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Don’t Sweat Singed Soybeans

By Gil Gullickson 

If you thought your Ilevo-treated soybeans looked a bit rougher than normal last spring after you sprayed them with a residual preemergence herbicide, it’s likely they did.

Still, don’t sweat it. So far, industry and university research shows this halo effect of soybeans with brown-tinged cotyledons soon dissipated.

“Under cool and wet conditions, it is common to see that side effect,” says Kiersten Wise, Purdue University Extension plant pathologist. “If you are using preemergence herbicides, it can be a bit worse. Your beans might look beat up for a few days as they emerge.”

However, they quickly grow out of this ugly-duckling phase, she says.

Early on, though, Ilevo can discolor soybean cotyledons in a manner that mimics disease or an abiotic stress like herbicide injury. “When the fungicide is in the plant, it moves to the cotyledons,” says Wise.

The good news is the halo effect goes no further than the plant’s cotyledons.

“When the active ingredient in Ilevo is taken up by the plant, it is a light-sensitive reaction that occurs on the edge of the cotyledons,” says Mike McCarville, Bayer CropScience technical service representative. “There is no sign that the phytotoxicity goes anywhere else. With four years of our testing, there is no negative impact on the halo effect on yield.”

This also coincides with a 2014 university trial near Wanatah in northwestern Indiana funded by the North Central Soybean Research Program and supported by Bayer CropScience. It’s important to note this was just one location and one year, so the results should be interpreted accordingly.

“In that trial we had in Indiana, there was no yield loss,” says Wise.

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