Seed for corn replants may be in short supply
Early field conditions had many producers thinking about planting. The rain last week has slowed field progress. Soil temperatures last week were running in the upper 50's at night to lower 60's during the day. The temperatures were ideal for corn planting. Producers were holding off because of concerns for a return to normal March and early April temperatures that could mean cool periods or even frost that could slow growth or kill emerged plants.
There are several concerns about replanting corn. Seed supply for 2012 is relatively short due to low seed yields last fall. Several companies went to South America to do some winter production. There are concerns that the arrival of the seed from winter production may not be timely for early replant. Secondly, if replant seed is needed, seed for the best hybrids may be in short supply and secondary hybrids may have to be used for replant if seed is available. Thirdly, replant seed can be costly. Some companies charge less than full retail for replant seed, but they might require planting on or after a certain date. Crop insurance may also be an issue.
Data from the University of Missouri Bradford research farm indicates that over a 6 year period from 2003 to 2008 that corn planted in April suffered no yield reduction due to planting date. The data did indicate that on the May 5th planting date that there was a 5% yield reduction. They did not have any earlier planting dates. Data from the University of Illinois indicates that planting in late March or early April has almost never produced higher yields than planting in late April. In 12 trials in Illinois, conducted over the past three years, corn planted in late April has yielded more than corn planted in late March or early April nine times. The average advantage from planning later was about 4 bu/ac. Their results were similar to Missouri's in that after late April, yields tended to decline with further delays. Both sets of data seem to indicate that early planting on the average does not produce higher yields. Weather could have a large influence on the end result but that is difficult to predict at best.
It probably does make sense to prepare fields for planting. Applying an initial round of herbicides early could result in those applications wearing off well before weeds reach peak growth according to Bill Johnson, Purdue Extension Weed Specialist. A setup herbicide treatment is not intended to eliminate weed problems. The reduced rate application deals weeds a blow until they are knocked out with a post-emergence herbicide later. A setup rate is usually one-half to two-thirds the amount of a full-rate residual herbicide application. If you are applying the setup herbicide early, Johnson recommends using a full rate or use some of your residual herbicide with your post-emerge treatment.