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Title: Response of Two Sweet Potato Cultivars to Weed Interference

item Harrison Jr, Howard
item Jackson, D

Submitted to: Crop Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/5/2011
Publication Date: 8/3/2011
Citation: Harrison Jr, H.F., Jackson, D.M. 2011. Response of Two Sweet Potato Cultivars to Weed Interference. Crop Protection. 30:1291-1296.

Interpretive Summary: Weeds severely limit sweetpotato production in the U.S., because herbicides labeled for sweetpotato do not control all of the weed species common in production areas. Unfavorable conditions like rainy periods soon after transplanting may make the alternative weed control measures, e.g., cultivation and hoeing, ineffective causing severe losses due to weed competition. This problem is more serious for organic growers who cannot use synthetic herbicides and are totally dependent on hoeing and cultivation. The objective of this research was to compare the response of two sweetpotato varieties with distinctly different shoot growth habits to weeds competition. Carolina Bunch has an erect growth habit with short vines that form a dense, taller canopy in the early growth stages. The other variety included in the experiment, Beauregard, has long vines and forms a more open, lower growing canopy in the early growth stages. Weed and sweetpotato growth data indicated that Carolina Bunch was more effective at suppressing weed growth and less susceptible to growth reduction by weed interference than was Beauregard. This study demonstrates that varieties with a vigorous, erect growth habit similar to Carolina Bunch can reduce the impact of weed competition on sweetpotato yields in comparison to sweetpotato varieties with the conventional trailing growth habit. Competitive cultivars could be particularly beneficial in organic production systems where losses to weeds are severe.

Technical Abstract: Field experiments were conducted at Charleston, SC to assess the effect of different durations of weed interference on two sweetpotato cultivars with distinctly different shoot growth habits. The cultivars were Beauregard, which has a spreading growth habit, and Carolina Bunch, which has an erect growth habit. Weed interference treatments included control plots that were maintained weed free throughout the growing season and plots that were maintained weed free for 0, 10, 20, and 30 day after transplanting. In general, Carolina Bunch was more tolerant of weed interference than was Beauregard. In two of three years Carolina Bunch storage root yields were higher than Beauregard yields in plots that received no weeding; whereas yields of the two cultivars in weed free plots were not different. Weed interference affected shoot growth to a greater extent than it affected storage root production. Carolina Bunch shoot biomass was greater than Beauregard shoot biomass in plots receiving no weeding and in plots that were maintained weed free for 10 days in all three years. Shoot biomasses of the two cultivars were not different in weed-free plots. Weed shoot biomasses were greater in Beauregard plots than in Carolina Bunch plots in several instances. These results demonstrate that sweetpotato cultivars with vigorous, erect shoot growth (with shorter stems, greater branching, and a denser and taller canopy early in the growing season) may be less susceptible to weed interference than cultivars with spreading shoot growth that is typical of most sweetpoato cultivars.