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Corn pollination problems pop up

How's our corn pollinating? Answering that question right now may be tough without a close inspection with the way things are shaping up in parts of Illinois, one expert says. And, farmers say they're starting to see mounting evidence that this year's crop is going to fall short of its full potential as pollination issues mount.

"I didn't go out early [and plant] in the mud like some did in my area of southeast Nebraska. I checked pollination and was disappointed. The tip of the ear did not pollinate. Even a few kernels that didn't pollinate in the middle section," says Crop Talk senior contributor highyields. "I'm really surprised since this cornfield didn't tassel until after the heat had moved away, and we did catch a nice rain on it."

Though weather conditions weren't the worst during pollination, University of Illinois Extension agronomist Emerson Nafziger says a few specific conditions were just enough to challenge pollinating corn plants to the point where the process was hampered -- not altogether stopped like during last year's drought -- enough that yield potential could have taken a blow. Do you know why?

"While the weather was generally favorable during the peak period of pollination, it was warm during the third week of July, and soil water may have been limiting during this period in some fields. Thus we would expect to see this in the areas with low rainfall in July," Nafziger says. "This is not the lack of silking that we saw in many areas under the drought of 2012. Silks generally emerged well in most fields this year, but tassel emergence was slowed by dry soil conditions in some cases. The warm third week of July was followed by unusually cool weather, with some lows in the upper 40s and lower 50s the last weekend in July."

Those cool temperatures could have caused one of two outcomes: First, they may have been enough to limit the amount of pollen the plants produced, or second, they could have made silks non-receptive, or unable to germinate that pollen. Either way, there are a couple of things to look for if you suspect one of these conditions is present.

"Indications are that scattered kernels from poor pollination are being found at the base of the ear more than at the tip, which might point toward lack of early pollen production and possible loss of silk receptivity," Nafziger says.

Farmers say these issues caused by more recent cool temperatures aren't the only ones that have kept pollination from from reaching its full potential. The opposite end of the spectrum has caused just as many issues, some say.

"Our corn that was trying to pollinate during that hot, dry week is missing some kernels in the lower half. In our area, that was likely nearly half the cornfields. Probably not enough to hurt the yield most places though, since the top half of the ears seem to have pollinated very well," says Marketing Talk veteran contributor hanktbd. "Maybe just a bit less tipback to make up for the missing kernels on the lower ear portion."

There's not a whole lot that can be done about these kinds of interrupted pollination, but that doesn't lessen the importance of getting into the field to get a feel for whether you're facing pollination trouble. For the most part, there's a fairly simple way to determine whether your fields have had trouble pollinating.

"Once silks start to dry, remove husks and shake or pull on silks. Those that detach easily are from fertilized kernels, while those that stay attached are on kernels that have not been fertilized. Silks that emerge more than a week after silks first appeared and seem to be fresh probably emerged after rainfall, and there will typically be little or no pollen available to pollinate these," Nafziger says. "The target is to have around 500 kernels per ear at populations in the lower to mid-30,000 plant population."

If you do find you've had pollination problems -- though nothing can really be done for this year's crop -- it's important to consider them when selecting corn hybrids for the future, Nafziger advises.

"When different hybrids show different degrees of this type of problem, it is often more a matter of timing than genetics; hybrids that silked on a certain date are often affected more than those that silked a day or two later. But if the same hybrid planted on different dates shows the problem, it may be genetic in nature, or possibly related to soils or management," he says. "For example, a better root system that can pull water a little more effectively can make a large difference in pollination success."


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