A Multifaceted Approach to Production Methods and Pest Management in Organic Sweet Potato Systems
Project Director
Katie Jennings
Year Funded
2019
Award Number
2019-51300-30247
Funded Institution
North Carolina State University
Grant Program
OREI (Organic Agriculture Research and Extension Initiative)
USDA NIFA Report (alternate)
Project Overview
This project developed recommendations for organic production of sweet potatoes, including soil health, crop nutrition, and integrated pest management (IPM). Research focused on weed management, as growers identified weeds as the leading challenge in organic sweet potato production.
Field studies in NC, MS, AR, and IN evaluated the effects of cultivar, transplant spacing and stem orientation, timing of mechanical weed control, and cover crops on sweet potato yield, size grade, and weed pressure. Additional studies explored varietal differences in allelopathic potential against weeds and in wireworm resistance, rotation crops to control sweet potato black rot (Ceratocystis fimbriata), and root-feeding nematodes.
Farmer Takeaways
(1) Horizontal stem orientation and an 8” within-row spacing (vs. 12-16”) may improve sweet potato yields and proportion of tubers that grade No. 1 (1.75-3.5” diameter).
(2) Control weeds for 5-6 weeks after planting; uncontrolled weeds can cause 60-100% loss.
(3) Choose locally adapted, weed-suppressive cultivars.
(4) Taller canopy, larger leaves, and allelopathic activity enhance weed-competitiveness, while longer vines do not.
(5) The cultivar ‘Monaco’ is wireworm resistant but less weed-competitive in cooler areas.
(6) Winter cover crops improve soil health without worsening wireworm damage but may not directly improve sweet potato yield by providing N.
(7) Rotate sweet potato with cabbage, peanut, cucurbits, or wheat to control black rot.
Project Outputs
North Carolina Organic Commodities Production Guide – Chapter 8: Sweet Potatoes | NC State Extension
Woodard, A. J., Schultheis, J. R., Jennings, K. M., Woodley, A. L., & Suchoff, D. H. (2024). Horizontal Planting Orientation Can Improve Yield in Organically Grown Sweetpotato.
Cooper, E. G., Meyers, S. L., Arana, J., Jennings, K., Adair, A., Gibson, K. D., & Johnson, W. G. (2024). Evaluation of critical weed-free period for three sweetpotato (Ipomoea batatas) cultivars. Weed Science, 72(3), 267–274.
Cooper, E., Meyers, S. L., Jennings, K., Adair, A., Gibson, K. D., & Johnson, W. G. (2024). Effect of in-row spacing on weed suppression and yield of ‘Covington’ and ‘Monaco’ sweetpotato. Weed Technology, 38, e59.
Werle, I. S., Noguera, M. M., Karaikal, S. K., Carvalho-Moore, P., Kouame, K. B.-J., Lima, G. H. B. de, Roberts, T. L., & Roma-Burgos, N. (2023). Integrating weed-suppressive cultivar and cover crops for weed management in organic sweetpotato production. Weed Science, 71(3), 255–264.
Werle, I. S., Noguera, M. M., Karaikal, S. K., Carvalho-Moore, P., Kouame, K. B.-J., Tseng, T.-M., & Roma-Burgos, N. (2022). Allelopathic potential and competitive traits of sweetpotato cultivars. Frontiers in Agronomy, 4.