By Dervin Druist, Syngenta agronomist
Corn is developing quickly this time of year, and agronomists often get questions about nutrient deficiencies, herbicide concerns, and other plant growth related topics. On my recent service calls, I was reminded again of the importance of the root zone. Planting into optimum conditions was difficult this spring, and now the roots are battling the seed zone issues that we created mechanically, or by hydraulic compaction due to the very heavy rainfall we had at times.
Hydraulic surface compaction
As I sank my spade in fields across several states, it was obvious there was significant surface compaction in some areas this year. Many times, the top two inches of soil would come up like chunks of brick. What would you expect the corn plant to look like under those conditions? In one situation, a grower no-till planted at one-inch seed depth this year because he thought he needed quick emergence with the cold, rainy conditions. As we dug up roots in that field, what little root development we noticed on V4 stage corn was all horizontal root growth. You could literally see the roots growing flat. That corn looked to have nutrient deficiencies, but the bigger problem was the root zone. Good root zone growth is at a 30 to 40 degree angle.
Floppy or Rootless Corn Syndrome is another root zone issue that often shows up in the V3-V6 stage. This issue is commonly linked to environmental factors, including windy conditions. Floppy corn often shows up in areas where heavy rainfall or saturated soil conditions were followed immediately by hot, dry conditions. Shallow planted corn or wet planted corn where the seed furrow gasps open is also more prone to the problem. Nodal root growth is temperature sensitive; R.L. (Bob) Nielsen of Purdue University suggests that nodal root growth stops when soil surface temperatures reach 86 degrees Fahrenheit.
Unfortunately, I am seeing lots of “tomahawk” roots so far this spring. We had less than ideal planting conditions, and many growers planted into conditions that created sidewall and mechanical compaction, causing tomahawk roots. If the weather patterns provide adequate moisture, this is less of a factor, but if it becomes droughty and hot, these plants will suffer from the stress more than a properly rooted plant.
Check your corn for root zone issues
Take a strong handled spade (I prefer the fiberglass handled ones; I’ve broken too many wooden ones) and a bucket of water and go dig some roots in the trouble spots in your fields. You may be surprised what you can learn by observing the difference between good root development and the root wars that go on in tough conditions. The corn plant is a resilient fighter, but it can get into situations where the root zone battle can’t be overcome. Happy digging!