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Long-term advice for preventing stalk rot

Tom J. Bechman gray leaf spot lesions on corn leaf
PREVENT FOLIAR DISEASES TOO: There is a difference in resistance to gray leaf spot among corn hybrids. Picking more resistant hybrids should lower susceptibility to stalk rots, too.
Corn Illustrated: Here are tips that should minimize problems with stalk rot.

In the past five years, we haven’t seen a near-normal crop season. However, it appears we’re going to have a good year for corn production in most of Corn Belt, even though we had a late start in some areas. Weather experts say 2020 may be as close to normal as we’ve been, in terms of weather events, for some time.

Still, there was too much rain in some areas that delayed planting. Hot and humid weather in early to midsummer was conducive to the development of leaf diseases such as gray leaf spot. These conditions also make plants more susceptible to stalk rot pathogens.

Summer heat and drought in some areas put lots of stress on plants, and caused them to abort tip kernels and cannibalize stalks to meet needs of kernels during grain fill. This is another reason there may be stalk rot problems this fall in some areas.

My advice is to be proactive and do rigorous scouting for stalk rot diseases. Prioritize fields for harvest by conducting stalk pinch or push tests. Premature death, poor grain fill, lower test weight, stalk lodging and ear rots all can reduce yields.

Look ahead

Stalk rot diseases are difficult to control, but there are practices that can help reduce yield loss. Here are some measures that could be effective:

Hybrid selection. This is a very helpful tool in stalk rot prevention. Hybrids with good resistance are available. Hybrids resistant to stalk rot diseases such as diplodia or gibberella may not be resistant to anthracnose. Once diseases such as anthracnose, diplodia, fusarium or gibberella get established in a field, there isn’t a whole lot you can do to stop their spread. Prevention is the best way to control stalk rot pathogens.

Pay attention to resistance to foliar diseases, too. Because severe foliar infection can set up plants for stalk rots, ensuring plant health until harvest includes picking hybrids with good resistance to foliar diseases.

Balanced soil fertility. Balanced nutrition reduces plant stress. Too much nitrogen and not enough potash can make corn susceptible to stress and stalk rot diseases.

Crop rotation and deep tillage. These practices can be very helpful in reducing most stalk rot diseases. Reduced-tillage systems increase the level of disease organisms.

Foliar fungicides. Fungicide application reduces leaf diseases and improves plant health. That may also help reduce stalk rots.

Insect resistance. Picking hybrids with insect-resistant traits or using insecticides, if needed, may also reduce stalk rot.

Plant populations. Some people may want to increase population to increase yield. Do so gradually based on soil fertility levels. Excessive plant populations for the conditions can cause stress and increase risk of stalk rots.

Cover crops. My scientific observations over the years while scouting and comparing hybrids with identical genetics have shown that crops grown after cover crops usually have fewer diseases such as gray leaf spot and northern corn leaf blight, and fewer stalk rots. These pathogens exist as spores in the soil from previous crops. Cover crops can provide an extra layer to “cover up” these organisms.

No, I don’t have data to back up these claims. But scientific observations made over multiple years comparing the same hybrids in fields with and without cover crops carry weight with me.

Nanda is director of genetics for Seed Genetics Direct, Jeffersonville, Ohio. Email [email protected] or call 317-910-9876.

TAGS: Crop Disease
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