There it was plain as sight. One leaf in the field I was scouting had ugly holes. With tissue missing and rugged edges, it was obviously caused by insect damage, not by wind or some other cause. The question was whether it was a problem.
That was quickly answered. It was the only leaf that I saw that was affected in the entire area I searched. Whichever insect caused it was obviously a lone wolf. Since this corn is non-GMO. It wasn’t genetic proteins that scared him off. He apparently didn’t have any help.
Now is the time to scout for certain pests in your corn field. According to the general calendar for scouting in the Purdue University Corn & Soybean pocket guide, you can get a handle for which pests should be active at this time of year.
Lone leaf- Did grasshoppers chew this leaf, or some other pest? The only certainty is that no other leaves appeared to be affected, so one damaged leaf became a non-factor.
However, this isn’t a typical year. Many of the insects depend upon heat units for their development. Since heat units are far ahead of normal, thanks to March, in particular, many insects are appearing early, such as corn rootworm underground and Japanese beetles above ground. So you might want to start scouting a little earlier for various pests than you normally would.
Three pests that could be active at this time of year above ground include armyworm, stalk borers, and the first brood of European corn borers. You also want to be on the lookout for corn aphids and Japanese beetles. Western corn rootworm, a problem in northwestern Indiana, normally doesn’t show up until July, but there are already reports, dating back to early June, that this insect was appearing early. Grasshoppers are also active at this time of year.
The field we scouted showed no characteristic signs of corn borer activity. The tell-tale sign for the first brood is shot-0hole feeding in leaves, since the larvae feed through the leaves before they unfurl form the whorl.
Just because you don’t see insects yet don’t mean they won’t show up. Keep scouting!