soybean field
FUNGICIDE AND INSECTICIDE: These soybeans were treated with a product containing fungicides, an insecticide and a biological, but not ILeVO. They show minimal signs of insect feeding.

Signs of seed treatment in young soybeans

Soybean Watch: Plants can exhibit signs showing not only that seed treatments were applied, but also which types of treatments were used.

Four varieties were planted in the Soybean Watch ’18 field on May 5. Steve Gauck made his first inspection of the field on May 31. The agronomist could tell where seed treatments were used and where they weren’t based on how the different varieties looked. What he couldn’t tell was whether seed treatments would make any yield difference when the combine runs across the field this fall.

In fact, there won’t be a way to make fair comparisons, Gauck notes. That’s because any yield difference that might be detected could be due to genetic differences between varieties, not necessarily because of seed treatments.

Gauck is a Beck’s sales agronomist based near Greensburg, Ind. The Soybean Watch ’18 field is in central Indiana. The goal is to learn what might be happening in your fields based on what’s occurring or has occurred in the Soybean Watch field. The project is sponsored by Beck’s.

“Overall, soybeans were uniformly at the V2 stage, with plants spread evenly and average population ranging from 100,000 to 125,000 plants per acre,” Gauck says. “The field isn’t perfect, but it’s indicative of many fields this year. This field was no-tilled into cornstalks. It’s been too hot and dry for slug problems which plagued many fields last year.”

Seed treatments
Here is a closer look at what Gauck learned about seed treatments while looking at the field:

Little insect or disease damage. Two of the varieties are from seed treated with a complete seed treatment package, containing fungicides, an insecticide and a biological product, but not ILeVO. “There was very little insect feeding in those beans,” Gauck says. “I didn’t see any signs of disease either.”

• Bean leaf beetle feeding. One variety was treated with ILeVO to help ward off sudden death syndrome, but not with fungicides or insecticides.

“There was evidence of bean leaf beetle feeding on many plants,” Gauck says. “It’s an indication that the insect was present but didn’t affect varieties treated with an insecticide. We would not expect yield loss associated with early insect feeding.”

NO INSECTICIDE TREATMENT: This variety was treated with ILeVO, but not fungicides or insecticides. Steve Gauck found bean leaf beetle feeding on some leaves.

Disease. Gauck dug up one plant from the beans not treated with the all-purpose seed treatment and found that the roots appeared damaged. Unlike every other plant he dug up across all the varieties he checked, it did not have nodules on the roots. “It’s likely a fungal infection since it’s on the roots,” he says.

FUNGAL DISEASE: This seedling shows signs of a fungal infection below ground. Seed was not treated with a fungicide. Similar symptoms above ground would likely have been from herbicide injury.

• Cotyledon discoloration. The variety treated only with ILeVO showed browning on the outside edges of the cotyledons on many seedlings. There was no browning on leaves themselves. It’s sometimes called the “halo effect.”

“That’s a typical response initiated by ILeVO,” Gauck says. “It doesn’t cause any harm or affect yields, but it’s just a reaction in the plant to the chemical applied on the seed.”

COTYLEDONS DISCOLORED: This variety was treated with ILeVO. It can produce browning around the edges of the cotyledons, as shown here. However, Steve Gauck says this doesn’t cause any yield injury.
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