Heat Stress

As we get into the second week of August, we have experienced some higher-than-normal temperatures and low precipitation in the South Central Iowa trade territory. I don’t believe we’ve lost a lot of potential but must think we have taken some top end of this corn off. In the tougher areas of the field, we definitely are seeing the adverse effects of this high heat. Last week was the first time I really noticed the soybeans starting to turn their leaves over. August is going to need to bring a couple of rains to keep the soybeans going to reach their potential. I’m afraid that pod abortion is going to start happening as well as not quite as big of test weights on corn.

I was evaluating high population corn tests early last week and the weather was having some real negative effects on the extremely high population. I saw areas of 2-3 inch tip back, but this was in a test strip that was higher than 40,000 plant population. That high of population is not normal for our area so don’t expect to see 2-3 inch tip back everywhere. Overall the corn kernels pollinated well and I have seen large kernel counts but this lack of rainfall is going to have an affect on test weight. We haven’t stalled out completely but without any August rain I can’t see us seeing many test weights in the 60lbs area.

On soybeans I felt we had a really good potential going into August. I don’t mind a dry July on soybeans because beans seem to perform under early dry conditions. We aren’t too late for soybeans yet but are going to need a rain or two in August. Right now soybeans are aborting pods as they always produce more than they can handle, but with the hot and dry conditions we know that the pod abortion is higher. Products like fungicide will help alleviate the stress and keep those pods on the plant. Once a pod is aborted it can’t come back unless the soybean produces more flowers on the top of the plant. With late maturity soybeans and late August rains we can get more flowers put on. The biggest thing we can do now is spray a fungicide if we haven’t and hope for the rain to come.