Considerations During Corn Harvest

October 4, 1999
As corn harvest shifts into high gear over more parts of the state, we are hearing reports of variable yields. The weather in 1999 has certainly caused us to expect a lot of variability, and there is no doubt that the lack of rainfall following pollination has severely hurt yields in some areas. In areas already harvesting, however, a more common comment has been that the yields are better than expected; many have wondered how only a few inches of rain spread across July and August can produce yields that were in some cases higher than normal, and certainly much higher than expected.

One key to better-than-expected yields in some areas in Illinois this year was the favorable temperatures that held during the latter half of the summer. People will tend to remember the summer of 1999 as hot, but a look at the weather records will show that the first half of the summer had temperatures somewhat above average, whereas the last half had temperatures at or below average. This meant that plants used less water than they would have otherwise. This, coupled with the large amount of sunshine and the favorable cool night temperatures that accompany low humidity, led to rapid filling rates. Growing degree-day accumulations were average to above average, and with the early planting in many areas, the crop finished filling by the end of August or early September. To top it off, the very dry weather of September caused very rapid drydown, with the result that many fields were harvested at moistures below 20 percent.

We will also remember 1999 as the year when "GMO" corn and soybeans had everyone's attention, not only because of the news in April that certain genetically modified corn hybrids could not be exported to Europe, but also because of the request by some processors that genetically modified corn and soybean be kept separate when stored. That affected those who delivered to some elevators but not to others. Regardless, it sent an unwelcome message as to what producers might be asked (and not paid) to do in the future. Keeping Roundup-Ready soybeans separate is straightforward, but it is difficult, if not impossible, to clean every last seed from the combine before starting a new field. In corn, the situation is complicated by the fact that pollen from a Bt or LL field that blows into a field of normal corn will produce kernels that will test positive for the presence of the Bt or LL gene. There are also reports that some Bt hybrids, which are cleared for export to Europe, may have some low amounts of RR genes. This means that it will be difficult to be completely sure that no GMO genes are present in the harvested grain of any cornfield. The best we can do, from a practical standpoint, is to harvest the outside 12 or 16 rows from normal fields, especially if they border GMO fields, and feed that grain or put it on the truck marked as GMO. Keeping track of which wagon or truck is which can also be difficult. Some have found a simple marking method, such as different-colored tape for GMO and non-GMO, to be useful. Using fluorescent tape will help these to be visible even at night.

As harvest ends, the questions about what approach to take with the 2000 crop is one that occupies much of our attention. We will consider that more in depth in a later issue of the Bulletin.--Emerson Nafziger

Author: Emerson Nafziger