Effects of summer cover crop management on wireworm (Coleoptera: Elateridae) abundance and damage to potato

The effects of planting date and mowing interval of the summer cover crop consisting of a sorghum-sudangrass hybrid on the abundance of wireworms, Melanotus communis (Gyllenhal), Conoderus rudis (Brown), C. amplicollis (Gyllenhal), and C. falli Lane, and subsequent damage to tubers in the following potato crop were investigated during two consecutive growing seasons in southern Florida. Eight summer cover crop management programs were evaluated: cover crop planted early (within 38 d after potato harvest) and late (75-89 d after harvest) and mowed at 3-, 6-, or 9-wk intervals; cover crop planted early and not mowed (standard summer management program); and mechanical fallow. In both years, planting date affected wireworm abundance and damage to potato. In the 1st yr, wireworm larvae were 14.2-33.7 and 19-45 times more abundant in plots planted with early cover crop than in those planted with late cover crop and in those fallowed, respectively. Wireworms were 1.3-2.0 times more abundant in plots planted with late cover crop than in plots mechanically fallowed. Similar results were found during the 2nd yr. Mowing interval did not consistently affect wireworm abundance. Wireworm damage to potato tubers was affected by planting date. Percentages of wireworm injury and damage to tubers were 6.6-9.6 and 1.8-6.7 times greater in potatoes that followed early-planted cover crops than in those that followed late-planted cover crops or mechanical fallow in the first and second year, respectively. Crop loss due to wireworms was $1,808-$2,084 and $1,298-$3,386 per hectare higher in plots planted with early cover crop than in those planted with late cover crop in the first and second year, respectively. Thus, delaying the planting date of the summer cover crop resulted in a reduction in wireworm abundance and associated crop loss in the following potato crop.