Monday, December 11, 2006 - 8:35 AM

Impact of cover cropping on western corn rootworm (Diabrotica virgifera virgifera Le Conte) damage on the Western High Plains

Holly N. Davis, holly3@ksu.edu1, Larry Buschman, lbuschma@ksu.edu2, Randy Currie, rscurrie@ksu.edu2, and Phil Sloderbeck, psloderb@ksu.edu2. (1) Kansas State University, Entomology, 123 West Waters Hall, Manhattan, KS, (2) Kansas State University Southwest Research-Extension Center, Entomology, 4500 East Mary Street, Garden City, KS

The effect of a winter cover crop, Bromus tectorum L., on western corn rootworm damage to corn was studied during the growing seasons of 2005 and 2006. There were two trials, each with three experimental factors: two levels of irrigation, two levels of Bromus, and two levels of herbicide treatment. The plots were arranged in a randomized complete block design with Bromus and herbicide treatments split on the water treatments. The first trial (South) was first planted to corn in 2004, while the second (North) was first planted to corn in 2005. In each plot four plants were dug, the roots washed, and the rootworm feeding damage was rated using the Iowa State 1-3 damage scale. In the South trial there was a mean damage rating of 0.27 in 2005, and 0.86 in 2006. In the North trial there was a mean damage rating of 0.12 in 2006. Plots with Bromus had lower damage ratings (0.19) than plots without Bromus (0.35) in 2005, but the difference was not significant. The following year the Bromus and non-Bromus plots were very similar, 0.87 versus 0.85. However, in 2006 the North trial mean damage rating for the Bromus plots was significantly higher (0.15) than plots without Bromus (0.09). This lack of consistency in the trends suggests that the use of a cover crop did not significantly alter damage ratings from corn rootworms.

Species 1: Coleoptera Chrysomelidae Diabrotica virgifera virgifera (western corn rootworm)