By: Dave Pike
Fungal and bacterial infections which often start early in the season will many times show up in corn as late season stalk, ear, and kernel rots. The primary factors that turn an early infection into a serious disease are plant stresses. While dry and hot weather are the typical culprits, any environmental condition that stresses the corn plant will make it more susceptible to rots.
In 2016, a common stress found in much of the Midwest was too much rain and very warm overnight temperatures. Both conditions accelerate plant nighttime respiration and the loss of carbohydrates. The lost carbohydrates are needed for stalk strength and for maintaining the integrity of cell walls which inhibit fungal infection. The warm and wet leaf surfaces also create nearly ideal conditions for a fungal infection to spread within a plant. With a high probability of wet conditions prevailing through the early fall through the Midwest, staying ahead of potential lodging issues and kernel diseases could mean more money in the bank.
When we have had conditions like these, the best course of action for a grower is to walk into a field and do the pinch or push test. Pinching stalks half-way between the ground and the ear or pushing stalks 30 degrees from the vertical to test for brittleness will give a good indication of whether or not early harvest might reduce further losses from lodged plants or premature ear drop. However, in lieu of actually entering all of your fields there are some indicators that might help you know where to look.
Fields planted with susceptible hybrids or at high populations, which result in narrower stalks, are going to be at greater risk. Taller hybrids and those with ears placed higher on the plant are also problematic. This should tell you where to start to look. If you have a drone and have been wondering how you might use it, you could fly it over suspect fields and look for plants that are considerably more mature than other parts of the field. Clue: plants with accelerated maturity are exhibiting stresses that make them more prone to stalk and ear rots.
There isn't anything that can be done this late in the game to correct the problem except to prioritize harvest for fields which show signs of stalk and ear rots. Although moisture content of the grain may be high, an early harvest and appropriate drying can stop the advance of kernel and ear diseases and reduce losses from ears not harvestable.
Tools like Tractor Time and Field Forecast in Morning Farm Report can help growers plan ahead for an early harvest. Tractor Time provides 14 day forecasted soil conditions, allowing growers to avoid compaction or wet spots, while Field Forecast shows field-level forecasts on rainfall, temperature, GDD, and humidity.
If using a drone to scout your fields for signs of stalk, ear, and kernel rots, our free iOS app, Pocket Drone Plan, checks wind speed and direction, visibility, weather conditions, and controlled airspace boundaries so you can be prepared before you fly.