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Title: EFFECTS OF A KILLED-COVER CROP MULCH ON SOIL INSECT PESTS OF SWEETPOTATOES

Author
item Jackson, D
item Harrison Jr, Howard

Submitted to: HortScience
Publication Type: Abstract Only
Publication Acceptance Date: 3/3/2004
Publication Date: 6/20/2004
Citation: Jackson, D.M., Harrison Jr, H.F. 2004. Effects of a killed-cover crop mulch on soil insect pests of sweetpotatoes [abstract]. HortScience 39:668.

Interpretive Summary:

Technical Abstract: One insect-resistant ('Ruddy') and two insect-susceptible ('SC1149-19' and 'Beauregard') sweetpotato genotypes were grown in either conventionally tilled plots (CT) or in a killed-cover crop (KKC) tillage system at the US Vegetable Laboratory, Charleston, SC, in 2002 and 2003. Four-row plots (100 plants per plot) were bedded (102-cm between rows) in the fall of 2001 and 2002. One-half of the plots were planted to a winter cover crop of crimson clover while the other one-half of the plots were left fallow. The conventionally tilled plots were re-bedded before sweetpotato slips were planted. One-half of each 4-row plot was hand-weeded while the other one-half was not. Thus, 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). There were 6 replications in 2002 and 5 replications in 2003. Monocot and dicot weeds were sampled in all plots in mid-season. The CT-WE plots had 10 times as many monocots and 3 times as many dicots as the KCC-WE plots. 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 WDS (Wireworm-Diabrotica-Systena complex), sweetpotato flea beetles, grubs, and sweetpotato weevils 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. Also, injury by sweetpotato weevils was significantly less in the weedy than in the hand-weeded plots.