ReachOut: Fighting The Sugar War

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By Mike Zwingman

By Mike Zwingman

Reducing Stress At Pollination In Corn: Minnesota has its lakes.  Maine its lobster.  West Virginia has coal mines.  Louisianna, swamps.  Nebraska?  We’ve got corn, right?  Row after row of it across the plains. It’s our state identity.  We’re Cornhuskers.  We’re Cornheads.

Except that corn isn’t exactly adapted for our part of the world.  It’s close, but if we’re being scientific about it, it’s Oregon and Colorado that should be laying claim to our favorite crop, with their lower temps (particularly at night) and lower humidity.

Don’t despair though, dear friends.  We have no need to hand off our identity and livelihoods.  Oregon has the ocean after all, and Colorado its mountains, so let’s just hang onto our corn.  Though it may not be perfectly adapted to us, we have adapted well to it and have developed sufficiently the ability to deliver the one factor naturally missing in the corn=Nebraska equation: water.

Oh, you groan, another irrigation article? Well. Yes.

Because irrigation is that important.  But there’s more to this, too.

Corn grows best in altitudes of 75 to 100 feet above sea level.  At those altitudes, summer days are hot, but not sweltering, and nights are cool enough to merit sweaters.  That is corn weather.  Here in Nebraska, we’re sitting  about 1,200 feet above sea level, which makes for warmer days and nights and higher humidity.

And while we’re really good at complaining viciously about our heat (which, by the by, is totally warranted), this is misdirection on our part.  Corn can actually handle most of the heat that Nebraska throws at it.  What makes it suffer most is the drier soils that result from said heat.  If we are able to keep our soil sufficiently moist during periods of heat, our corn is going to be okay.  Very fortunately, that’s exactly what your center pivots are for.

Low soil moisture at this point in the season, when your plants are approaching pollination, can wreak some serious havoc on silks, which, as you know, are vital to kernel development.  Silks have a shockingly high water content—higher than milk, in fact.  Adequate soil moisture allows them to continue to perform even in high heat (prolonged temperatures above 94 degrees).  Below adequate soil moisture, however, will disrupt silk development and performance, causing consequential changes in the Anthesis Silk Interval (ASI), or the “nick,” which is the time between mid-pollen shed and mid-silk.

Below adequate soil moisture will disrupt silk development and performance, causing consequential changes in the Anthesis Silk Interval (ASI), or the “nick,” which is the time between mid-pollen shed and mid-silk.

Below adequate soil moisture will disrupt silk development and performance, causing consequential changes in the Anthesis Silk Interval (ASI), or the “nick,” which is the time between mid-pollen shed and mid-silk.

Put simply, low soil moisture leads to dry silks, which intercept pollen poorly.  Poor pollen interception leads to small kernels and thus, lower yields from your fields.

So what to do?  Two things, one of which you should see coming from a mile away:

1) Irrigate to sufficiency right now.  Laying down enough water to bring your fields to an adequate soil moisture will help you dodge the problem of dry silks.  Doing so right now will later allow you to run your pivots fast, which works well to reduce the temperature in your fields.  Cooling your fields by a mere 5 to 7 degrees will reduce stress on your plants and pave the way for maximum sugar production.  Corn plants are extremely good at capturing light and turning CO2 into sugar: high daytime temperatures reduce their capacity to do this however.  Using your center pivots to cool your fields will provide the best possible conditions for your plants to maximize their sugar production, which is to maximize their kernel size.

2) Apply a Plant Health Treatment (PHT) at tassel.  Cooling your fields by day will reduce the thermal mass in your fields, which will allow them to cool more sufficiently at night.  But Nebraska’s warm summer nights will still promote nighttime respiration in your corn plants, which zaps the sugar reserves that they worked so hard all day to produce.  Applying a PHT will reduce nighttime respiration, allowing your plants to keep their sugars to be put toward kernel development instead.  The fungicide portion of the PHT will also reduce disease pressure.  With lower disease pressure, your plants can put all of their energy into sugar production.Header1

Ultimately, sufficient water will keep your temperatures down and your soil moist, allowing silks to do their best work.  Adding a PHT paves the way post-pollination to the largest possible kernels and highest yield.

But Mike, you say, I see that you’re getting ready to wrap this dandy article up, but you haven’t mentioned humidity yet.  True, my sharp friend.  If we’re going to talk about Nebraska, we’re going to talk about humidity.  It’s about as Nebraskan as corn is.  The truth is your corn doesn’t like it when it gets too high, just like you don’t like it.  The other truth is, unless you’re fixing to bring your corn into the air conditioning, there’s not much we can do about it.

Even as they suffer through our lousy, tropical humidity though, good practices, center pivots, and correct chemical applications such as PHTs go a very long way toward filling the gaps in corn’s adaptation to this part of the world.  So water well, fellow Cornheads, and enjoy another hallmark of our great state: high yields.