No. 9 Article 3/June 4, 2010

Corn Crop Surges Ahead with Few Problems

In early May we were concerned that the early-planted corn crop would lose its momentum due to cool temperatures and that early planting might not be a great advantage. Except for areas that received excessive rainfall, though, the weather has been very accommodating so far in 2010, and we finished May with growing degree-day accumulations of normal to slightly ahead of normal in Illinois. The corn crop has responded well.

Adding the GDD accumulated in April, much of the state's corn crop has accumulated 500 to 600 GDD by now, depending on planting date, and this means the crop is at or nearing the rapid growth stage that begins when the stem starts to elongate. In our planting date study at Urbana, the corn planted on April 5 is now at growth stage V9 and about 24 inches tall, close to the "standard" knee-high. Corn planted on April 21 is at V6 and 15 inches tall, and that planted on May 10 is at V4 and about 8 inches tall. Our last planting was made on May 28, and as of June 2 it is about to emerge.

Unless the weather pattern, which has returned to wet in many areas, also turns cool, the 600 or so GDD that June usually brings means that we are well on the way to having an early start to pollination in the crop that was planted in the first half of April. Historically, an early start to pollination is beneficial, because the crop canopy develops early and can intercept a lot of sunlight during the long days of June. It also helps when June is on the dry side, both because that helps roots develop better and because it means a lot of sunlight.

In the meantime, except in areas where water has damaged stands, the season so far has been very quiet, with few of the "what now?" questions we had in 2009 and other years with problem starts. One thing that some have noted is the uneven appearance of corn following corn, with color and size differences across the field. Some of this can be traced to spring tillage, lots of residue on or near the surface, and soil conditions at planting. But as the crop reaches V6 or so, look for its appearance to improve rapidly as the growth spurt kicks in and higher soil temperatures help to improve root growth.

It is possible that the unevenness in the crop, especially in corn following corn, might have an effect on yield, but the warm temperatures have helped to relieve this problem, and we expect the crop to recover well. One producer in central Illinois said that he had used starter fertilizer for the first time this year and that the corn following corn was much more uniform as a result. That could turn out to be mostly cosmetic, especially if conditions in June are good, but it might also help yields due to the faster start and better uniformity. One thing is clear: many fields that were planted early look outstanding at this time. That's no guarantee, but it's certainly a comfort after 2009.--Emerson Nafziger

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