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Uncommon pest found in southwest Iowa soybeans

An extension agronomist in southwest Iowa has spotted an uncommon pest in soybean fields.

Aaron Saeugling with Iowa State University says Dectes stem borer bores into soybean stalks where it hatches larvae that feed on the vascular tissue of the plant.

“Obviously that is feeding that we don’t appreciate, and so therefore will kill the petiole of the stem. That’s the structure that holds the leaf, and essentially what happens is we see a plant that starts wilting and eventually will die.”

He tells Brownfield there’s not much farmers can do to manage the pest, but it is easy to identify.

“Sometimes you can find the adult form, and they’re noted for having really long antennae, which are longer than the body of the adult insect. And essentially they’ll have black and white stripes on those antennae.”

Saeugling says Dectes stem borer is such an occasional pest that it’s unknown what conditions factor into its presence. 

And he speculates if the insect is in southwest Iowa, it’s likely in southeast Nebraska soybean fields as well.