The temperature is in the low 80s. Humidity is relatively high, say 50% to 60%. Winds are calm and it’s 9 a.m. If tassels are shedding and silks are set to receive pollen, it’s a perfect situation for picture-perfect corn pollination. That means kernels should form to the very tip of the ear, with no or very few blank spaces in between.
That’s how Dave Nanda describes perfect pollination. It’s likely already happened on your farm this year, but it’s not too late to learn how to appreciate how intricate pollination is when it occurs correctly. Nanda, Indianapolis, is an independent crops consultant. Corn Watch ’17 is sponsored by Seed Genetics-Direct.
Tassels ready to shed
During the morning hours, unless it’s raining, tassels release anthers, or sacks filled with pollen. One pollen grain must pollinate each silk to form a kernel. Normally, there’s far more pollen produced by one tassel than it takes to pollinate a plant. Nanda says it’s part of nature’s safety blanket to make sure each plant can make as many kernels as possible.
“Remember that the goal of a corn plant is to make as many babies as possible,” Nanda says. “The plant doesn’t care about what yield you want. It thinks it’s making babies, and it wants as many progeny as possible.”
Fortunately, the more “babies,” or kernels, it produces, the more yield you get, Nanda observes.
Tassels don’t just open up at random, he notes. Pollen release starts in the middle of the center stem of the tassel first, and then moves up and down the center spike. From there it moves to the next spike outward in each direction until all spikes have opened up.
“You can tell if there will be more pollen released or if pollen shed is over by examining a few tassels,” Nanda says. “If anthers are out and hanging on or have already dropped, there is no more pollen left to release from that section of the tassel. If most of them are open across the entire tassel, but there are a few still closed, then you might have a day or so of pollen shed left to go.”
Silks ready to receive
Timing is everything in baseball. If the batter swings and the ball is ahead of or already past him, he will strike out. Likewise, in corn pollination, if silks are delayed and pollen has already been released before the silks were ready to receive it, pollination won’t be successful. For that ear, at least, it will be like a strikeout.
Fortunately, in the Corn Watch ’17 field and many other fields pollinating in mid-July, pollen and silks were there at the same time. That means a maximum number of kernels should have been fertilized, Nanda says.
Things like corn rootworm or Japanese beetles clipping silks can mess up the timing. Silks can regrow, but it takes a certain amount of time. Fortunately, Nanda observed minimal insect activity in the Corn Watch ’17 field at pollination.
Suppose every possible kernel pollinates all the way to the tip. If the weather cooperates after that point, long ears filled all the way out should add to more “babies” and more yield. If it turns dry or some other stress occurs, the plant may decide it can’t make all the kernels that have been pollinated and begin aborting from the tip back. It will stop aborting when it thinks it’s reached the maximum number of kernels it can fill.
Check out the slideshow for a closer look at the pollination process.