Despite high heat, low rainfall, corn growth stays on track

Due to the lethal nature of heat on all-important corn pollination, temperatures reaching triple digits in some parts of the state have farmers worried. However, a combination of later planting this year and manageable temperatures at night leave some room for optimism.

Dave Ellens, a member of the South Dakota Corn Growers Association, checks on one of his corn plants. His field began silking early last week.
Jason Harward / Forum News Service
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MADISON, S.D. — Despite a July characterized by temperatures over 90 degrees statewide, researchers and farmers say the nature of the heat and a pattern of just-in-time rain should be enough to keep corn pollination on track for profitable yields in the fall. Still, a continuation of the hot, dry conditions this midsummer could start to deteriorate crops in pollination and grain development.

“Some days this week, you could tell the plant was getting stressed,” Dave Ellens, a corn and soybean farmer near Madison, told Forum News Service on Thursday, July 21. “But temperatures have dropped just enough during the nights and mornings that they seem to perk back up.”

The magic number for farmers with corn crops entering the tasseling stage, according to South Dakota State Extension Agronomist Jonathan Kleinjan, is 95 degrees. Any sustained temperatures above that, especially without a substantial drop in temperature at night, can kill the plant’s pollen, negatively affecting grain development and, eventually, yield.

“I don't think the hot dry weather has hurt us to a significant portion yet. I mean, obviously that's based a little bit on geographic area. Some areas are going to be dryer than others, but I would say as a whole so far we haven't really been hurt.

But for farmers counting on the short period of pollination for a high-yield crop with even kernels, sustained high temperatures near the level of damaging pollen output are worrying.


“The worst part about the pollination issues with the heat is that you don’t really know how it’s affecting your corn crop until you can look at that ear and notice how it’s filling,” said Austin Gross, a farmer based just north of Pierre, which saw three days above 95 degrees earlier this week, with a high of 107 on Monday, July 18. “The rest of your weather could be fantastic, and because the pollination window had adverse conditions, in the past, I’ve seen 100 bushel corn crop turn into 20. It definitely happened to our area numerous times in the past.”

Luckily, the delayed planting season this past spring due to some concern over low soil temperature means most of the corn statewide has yet to silk; with forecasts showing a reduction from the high heat over the past two weeks, it’s possible the potentially damaging highs just missed the bulk of pollination.

According to the July 18 Crop Progress Report , the most recent issue of the weekly nationwide survey released by the Department of Agriculture, just 13% of corn statewide has begun silking, all of which occurred in the week ending July 17. At this time last year, that number was 24%.

That doesn’t mean, however, that corn plants statewide have completely avoided damage. A combination of scarce rain and intense heat did leave a mark on the Crop Progress Report, which, despite being a subjective survey, is the best resource for measuring crop health at this point in the growth cycle. Compared to the July 11 report, topsoil moisture conditions had deteriorated from 77% in the adequate and surplus category to 66%.

For the past month, Ellens says his crops have been living “rain to rain,” with about a half inch of precipitation this past weekend and the expectation of around that much this coming weekend or early next week as well.

While Kleinjan says rainfall takes on more importance during the coming grain fill period, the lack of moisture has had a small impact on the quality of crops. The July 11 Crop Progress Report measured 74% of corn statewide in good or excellent condition; one week later, that number was 68 percent.

“If that number goes down, that means we’re drying out,” Kleinjan said. “It's not to say that that number can't can't level off, but I don't really know that I've ever seen it come back up.”

Sen. Julie Frye-Mueller, of Rapid City, is on her way toward reinstatement in the Senate as early as tomorrow, along with censure and "limited" access to LRC.

Jason Harward is a Report for America corps reporter who writes about state politics in South Dakota. Contact him at 605-301-0496 or

Jason Harward covers South Dakota news for Forum News Service. Email him at
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