Published on Tuesday, June 07, 2016
As the southernmost agronomist for Beck’s, I’m usually the first one to see which pest(s) will be the worst, and this year is no exception. Although I haven’t seen much disease or insect pressure (up to this point), I have received numerous calls about yellow tops, white spots, or purpling in corn. With that, I thought this would be a perfect opportunity to explain some of these “corn syndromes.”
Rapid Growth Syndrome (Yellow Tops)
This can occur when young corn has had several days of slow growth (cool, cloudy and wet weather) followed by a period of rapid growth from favorable environmental conditions. The leaves in the whorl do not properly unroll which causes the new leaves that are trying to push out to wrap together and begin to bend. This is the same symptomology that some herbicides exhibit, and they’re often blamed for the phenomenon. The reality is it’s more than likely due to environmental challenges. This syndrome causes very minimal yield loss because its localized to that specific plant.
While I don’t receive nearly as many calls about this syndrome, occasionally a seed advisor, dealer, or farmer will see a dull, silvery streak and get curious. This syndrome typically occurs when temperatures drop below 40 degrees on clear, low humidity nights. Radiational cooling causes damage to outer surfaces of corn leaves that are positioned horizontally to the night sky and are not shielded by other leaves. This syndrome does not cause yield loss or any other detrimental effects.
Purple Corn Syndrome
This is a call I expect every year right after we experience a swing from warm to cool temperatures early in the growing season. The corn is most susceptible to this syndrome before the V6 growth stage, but it can happen later in the season as well. The plant spends all day creating photosynthetic sugars, then temperatures begin to fall at night and the metabolism of the plant slows drastically. This ultimately traps those sugars in the leaf tissue, causing a pigment called anthocyanin to form. This results in a purple appearance to the plant but does not cause yield loss. There are other factors that can cause purple corn such as soil compaction, phosphorus deficiency, and poor root growth, but for this article I am only addressing environmental influences.
I hope this article helped explain some of the unusual things you may be seeing in your fields this year. If you have any other questions or concerns don’t hesitate to contact myself, your seed advisor, or dealer.
Author: Austin Scott
Categories: Agronomy, Kentucky, Tennessee
Tags: Beck's Blog, AgTalk, Agronomy, Agronomy Update, Kentucky PFR, Rapid Growth Syndrome, agronomist, Beck's Agronomist, Austin Scott, Kentucky Agronomy, Tennessee Agronomy, Corn Syndromes, Silverleaf Syndrome, Purple Corn Syndrome
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