The Slow Dry Down of the 2017 Grain Corn Crop

October has arrived and Manitoba grain corn farmers are anxious to start harvesting their 2017 crop. Minimal acres have been harvested (as of October 5, 2017), and fields that have reached maturity are slow in drying down due to cool and rain weather over the past few weeks.

What are normal dry down rates in corn? The best dry down rates are in September. Under good weather conditions from the mid to end of September, dry down rates can vary from 0.75 to 1.0% per day (can be greater in some cases when conditions are warm, sunny and dry, or zero on cool, rainy days!). Into early October, dry down ranges from 0.5% to 0.75% per day. In late October, dry down rate will decrease to less than 0.33% per day. And into November, dry down rate will further decrease to 0.15% per day to negligible amounts.

It is important to keep in mind that moisture loss for any particular day may be higher or lower depending on the temperature, relative humidity, sunshine, wind or rain conditions that day.

Potential Yield Loss. If the crop remains standing in the field, there is the potential for yield loss. The extent of loss will depend on many factors, including stalk strength, ear drop or wildlife damage. Ear drop will vary by hybrid and environmental conditions as well as the amount of grain on the ear (smaller ears should stay attached better than larger ears).  Stalk strength should also be considered when evaluating harvest timing (and this includes assessments of stalk rots). Compromised stalk strength could lead to increased stalk breakage, resulting in lost yield.

As corn matures and dries down, it will be a more common sight across Manitoba in the coming weeks to see farmers harvesting their grain corn.

Originally Posted on Crop Chatter in November 2016
Last Revised October 2017