Assessing corn growth and development for yield potential during drought

Southwest Michigan shares corn belt drought conditions while farms search for yield estimates

Corn researchers have used the following estimates for assessing yield reductions during droughts.

Effects of Drought on Corn Yield

Corn stage of development

percent yield reduction from four consecutive days of visible wilting

Early vegetative


Tassel emergence


Silk emergence, pollen shedding






Source: Classen, M.M. & R.H. Shaw. Water deficit effects on corn. Agron. J. 62:652-655. 1970.

Peter Tomison, Ohio State University, states in a recent article that stress is defined as leaf rolling throughout much of the day, and pineapple type plants in southwest Michigan would fit this category this year.

Unfortunately Southwest Michigan is more like the major corn belt this year than the rest of our own state for drought conditions of 2012. Indiana is claiming to be the worst of the worst so far. Their corn is ahead of Southwest Michigan for development and there is much we can learn from Purdue, especially Dr. Bob Nielson, who has been a respected source of corn information for years. Through his information, I’ve located several items that are relevant to Southwest Michigan. When it comes to corn’s response to drought it really doesn’t matter which corn belt state we visit, growth and development are the same, so I’ve tried to find some of the most succinct items to pass along.

Dr. Nielson stated in a recorded interview that corn has passed through several stages and each stage has a response to stress. First, much crop was planted into dry conditions and emergence was spotty, resulting stands will not be at full yield potential. Second, vegetative growth stages are when the ear size is determined. Pollination generally occurs over about 7 days and Nielson stated that there can be a 10 percent per day yield loss when plants are stressed at this time. Nielsen discusses the vegetative stage of corn and resulting impacts of stress in his article, Hot & Dry; More of the Same Not Good for Corn Yield.

The next big hurdle is pollination. Dry weather hastens the pollen shed and slows the emergence of silks, leading to reductions in kernel set. For a visual description of how to assess pollination, watch this quick video by Nielson on the ear shake test to determine corn pollination progress.

If you need a memory refresher on corn grow stages, this interactive chart will help you.

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