocols for maintenance of CPM isolates, differential genotypes, and laboratory assays; 4) rules and principles of practical application of this system in breeding, seed production and cucurbit growing, including a proposal of a race denomination suitable for practical application; 5) crucial activities leading to the implementation and running of new tools for CPM research and management. The five components of this package have equal importance, forming a compact system, and none of them can be omitted.