Submitted to: Plant Disease Management Reports
Publication Type: Research Notes
Publication Acceptance Date: 6/24/2009
Publication Date: 8/18/2009
Citation: Thies, J.A., Jackson, D.M. 2009. Reactions of Regional and Standard Sweetpotato Breeding Lines to Southern Root-knot Nematode Race 3, 2007. Plant Disease Management Reports. 3:V153, Online Journal at http://www.plantmanagementnetwork.org/pub/trial/pdmr/reports/2009/V153.pdf. Interpretive Summary:
Technical Abstract: Sweetpotato breeding lines and cultivars from the 2007 National Sweetpotato Collaborator’s Trial were evaluated for resistance to southern root-knot nematode, Meloidogyne incognita race 3, in a greenhouse test. The experimental design was a randomized complete block with four replicates of five stem cuttings per entry. The cuttings were planted 10-cm apart in a greenhouse bench containing steam-pasteurized soil (2 parts sand : 1 part loamy sand) on 6 Sep. Nematode inoculum was cultured on Rutgers tomato (Solanum lycopersicum) in the greenhouse. Eggs were extracted from tomato roots using 0.5% NaOCl. Each cutting was inoculated with approximately 3,000 M. incognita race 3 eggs at planting. The soil was irrigated as needed. On 2 Nov, the roots of the plants were lifted, washed, and evaluated for root galling and root-knot nematode egg mass production using a 1 to 5 rating system, where 1 = 0 to 3 percent of root system galled or covered with egg masses, 2 = 4 to 25 percent, 3 = 26 to 50 percent, 4 = 51 to 79 percent, and 5 = >80 percent of root system galled or covered with egg masses. Ratings of 1 to 2.9 are considered resistant and ratings of 3.0 to 5.0 susceptible. All check cultivars performed as expected. Six regional lines (L01-29, L99-35, L02-32, W-341, W-375, and Covington) were highly resistant (HR), similar in reaction to Ruddy (HR-Check). Four regional lines (B-94-14, B-63, NC-Japan, and NC-99-573) were susceptible (S), similar in reaction to Beauregard (S-Check).