A sustainable approach for weed and insect management in sweetpotato: breeding for weed and insect tolerant/resistant clones

Authors: Wadl, Phillip; CAMPBELL, HARRISON - Clemson University; Rutter, William; Williams, Livy; MURPHEY, VICTORIA - Clemson University; CULBREATH, JULIANNA - US Department Of Agriculture (USDA); CUTULLE, MATTHEW - Clemson University

Submitted to: Weed Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/12/2022
Publication Date: 1/3/2023
Citation: Wadl, P.A., Campbell, H.T., Rutter, W.B., Williams III, L.H., Murphey, V., Culbreath, J., Cutulle, M. 2023. A sustainable approach for weed and insect management in sweetpotato: breeding for weed and insect tolerant/resistant clones. Weed Technology. 37(1):60-66. https://doi.org/10.1017/wet.2022.99.
DOI: https://doi.org/10.1017/wet.2022.99

Interpretive Summary: Management of weeds and insect pests are of concern to sweetpotato growers and control options are limited. The predominant cultivars grown in the United States have been shown to have severely reduced yields under weedy conditions. Herbicide options are limited, and the increasing frequency of large rainfall events can leach herbicide treatments from the soil rendering them ineffective when needed most. Host tolerance/resistance to weeds and insect pests offer an effective sustainable solution to these challenges facing sweetpotato producers but are currently unavailable. In the current study, researchers at the USDA and Clemson University investigated the effects of weed-free interval and sweetpotato clone on weed counts for naturally occurring weed species, storage root yield, and insect resistance to the major pests of sweetpotato. Our results indicate that breeding for cultivars and/or germplasm that are competitive with weed interference and resistant to the major insect pests of sweetpotato offers promise. In the study we identified two sweetpotato clones, USDA-17-037 and USDA-17-077, that had the lowest weed counts, exhibited broad insect resistance, and were the highest yielding entries. The results of this study indicate that development of sweetpotato cultivars that are competitive with weed interference through novel plant architecture (erect growth habit) and are also resistant to insects is an effective general pest management strategy, with particular benefit for organic and sustainable growers.

Technical Abstract: Weed management is consistently ranked among the top priorities of the United States sweetpotato industry. To provide additional weed and insect management strategies for sweetpotato, we initiated development of insect resistant germplasm that also has weed tolerance by breeding and selecting for sweetpotato clones that are fast growing and have semi-erect to erect canopy architecture. Field studies were conducted in 2018 and 2019 in Charleston, South Carolina, USA to quantify the effects of weed-free interval and sweetpotato clone on weed counts for naturally occurring weed species, storage root yield, and insect resistance to the major pests of sweetpotato. Weed-free intervals included plots that were weedy all season and weed-free for 2, 3, and 4 weeks after transplanting. Sweetpotato clones evaluated included ‘Beauregard’, ‘Covington’, ‘Monaco’ and six advanced selections with semi-erect to erect plant habit. Significant weed-free interval and sweetpotato clone main effects were observed for all variables measured, but not for their interaction. Two sweetpotato clones, USDA-17-037 and USDA-17-077, were consistent across both years and had the lowest weed counts, exhibited enhanced insect resistance, and were the highest yielding entries. These results demonstrate the potential for development of insect resistant sweetpotato germplasm with a vigorous, erect plant habit may be less susceptible to weed interference than cultivars with spreading shoot growth. The combination of germplasm that is both resistant to insect pests and competitive with weeds can provide organic and subsistence sweetpotato growers solutions to these critical issues related to sweetpotato production.