What happens when pollination doesn’t happen correctly?

Corn Illustrated: Slideshow illustrates three cases where something went wrong during pollination.

Pollination wasn’t over by the end of July everywhere in the Corn Belt this year. A wide range of planting dates meant corn pollinated over a much longer period than normal. That meant the window for good conditions needed to ensure good pollination in every field was wider than usual.

What happens if conditions sour before all fields are pollinated? In some situations, most of a field pollinated properly, but an ear here and there didn’t. What can mess up pollination?

A number of things can go wrong, notes Dave Nanda, an independent crops consultant based in Indianapolis. Some are related to weather conditions. Others are caused by insect issues. Still others may result from an unusual situation occurring within the field.

Pollination misfires
Here are three cases where pollination didn’t occur properly. Nanda provides commentary as to what may have gone wrong.

1. Long, green silks may mean silks emerged after pollen was gone. Very long silks may not be a good sign, Nanda says. If all ears have long green silks, the silks in the entire field may not have emerged until after most pollen had already been shed. Weather stress, especially drought stress, can result in delayed silk emergence. Once silks emerge and aren’t pollinated, they continue growing.

In the case shown in the slideshow, most ears in the field pollinated normally, and silks were the normal length and turning brown.

“This plant was on an end row and spaced out from neighbors,” Nanda recalls. “There may not have been lots of pollen left around it when silks came out. There were fertilized kernels on the ear, but many still remained to be fertilized.”

2. Insects clipped silks back very close to the tip of the ear. If silks are clipped back to within one-half inch of the ear tip and are still green, it’s likely insects clipped the silks and are still at work. The result may be lots of blank spots because silks don’t have a chance to catch pollen so fertilization can occur.

In the scenario shown in the slideshow where silks were clipped, the silks are already brown.

“The ear could have pollinated before silks were clipped,” Nanda says. “At any rate, it wouldn’t pay to spray for Japanese beetles or rootworm beetles if you had a field like this because pollination is already over.”

3. Extreme heat and drought can cause pollination failure. Hopefully this is one situation you didn’t find this year. The 2012 season was notorious for pictures like the one in the slideshow. Pollen was gone by the time silks appeared. If very hot weather is compounded by drought, that can provide disastrous results for pollination, Nanda says.

Click through the slideshow below to see the photos.

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