Is it Too Early to Plant Corn?
March 23, 2012 by Bob Berkevich
Is it Too Early to Plant Corn?
Record high temperatures for the upper Midwest have many farmers eager to get into the field. Figure 1 shows that high temperatures have been 25°F above normal. When traveling through central Illinois on Wednesday, March 21st, I drove past numerous fields with tillage and ammonia applications well underway. There were a few corn planters rolling, but it looked as though most were still in the shed. Although conditions might be favorable to planting now, there are some risks that need to be remembered.
Although warm temperatures have led to ideal planting conditions in some areas at this time, we all know that the weather in April could turn cold, wet, and unfavorable for the development of young corn plants. These conditions can lead to uneven emergence, slow growth, and increased pressure from seedling diseases. The growing point of the corn plant remains below the soil surface until about the V4-V5 stage and the plant can recover from a frost. However a few days in a row of a hard freeze in the mid-twenties can kill or severely stunt a corn plant even if the growing point is still underground. Figures 2 shows the average date of the last spring frost in Wisconsin and Figure 3 shows areas of Minnesota when there is a 10% chance of 32°F or lower.
On average, the highest corn yields are achieved with a late-April or early-May planting date in the Northern Corn Belt. As planting is delayed beyond the middle of May, yields typically decline. Most planting date studies do not include March planting dates because conditions are usually not conducive to field operations, even in small-plot university research locations. Figure 4 shows average yield response to corn planting date in Minnesota and Wisconsin. Notice that the Wisconsin chart shows lower yields are typically seen with early planting.
Corn fields planted before the accepted earliest planting date may affect crop insurance payments if replant is necessary. The crop will likely still be insurable against losses later in the season, but contact your crop insurance agent to be sure about the possible ramifications of planting early. Also remember that some of the best hybrids in the market are not in an abundant supply situation because of increased corn acres in 2012 and the stressful seed production conditions in many areas in 2011. If replanting is required because of poor stands or a killing frost, it might be difficult to get the same hybrid for replant. It is likely that only second-tier hybrids will be available.
Taking advantage of good planting conditions in late March might prove to be a good decision, but the risks of poor or uneven emergence, stunted growth, seedling diseases, reduced stands, no crop insurance coverage, killing frost, and replanting with second-tier hybrids should be considered before pulling the early planting trigger. If some acres will be planted early, it would be wise to choose a full-season hybrid with good emergence and early vigor characteristics, plant it on a well-drained soil at a higher elevation, and use popup or starter fertilizer. Feel free to contact your Corn Specialist for guidance about the potential risks and rewards of early planting.