As I mentioned in last week's newsletter, grape colaspis has caused some early season stand reduction in cornfields in eastern Iowa. On July 19, I was in Harrison County (western Iowa) and in seven first-year cornfields I found adult colaspis beetles (these beetles may not be grape colaspis). They seemed to be most abundant on the green silks, whereas a few were hidden in the leaf axils. One field southwest of Magnolia averaged at least one beetle per plant.
|Colaspis beetles have been found in corn in western Iowa.
The significance of this information is that if you had poor stands early in the season and were unable to determine the cause, a colaspis may have been one of the reasons. The colaspis beetles may be an emerging pest that becomes more significant to corn production in future years.
This article originally appeared on page 133 of the IC-490(18) -- July 28, 2003 issue.