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Consider damage vs. disease when planning for 2022 crops

Photos by Tom J. Bechman Steve Gauck holding soybean plant
DAMAGE OR DISEASE? Agronomist Steve Gauck zeroed in on this soybean plant because it had an enlarged lower stem just above ground level.
Soybean Watch: Some plant damage may be a cost of doing business.

Before you close the book on 2021 soybeans, reflect on what you learned and carry those lessons into 2022. If you took notes while scouting fields in 2021, review them. Determine if disease issues popped up this year, and if so, what factors led to these diseases.

“This is a good way to prepare for next season,” says Steve Gauck, a regional agronomy manager for Beck’s, based near Greensburg, Ind. Beck’s sponsors Soybean Watch ’21.

Related: Proof that soybeans compensate for missing plants

“If you know which diseases were present this year, and whether there were other factors that set them up — like weather conditions or plant damage from driving over beans with the sprayer — then you can better determine what to expect in ’22,” Gauck says.

Diseases are almost always weather-dependent, but you know that if some diseases, such as sudden death syndrome, are in a particular field, then the odds of seeing that disease again in the future are higher. Whenever that field goes back to soybeans, it would be a good candidate for varieties with good resistance to SDS, plus SDS seed treatments.

2021 example

This example from the 2021 Soybean Watch field illustrates how sometimes disease is the secondary problem. The plant pictured here stood out to Gauck because the lower part of the stem seemed swollen. He noticed this plant on his final scouting trip of the season in the field.

Once he pulled the plant, Gauck noticed there was obvious damage to the stem about one-third of the way up the plant.

“When I looked down the row where I pulled it, I noticed other plants knocked down, bowed over or missing,” he says. “It was obviously a sprayer track, likely from the fungicide application. There was a matching area a few feet over where the other sprayer tire would have run.”

When Gauck split open the stem, he found black discoloration in the lower part of the plant. The discoloration was from disease. He concluded that this plant was damaged by a sprayer tire, and fungi which caused the disease infection entered the plant through the open wound on the stem. Other plants in nearby rows were healthy, so the cause and effect were obvious.

soybean plant stem split open, showing signs of disease

The black discoloration inside the stem of this soybean plant indicates disease is present, but it likely entered due to stem damage.

“It’s important to know that this was not part of a widespread disease infestation and something you need to worry about in the future,” Gauck says. “Fungi that cause disease are almost always present in the soil. If a plant is damaged and an opening exists, fungi will get in. Most of the time, though, it won’t be a problem.”

So, is driving through the field to apply fungicide and/or insecticide worth it? “Absolutely,” Gauck says. “We noticed in August and in late September that these beans were very clean, with little disease overall, even on bottom leaves in the canopy. The fungicide did its job.”

A few damaged plants where tires run is the “cost of doing business,” he says. He is confident that the benefits of the fungicide and insecticide applications far outweighed minor plant damage.

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