ARS | Publication request: CROP INTERFERENCE AND TOLERANCE IN SWEETPOTATO CLONES TO WEEDS

Submitted to: Pest Control
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 13, 1998
Publication Date: N/A

Interpretive Summary: Sweetpotato herbicides do not control many of the most competitive weeds in sweetpotato growing regions. This necessitates mechanical and hand weeding at a great expense to growers, and yield losses due to weed interference are often high. The research reported here was conducted to evaluate the response of eleven sweetpotato varieties to weeds. The effect tof natural weed infestations on sweetpotato growth was determined in an experiment that was conducted three times in Louisiana and twice in South Carolina. Average sweet potato yield reductions by weeds in comparison to weed-free plots ranged from 13.6% for W-241 to 71% for L87-125. Although the varieties differed in growth habit characteristics, no one characteristic was highly correlated with sensitivity to weed interference. The most important finding of this study was that some sweetpotato genotypes are consistently much less sensitive to weed interference than others. This implies that sweetpotato breeders can develop varieties not sensitive to weed interference and reduce the need for herbicides, tillage and other weed control measures for the crop. Further studies are needed to determine specific characteristics that give sweetpotatoes tolerance to weed interference so breeders can effectively select for tolerance.

Technical Abstract: Field experiments were conducted to assess sweetpotato crop interference and crop tolerance potential to weeds. Analyses included yield, canopy surface area, weed dry weight, sweetpotato canopy dry weight, and ground light interception on eleven clones with architecturally distinct canopies. A two-fold difference in percentage of ground coverage (canopy surface area) was observed among the eleven clones 42 days after planting, and a three-fold difference in canopy dry weight at harvest. Yields of all clones were reduced by weed interference. Yield reductions ranged from 13.6% to 71%. The yields of 'Beauregard', 'Excel', L87-125, 'Regal' and W-274 were reduced to a significantly greater extent when pressured with weeds compared to their weed-free checks than the other six clones. No clone distinguished itself among the others in suppressing weeds as measured by weed dry weight at harvest and percent ground light interception. Canopy surface area did not correlate with total yield. Our results suggest that weed suppression by crop interference is similar among the clones studied, is not easily assayed in general, and crop tolerance varies greatly among clones for yield.