2025 - Your Commission at Work

YOUR RESEARCH COMMITTEE AT WORK

TITLE: On-Farm Crop Rotation and Cover Crop Evaluations, and Sweetpotato Clone Evaluations to Manage Guava Root-Knot Nematode

LEADER(S): Jonathan Schultheis, Baker Stickley, AdrienneGorny, , and Craig Yencho 1 1 2 1

IMPACT STATEMENT

The guava root-knot nematode (GRKN; Meloidogyne enterolobii) is a highly pathogenic species of root-knot nematode to sweetpotato and numerous other vegetable and row crops. Several plant disease management tactics can be used to combat this nematode, and while long-term solutions through breeding resistance and short-term solutions through optimized chemical nematicide applications are evaluated, additional management tactics need to be explored. Rotational and cover crop sequences are important to evaluate as non-chemical alternatives to managing M. enterolobii in the field, which may be particularly useful to organic producers. Further, non- or poor-host rotational and cover crops that suppress GRKN populations may reduce the risk of developing resistance in a population of GRKN to chemical nematicides, or of quickly overcoming genetic resistance in the next cultivar of sweetpotato. The results of improved marketable yield when peanuts were used as a rotational crop have been put into practice by the grower-cooperators of the “South” and “North” studies. In 2024, the cooperator planted approximately 36% of their sweetpotato crop behind peanuts. This year, in 2025, the cooperator is planning to plant over 70% of their sweetpotato acres behind peanuts. Additionally, this grower cooperator has cut tobacco out of his sweetpotato rotation based on the results of these studies. The results of the “South” and “North” studies have been shared at several extension and professional meetings: Southeastern Vegetable Expo, MyrtleBeach, SC (2023 and 2024); Regional Sweetpotato meetings in Wilson and Smithfield, NC; National Sweetpotato Collaborators Meetingin New Orleans, LA (2024) and Irving, TX (2025). The results of the “Blue” study were shared at the Annual Meeting of the NC Sweetpotato Commission and will be shared at the American Phytopathological Society meeting in August 2025. In addition, the results were shared face-to-face with all grower cooperators regarding the RKN populations at their field location. Results have been or will be shared for the marketable and galled yields obtained at their respective site.

TITLE: Breeding Resistance to GRKN and SRKN into a New Generation of High Quality, Marketable Sweetpotato Cultivars for NC Growers LEADER(S): G. C. Yencho, K. V. Pecota, J.R. Schultheis, M. Molinari, Z-B. Zeng, A. Gorny, and M. Kudenov 1 1 1 1 1 2 3 COLLABORATORS: Katie Jennings, Allan Thornton, Suzanne Johanningsmeier, Matthew Allan, Brandon Parker,, and Tommy Batts 1 1 4 4 1 5

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