Prioritize Corn Fields for Harvest

Identifying fields that have standability, disease, stress, uneven maturity, or moisture content issues will help increase efficiency during harvest and minimize in-field losses.

Relative maturity and planting date can help estimate harvest time. Field history, crop rotation, the type of stress (environmental, pest, nutrient leaching, and others) can help predict which fields may have uneven maturity or fields that will need to be harvested early. With that information, you can do a pre-harvest survey of fields to find other issues that may require early harvesting to avoid harvest losses.

Consider monitoring corn for stalk quality as soon as black layer (physiological maturity) occurs. Scout different areas of the field and use the push or pinch tests to identify weak stalks. Split lower portions of stalks to assess stalk strength and determine if the stalks are discolored, shredded, or hollow. Also, inspect ears for rots and test ear shanks for weakness and potential ear drop.

Push or Pinch Test. Scout fields periodically after pollination to check for stalk rot and lodging issues. Walk a zigzag pattern through the field and test stalk firmness by squeezing or pinching each stalk at one of the lowest nodes above the brace roots. Healthy stalks are firm and cannot be compressed. If a stalk feels soft, it is likely prone to lodging. Check at least 100 plants per field.

A second method for determining potential stalk lodging is to push each stalk about 5 to 8 inches from upright (approximately a 45° angle) and note whether the plant springs back, remains tilted, or breaks.

If more than10% of the stalks in a field are rotted or prone to lodging, consider scheduling the field for early harvest. In severe instances, it may be more economical to harvest early and dry the grain post-harvest as opposed to accepting significant losses.

Grain moisture content should start to be monitored soon after physiological maturity (black layer). Shoot for a harvest moisture content level that balances harvest losses and grain drying costs. A plan to take advantage of a rapid drydown and allow everything to field dry could be costly. Harvesting at lower moistures can increase mechanical losses due to ear drop, stalk lodging, and kernel shattering. Consider beginning harvest when corn grain moisture content is a little above 25% so that harvesting can be finished before corn dries completely in the field.1

Sources: 1 McNeill, S. and Montross, M. Corn harvesting, handling, drying, and storage. Pages 52-58. University of Kentucky Extension. http://www.ca.uky.edu. Web sources verified 08/16/2018. 180813225958