No. 8 Article 7/May 13, 2005

Lessons from an Unusual Planting Season

The good news is that corn planting in Illinois in 2005 has been record-early, with 94% planted by May 8 this year compared with 93% on the same date in 2004. In 2004, 63% of the crop had emerged by May 8, compared with 52% of the crop emerged this year. With the return of warm temperatures this week, much of the rest of the crop will emerge, so we should be getting back on track. In fact, the high temperature at Champaign was 90° on May 10, so it won't be long before the worry shifts from cold and wet to hot and dry. We have enough soil moisture to hold off that worry for a few weeks at least.

The favorable planting progress this year doesn't tell the whole story, unfortunately. There has been a considerable amount of replanting in some places, though we don't expect the replanted acreage to be much larger than it has been in some other recent years. The main reason for replanting in east-central Illinois has been soil crusting, and the crop that was planted about 3 weeks ago, just before the heavy rainfall around April 20, has had a difficult time emerging. The rotary hoe has been widely used in this area but hasn't always been enough to get adequate stands. Corn planted 2 weeks ago is emerging about as quickly as corn planted 3 weeks ago, and it looks much more uniform, though we don't think that the slow and somewhat uneven emergence in some fields will have serious consequences for yield, as long as the final stand is adequate.

The damage caused by the low temperatures of the last week of April and the first few days of May has been the big story of this planting season, and while most decisions regarding replanting have already been made, it's useful to examine what happened and whether this means we should change our approach another year.

Here is a summary of information regarding freeze injury to corn in 2005:

Soybean planting was already well ahead of the pace in 2004 at the end of last week and is proceeding rapidly this week. Any concern about planting soybean seed into cold soil has evaporated, but the challenge that could come from heavy rainfall after planting remains. Some of the crop may also be planted this week into soils too dry to ensure emergence, so the quandary about whether to plant before or after an expected rain will affect some. It's more or less a coin toss, in large part because "expected" rains sometimes don't arrive on time or in the expected amount. If we knew that a gentle inch of warm rain would fall on a dry field just after planting, then we should probably plant. In reality, we have to weigh chances of not getting a stand because of heavy rainfall against the fact that our optimum planting window extends for a week or two yet in Illinois and against the cost of seed if we need to replant.

Wheat has not been damaged to any extent by the low temperatures over recent weeks, but its development has been delayed to slightly behind average. Dry weather is favorable in terms of limiting development of diseases, including Fusarium head scab, and in providing the sunlight the crop needs for best yields. On the other hand, the crop needs 6 to 8 inches of water to fill grain, so some rain is helpful. Our rule of thumb is that maturity follows heading by about 6 weeks. That would put harvest time close to normal, which will be a week or more later than in 2004. This will be speeded up if the weather turns warm but at the cost of some yield potential.--Emerson Nafziger

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