No. 2 Article 5/April 1, 2005

Gearing Up for Wheat and Corn in 2005


The wheat crop planted in Illinois last fall is estimated at 650,000 acres, the lowest number since record keeping began in 1866. Planting progress last fall was slightly behind normal for the first half of the crop, with about 50% planted by about October 17. Wet weather in October slowed progress after that, and an estimated 20% remained to be planted after the end of October. It's reasonable to assume that some of these acres did not get planted at all, but there was more late-planted wheat in the fall of 2004 than we normally have.

Wet weather continued through January in most places, with temperatures about average. Some damage occurred due to standing water, and growth of the crop was no better than average before it went into dormancy. Most of the crop appears to have survived the winter, and dry weather in March has helped the crop to recover some, though low temperatures have limited the amount of tiller growth. Dry surface soils and moderate temperature fluctuations have perhaps reduced the potential for heaving in most fields, but it may be a problem in some areas. Heaved-out plants can survive and grow back, but the need to grow back most of their root system might compromise their ability to sustain high growth rates, at least temporarily.

Having more tillers develop in the spring is especially critical for late-planted wheat. Using a conservative estimate of 1 bushel of yield for each head per square foot, we think that a normal stand of 25 to 30 plants per square foot needs at least two productive tillers (heads) per plant to have reasonable yield potential. Most early-planted fields have such tiller numbers by now, especially in southern Illinois, where slightly higher temperatures have allowed more spring growth. Late-planted wheat may still need to develop a few more tillers in order to have reasonable yield potential. The amount of spring tillering is mostly determined by the weather, with temperatures in the 50s and 60s and lots of sunshine, best for tiller formation. A sudden onset of temperatures in the 70s will often stop tillering and cause the plant to grow upright and so could reduce yield potential if tiller number is an issue.

Wheat plants will start to take up nitrogen slowly as growth resumes, but there is little actual proof that applying more than normal amounts of nitrogen early to cause more tillers to form can increase head numbers and yields. For most wheat fields in the southern half of Illinois, using a total of 100 to 110 lb N per acre (fall plus spring) should be adequate. Higher organic matter soils in northern Illinois often produce highest yields with 20 to 30 lb less N than that. Splitting spring N into two applications has not been shown to increase yields consistently, though wet weather in April might cause enough N loss that a supplemental application might pay. As a rough guideline, we would not suggest considering supplemental application unless the crop shows N deficiency as it nears heading, and then would suggest no more than 30 to 40 lb of additional N.

Corn: Time to Plant?

Dry weather during March has thoughts turning to corn planting, especially after 2004, when planting started and ended early, and yields were record-high in Illinois. There are a few points to keep in mind as we move into April:

Based on research we have done, we can make a simple statement regarding early April planting of soybean in Illinois: Don't!--Emerson D. Nafziger

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