Submitted to: National Sweetpotato Collaborators Group Progress Report
Publication Type: Abstract Only
Publication Acceptance Date: December 8, 2007
Publication Date: January 19, 2008
Citation: Jackson, D.M., Harrison Jr, H.F. 2008. A conservation tillage system for sweetpotato: effects on pests and beneficial insects. Page 8 In K. Pecota (ed.), National Sweetpotato Collaborators Group Progress Report, 2007. Technical Abstract: In conventional tillage systems, sweetpotatoes are grown on beds formed from bare soil, which can lead to erosion before the expanding root system stabilizes the soil. Conventional tillage systems also favor the establishment of annual weeds until the sweetpotato canopy is fully established. Conservation tillage systems for sweetpotato may help alleviate these problems. Therefore, we grew three genotypes of sweetpotato (Beauregard, Ruddy, and SC1149-19) in either conventionally tilled plots or in a killed-cover crop tillage system at the U. S. Vegetable Laboratory, Charleston, SC, in 2002, 2004. The four tillage treatments were: (1) conventional tillage, hand-weeded (CT-HW), (2) killed-cover crop, hand-weeded (KCC-HW), (3) conventional tillage, weedy (CT-WE), and (4) killed-cover crop, weedy (KCC-WE). In the fall, one-half of the pre-formed beds were planted to a winter cover crop of an oat and crimson clover mixture, while the other one-half of the beds were left fallow then re-bedded before sweetpotato slips were planted. One-half of each 4-row plot (100 plants per plot) was hand-weeded while the other one-half was not. The center-two rows of sweetpotatoes from each plot were harvested, weighed, and rated for insect damage. The insect resistance of Ruddy held up well under the killed-cover crop conditions, and this cultivar had significantly higher percent of clean roots and lower infestations by soil insect pests than the two susceptible genotypes. In general, injury to sweetpotato roots by soil insect pests was significantly lower in the KCC plots than in the CT plots. Pitfall traps and fire ant sampling indicated that more insect predators were present in the killed cover crop plots.