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 that 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.

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Meloidogyne enterolobiiis an aggressive root-knot nematode (RKN) species that has emerged as a significant pathogen of sweetpotato in the Southeastern United States.M. enterolobiiis spread primarily through the movement of infected ‘seed’ sweetpotatoes used for propagation. The RKN resistance in commercially grown sweetpotato cultivars has proven ineffective against this nematode. Detecting RKN in sweetpotato by eye is unreliable, and further distinguishingM. enterolobiifrom other RKN species that infect sweetpotato is labor intensive; relying on molecular tests conducted on individual nematodes dissected out of host roots by trained technicians. Here, we have developed a high-throughput survey method to collect skin samples and extract total DNA from batches of sweetpotato storage roots. Combining this method with species-specific PCR assays allowed for quick and sensitive detection ofM. enterolobiiand other RKN species infecting sweetpotatoes. We tested this method using batches of infected storage roots at varying levels ofM. enterolobiiinfection. We also inoculated skin samples with varying numbers of individualM. enterolobiieggs to determine the method’s detection threshold and used this method to conduct surveys for RKN on fresh market sweetpotatoes. Our results show that this method can consistently and reliably detectM. enterolobiiin sweetpotato batches at levels as low as 2 eggs per 10 mL skin sample. This method will be a useful tool to help screen for the presence ofM. enterolobiiin ‘seed’ sweetpotatoes before they are replanted, thereby helping to slow the spread of this nematode toM. enterolobii-free sweetpotato growing operations.