Tuesday, July 28, 2015

Way Too Early Prediction: Weak Corn Stalks this Fall

Chad Lee, Extension Agronomist, University of Kentucky
Carrie Knott, Extension Agronomist, University of Kentucky

The 2015 growing season has been wetter than normal with reasonable temperatures. Over 80% of the corn crop and over 70% of the soybean crop are rated good to excellent in the most recent USDA crop progress report. This should be a time to celebrate and enjoy the good fortunes to this point.

We could see weak corn stalks this fall. It's still too early to predict, but several factors make me think it could be an issue. Below are reasons why we could have weak stalks

Reasons Why We Could get Weaker Stalks 
  1. The rains may have caused us to lose some fertilizer nitrogen from the soils while keeping yield levels high. Corn short on N will pull from the stalk to build an ear. That will weaken a stalk.
  2. Roots may be small or weak from:
    1.  "Mudding in" fields this spring that lead to some sidewall or surface compaction. The season has been wet enough to help most roots break through, but the restrictions could hurt. 
    2. Saturated fields around late June / early July killed some roots and slowed expansion of others. Those roots will recover some, but may not be as large as we normally like. 
  3. It's a great year for diseases. Fungal diseases can weaken stalks, especially in hybrids that were highly susceptible to diseases. 
  4. This is a great year for yield potential. At this point, we have lacked sunlight but not much else to make great yields. Heavy ears on plants with weaker stalks (from N loss and/or diseases) and smaller roots make for plants that could fall over. 
Reasons Why Stalk Strength will be Strong
  1. Each field was planted with no soil compaction, each hybrid had excellent disease tolerance (or sprayed timely with a fungicide), excellent stalk ratings, and nitrogen was applied late to the fields to minimize N loss. All of these have to work together to keep stalks strong.
Planning Ahead
Hopefully, I am completely wrong about stalk strength problems this fall. Scouting fields for disease problems, nitrogen problems and stalk problems is a really good idea this season. Knowing the integrity of the stalk strength in each field can help with planning and management of this crop through harvest.

Other resources:
Heavy ears and shallow roots at corn harvest August 21, 2013
Reasons to scout corn for stalk strength August 27, 2013

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