The Indiana Certified Crop Adviser panel includes Betsy Bower, Purdue Extension senior research associate, West Lafayette; Abby Horlacher, Nickel Plate Consulting, Sheridan; Brian Mitchem, Farmer 1st Agronomy Consulting Services, Decatur; and Dan Quinn, Purdue Extension corn specialist, West Lafayette. 

 

One of my cornfields has been hit hard by anthracnose, and the stalk quality is quickly deteriorating. Should I plan an early harvest? How do I determine when to harvest? Will I be compromising yield by going early?

 

Bower: Yes, you should consider an early harvest. Keep monitoring stalk quality by doing the push or pinch test. To do the push test, go into the field past the end or border rows. Push stalks away from you. If 15% to 20% of the stalks lodge easily in 10 to 20 consecutive plants, harvest as soon as the corn hits black layer. The pinch test reveals the same info. To do the pinch test, pinch the base of the stalk from 10 to 20 consecutive plants in a row. If 15% to 20% of the stalks collapse easily, harvest as soon as corn reaches black layer. 

 

Yields can be compromised if you harvest before black layer. However, it may be a decision you need to make to salvage the most grain. If you can wait until 3/4 to 7/8 milk line of the grain, you will capture over 90% of yield. It will be hard to handle the wet grain, and it will take some energy to dry it, but it may be the best decision if you are hit hard from anthracnose, other diseases or anything that kills the corn plant early.

 

Horlacher: Harvest early to decrease the risk of greater loss from lodging or having the corn go flat. This will outweigh any yield loss from early harvest. I would harvest the field once you have black layered and can harvest the grain properly without having grain bridge up in the machine from being too wet. To determine if the field needs an early harvest, walk the field and push on the stalks to see how easily they go down. You can also pinch the lower nodes of the stalk to see if they are firm and healthy or collapse easily under pressure.

 

Mitchem: The “golden glow” of late-season anthracnose is a common sight in many cornfields after Labor Day in my area. Anthracnose affects the top leaves of the plant, and they rapidly turn from green to gold/yellow and then brown over a few days. If this hits before corn reaches black layer, then yield and stalk quality can be impacted. 

 

Most of the time, late anthracnose can cause the stalk above the ear to degrade, but below the ear, the stalk remains solid. If you see the stalk below the ear suffering, then plan for harvest as close to 25% moisture as possible. Waiting for in-field dry down with weak stalks is one windstorm away from a harvest issue. There is always a balance between improved harvestability and drying costs.

 

Quinn: If stalk quality is deteriorating and stalk rots are confirmed, prioritize those specific fields for an earlier harvest. A simple “push test” by walking rows perpendicularly and pushing on them to see how easily they break can be a good indicator of stalk quality prior to harvest. 

 

Harvest should be done after the crop reaches maturity and when the grain moisture falls below 30% and to an acceptable grain moisture for harvest. You will not be compromising yield by harvesting early, but the economic implications will be higher drying costs. However, these higher drying costs often do not surpass the costs and challenges associated with significantly lodged corn.