I've spent far too much time at my desk this spring and not getting out to see how things are progressing in the countryside. Many of you have faithfully reported, via telephone or e-mail, the insect situation from your respective areas of Illinois, and several people have sent some excellent photographs of insects and the injury they have caused. However, there's nothing like firsthand experience and observation for getting a real feel for current conditions. I have Ria Barrido with GROWMARK in Bloomington and Dale Burmester with Gateway FS in Red Bud to thank for encouraging me to get out of the office and into some fields in southern Illinois. Dale led us to several fields where I could witness some of the pest problems we have discussed in the Bulletin for the past few weeks. |
Both Dale and Omar Koester, Extension unit assistant in crop systems in Randolph County, explained the county wheat variety plot to several people, including me, on Tuesday, May 16. I was able to see the sad state of several of the wheat varieties in the plot as a result of the wheat curl mite and suspected wheat streak mosaic virus. Several of the varieties were significantly stunted, and flag leaves were rolled up tightly. However, although physical differences among varieties were obvious, we have no way of knowing yet what differences, if any, will occur among yields. In fact, the wheat was in such sorry condition that there was some question about whether it would be taken all the way to harvest.
Both Dale and Omar and their colleagues have been dealing with this rarely occurring problem this spring. Some wheat fields have been destroyed, and yield prospects in other infected fields are not good. However, a drive around Randolph County revealed that some wheat fields look pretty good with decent yield prospects. This fall when growers are preparing to plant wheat for the 2001 crop, we will make certain to offer our recommendations for the best way to reduce the possibility of reoccurrence of the mite and the virus next year.
Dale, Ria, and I also visited some cornfields that had been beaten up pretty badly by the southern corn leaf beetle. There was also evidence of injury that had been caused by flea beetles a couple of weeks ago. I finally got to see it all up close and personal. One field had been replanted and treated with one of the pyrethroid insecticides, but the beetles were still working away at the corn seedlings, seemingly not fazed by the insecticide. The injury symptoms ranged from characteristic notching of leaves and stems to completely tattered leaves. Injury to very young seedlings resulted in rows of holes in expanding leaves, resembling billbug injury. A quick glance at a small field on a hillside revealed the serious impact of this pest on the plant populationmany plants had been killed. I came away convinced that we are going to have to deal with this insect pest for some years to come, probably most frequently after mild winters.
Another cornfield nearby had minor infestations of billbugs (nutsedge was plentiful) and grape colaspis (the corn had been planted after clover), and symptoms of injury caused by southern corn leaf beetles were obvious. In yet another field, we found some evidence of injury caused by white grubs. The white grubs we found were not "true" white grubs in the genus Phyllophaga; they resembled Japanese beetle larvae, although I have not had them identified by an expert yet.
You folks have been right on top of some of our early-season insect problems this year. We sincerely appreciate your reports to us and your willingness to work with growers to protect their crops, if necessary, or to ward off unnecessary insecticide applications when treatments don't make sense. And a special thanks to Dale Burmester and Ria Barrido for their willingness to take time from their schedules to spend time showing me some of the problems growers in southwestern Illinois have experienced this year. Seeing is believing, and you made a believer out of me.--Kevin Steffey