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Field Resistance to Potato Stem Colonization by the Black Dot Pathogen Colletotrichum coccodes

November 2009 , Volume 93 , Number  11
Pages  1,116 - 1,122

Nadav Nitzan, Vegetable Forage Crops and Research Unit, USDA-ARS, Prosser, WA 99350; Marc A. Evans, Department of Statistics, Washington State University, Pullman 99164; Tom F. Cummings and Dennis A. Johnson, Department of Plant Pathology, Washington State University, Pullman 99164; Dallas L. Batchelor, Lamb-Weston, Pasco, WA 99301; Chris Olsen, L.J. Olsen, Inc., Othello, WA 99344; Kathleen G. Haynes, Plant Sciences Institute, Genetic Improvement of Fruits and Vegetables Laboratory, USDA-ARS, Beltsville, MD; and Charles R. Brown, Vegetable Forage Crops and Research Unit, USDA-ARS, Prosser, WA 99350

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Accepted for publication 15 June 2009.

Potato (Solanum tuberosum) germplasm was tested for resistance to stem colonization by the black dot pathogen Colletotrichum coccodes. Forty-six potato selections were tested in three field trials from 2006 to 2008. Resistance was determined by comparing disease severity on aboveground stems to the mean disease severity of the industry standards Russet Burbank, Ranger Russet, and Umatilla Russet. The potato selections were also tested for genotype*environment interaction to determine their genetic stability. Heritability of resistance was calculated to be 0.13 with confidence intervals between 0.00 and 0.68. The selections A0012-5, PA95B2-4, PA98NM38-1, and PO94A009-7 had less black dot than the standards in all years, and also demonstrated genetic stability. These selections also possess resistance to the root galling stage of the powdery scab pathogen Spongospora subterranea f. sp. subterranea. PA95B2-4, PA98NM38-1, and PO94009-7 were derived from an introgression program to incorporate resistance to the Columbia root-knot nematode Meloidogyne chitwoodi from the Mexican wild species Solanum bulbocastanum, and also have the commercial cultivar Summit Russet in their ancestry. These selections are promising steps toward sustainable management of black dot and powdery scab and will be further tested and used for breeding purposes.

The American Phytopathological Society, 2009