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Agronomy Update: Fall 2020 Questions




With corn harvest soon upon us, it is especially important this year that we spend time scouting our corn fields and prioritizing which fields need to be harvested first and which ones can wait.  In many areas, corn stalk integrity may be compromised from cannibalization of the stalk caused from very dry conditions. In addition, cannibalization of the stalk predisposes the weakened stalk to stalk and crown rots.  Knowing what fields need harvesting first, may save a lot of headaches later.

The procedure that I follow to check fields is to review which fields were planted in “less than ideal conditions” as well as shorter day hybrids and scout them first. I will then walk across a portion of the field and perform Pinch, Push, Shove and Slash tests along the way looking at both green healthy plants and also plants that are yellow/tan and or stunted:

  • Pinch the stalks 4-8” off the soil level. If it collapses, you have a crown or stalk rot, or both.
  • Push the stalks so the top of the plant touches the row across from it. If it buckles under that pressure, odds are you have a stalk rot.
  • Shove a few stalks down the row and see how much pressure it takes to break them. The less pressure it takes to break them, increases the probability of standability issues.
  • Slash or cut the stalk 10-12” above the soil line with a sharp knife down to or through the roots. (Remember to be safe and cut away from yourself.) I generally dig the plant first. The crown and stalk should be a white or creamy color. The photo below shows a healthy stalk and root on the left, whereas, the stalk and root on the right is not healthy. If it is not, that plant has a crown or stalk rot.

corn stalk roots

The more plants that fail these tests, increases the odds that you will need to harvest that field early or move it up in the harvest schedule. Remember that these affected plants will be more susceptible to wind damage, the longer the harvest window gets.

Lastly, I will look at the shank attachment from the corn ear to the stalk. The longer we wait to harvest the more stress we tend to see on this shank. This is especially apparent when we have:

  • Repeated strong or gusty winds that cause the corn ear to swing back and forth
  • Large corn ears that put additional stress on that shank
  • Drought stressed corn tends to have a smaller shank attachment

Having and following a harvest order decreases the likelihood of harvesting down corn, and increases the likelihood of capturing more yield, but also having a safer and less stressful harvest season.


A common question that arises around harvest time is “I am seeing red or purple stalks and/or leaves on my corn plants, what is it? And is it a bad thing?”

To answer the first question, the red or purple coloring on corn leaves is an accumulation of sugars in the leaves and stalks called Anthocyanin. The process of these sugars accumulating in corn leaves and stalks is somewhat similar to leaves on trees starting to change colors in the fall.  The difference being that trees may also produce a pigment which is more yellow. This is a Carotene or a Carotenoid which mainly produces yellows, oranges and some reds. Conversely, tree leaves with high amounts of Anthocyanin and Carotenoids will tend to be orange in color.

orange-red leaf

Is the accumulation of sugars or Anthocyanin a bad thing? In some instances, yes, it can be. I associate seeing red leaves as seeing a red flag and when seeing red leaves shortly after tasseling or early dent stage, that plant is trying to tell you something.

In many instances the “Sink” or ear is not needing the energy or sugar that the leaves are producing, and those leaves are taking that energy or sugar and storing it which causes those leaves to turn red or purple in color. At this stage of the corn plant development, especially if the corn ear is small or lacking kernels, it may point to pollination problems, soil compaction, disease or insect damage. Something is causing those sugars not to be utilized in grain production, hence the red flag.

red flag corn

The only time I do not mind seeing Anthocyanin on a corn plant is right before harvest and that pigment is showing up on a stalk. This is especially a non-issue to me when these fields/plants have large cobs with a high kernel count. In my experience, those fields/plants with red stalks right before harvest tend to have better standability due to those plants not having to cannibalize the leaf tissue or stalk to feed the kernels on the cob.

leaf issues

As always if you have questions regarding this or other Agronomy issues, contact your Dairyland Agronomist.


Dairyland Seed corn and soybean varieties were entered in the 2020 FIRST (Farmers Independent Research of Seed Technologies) trials. Results are starting to come in and can be found on their website at:

Or, if you’d like to receive the results by email, sign up here:

Corteva Technology Use Agreements

All growers with orders for any Corteva Agriscience brand seed product, regardless of crop or trait (including non-GM products) need to have a signed Corteva Technology Use Agreement in place by September 1. Growers should sign the Corteva Technology Use Agreement electronically at Signing electronically is preferable, however, paper copies are available at

Brian Weller
Brian Weller
Western Region
Dan Ritter
Central Region
Branden Furseth
Northern Region
Rod King
Eastern Region
Terry Jones
Eastern Region
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