The vast majority of corn has long ago completed pollination. There are the late-planted fields that have yet to do so. Those are the fields that potentially act as a “trap crop” for various insect pests as they look for their main protein source…pollen. One particular insect, known by some producers as silk beetles, is the western corn rootworm beetle. In previous years, this was the time for the peak number of beetles present in the state. In fact, for research trials we deliberately plant corn late the year before in an attempt to lure pollen-feeding female beetles into the crop so there will be plenty of eggs in second year corn. However, beetle numbers are much lower than they once were in general. Still, it is worth a look to see whether rootworm protection (typically a Bt corn hybrid) is a worthwhile option for your operation.
Western corn rootworm beetles feeding on lambsquarters pollen within a soybean field. (Photo Credit: John Obermeyer)
Western corn rootworm beetle engorging on corn pollen. (Photo Credit: John Obermeyer)
It goes without saying, fewer beetles will lay fewer eggs. Of course, the only way to know risk for next year, is to assess rootworm beetle populations NOW, on a field-by-field basis. Unlike some other pest insects, rootworm beetles do a lot of feeding as adults. Rootworm beetles, are pollen feeders, and while corn pollen may be a staple, it’s far from the only food source. So, whether in weedy soybean or wheat stubble fields, pollen from a multitude of weeds (e.g., foxtail, volunteer corn, ragweed, lambs-quarters, pigweed, mustards, etc.) will draw them in to feed. These too are “trap crops” and will likely encourage significant egg laying for next year’s corn roots leading to unexpected lodging. In other words, another reason to keep weed control in mind. Especially if one wants to plant corn without Bt-rootworm traits.
Happy scouting!
