ARS | Publication request: Reactions of Regional and Standard Sweetpotato Breeding Lines to Southern Root-knot Nematode race 3, 2008

Submitted to: Plant Disease Management Reports
Publication Type: Research Notes
Publication Acceptance Date: June 24, 2009
Publication Date: August 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, 2008. Plant Disease Management Reports. 3:V152, Online Journal at http://www.plantmanagementnetwork.org/pub/trial/pdmr/reports/2009/V152.pdf.

Technical Abstract: Sweetpotato breeding lines and cultivars from the 2008 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 of each entry. The cuttings were planted 10-cm apart in a greenhouse bench containing steam-pasteurized soil (2 parts sand : 1 part loamy sand) on 12 Aug. Nematode inoculum was cultured on Polinas 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 on 18 Aug. The soil was irrigated as needed. On 7 Oct, 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% of root system galled or covered with egg masses, 2 = 4 to 25%, 3 = 26 to 50%, 4 = 51 to 79%, and 5 = >80% 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. Five regional cultivar entries (Evangeline, Liberty, Covington, Charleston Scarlet, and Murasaki-29) were highly resistant (HR), similar in reaction to Sumor and Ruddy (HR-Checks). Five regional lines (L02-32, L05-111, B-94-14, B-63, and NC-Japan) were susceptible (S), similar in reaction to Beauregard (S-Check).