by PAT LYNCH

Ontario's soil has its best tilth/structure in early April. In April, the soil has just thawed out and is still benefiting from thawing and freezing action. Generally, in late April we get the "April showers that bring May flowers." These rains often last for days and destroy soil structure. Often you need only work a field once in mid-April and plant it, whereas in mid-May soil must be worked two or three times to get a good seedbed. Soil is in much better shape in mid-April than mid-May, and that's when we should plant corn.

Each year, growers work quickly to plant early spring grain and alfalfa. Early-planted corn happens at a much slower pace. When you get good planting days in mid May, corn-planting tempo picks up. If corn was planted in April with the same urgency as it is planted in mid-May, Ontario's corn yield should increase and drying costs decrease.

So what are the risks? First is delayed emergence. In 2005, corn was in the ground four weeks or more before it emerged. Today's seed quality and seed protectants allow us to plant corn earlier into colder soils with less fear of poor emergence. For those acres and years when corn does not emerge, the extra cost of replanting is more than offset by the extra yield when replanting is not needed.

In 2005, we saw the effect of cold soils on growth. For years, many did not believe in the effect of soil temperatures on early-planted corn. Corn planted in mid-April into warm soil looked better in June than corn planted just before the snow at the end of April. Next year, if we see a cold front coming in, we probably should wait until it goes through before planting corn.

You may not be a big believer in soil temperatures to determine planting. In 2005, I used the soil thermometer a certain amount, but I'll be using it much more in the future. When we had cold air temperatures in April but the sun was shining, the soil stayed warm. Hours of sunlight are more important than air temperature in mid-April.

In 2005, growers who planted early and used some tillage to help emergence (rotary hoe, cultivator) felt it was worthwhile. This tillage after planting and before emergence reduces some of the early weeds. It may have helped emergence.

This year, some pre-emergent herbicides applied in April didn't work very well. But then neither did many of those applied in mid-May or even early June. Weed control in corn in 2005 was difficult. We should not be counting on certain broadleaf products giving full-season control if applied in April. The exception would be atrazine. Generally, annual grass products applied in April pre-plant or pre-plant-incorporated gave good weed control.

I expect longer season hybrids, planted early, will significantly outyield the shorter season hybrids in 2005. But that is a function of the weather after May 15 and should not affect the decision to plant early in 2006. BF