Submitted to: ARS Sclerotinia Initiative Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: November 2, 2006
Publication Date: January 17, 2007
Citation: Porter, L., Hoheisel, G., Coffman, V.A. 2007. Identification of Resistance to Sclerotinia sclerotiorium in Peas. NDSU/USDA-ARS 2007 Sclerotinia Annual Meeting, Bloomington, MN January 17-19, 2007, p. 24. Technical Abstract: White mold, caused by Sclerotinia sclerotiorum, can be a serious disease in irrigated and dryland peas in the Pacific Northwest and is considered a serious potential threat to the expanding pea production in the Midwest of the United States. Due to poor economic returns to pea growers, expensive foliar fungicides used to manage white mold are cost prohibiting. Since there are currently no known sources of white mold resistance in peas, identifying resistant pea lines for breeding purposes is desired. Therefore, 498 pea accessions from the Pisum core collection located at the USDA-ARS, Regional Plant Introduction Station (RPIS), Pullman, WA and seven woody-stem pea lines from the John Kraft Germplasm Collection in Prosser, WA, were screened for resistance to white mold. Pea lines were inoculated with the white mold pathogen by applying a small agar plug removed from the leading edge of an expanding white mold colony growing on potato dextrose agar. The mini-agar plug was extracted using a dental amalgamator. Peas were inoculated with the mycelial plug at the 4th node immediately adjacent to the stem. The inoculated plants were then placed in a humidity chamber maintained at 20 to 25ºC and 100% RH for three days. Of the pea lines screened, 5, 26, 77, 109, 91, and 197 accessions had lesion expansions between, 0 to 1, 1.1 to 2.0, 2.1 to 3.0, 3.1 to 4, 4.1 to 5, and > 5 cm, respectively. Not a single Pisum line was immune to the white mold isolate used to screen the pea lines. Of the 504 lines screened, 210 lines did not survive two weeks post-inoculation. Pea accessions with resistance to white mold based on the restriction of lesion expansion on the stem were identified.