News

Pyrethroid-resistant soybean aphids found in west-central Minnesota

 

An integrated pest management specialist says this is the fourth consecutive year of pyrethroid-resistant soybean aphids in Minnesota.

Bruce Potter with the University of Minnesota tells Brownfield resistance to the insecticide was first documented in 2015.

“In 2016, kind of that same area (of) south-central Minnesota.  Then we picked up some stuff in northwest Minnesota.  Last year it was pretty much the western side of the state.  And this year we’re getting some reports out of west-central Minnesota.”

Potter is aware of resistant aphids in other parts of the Upper Midwest, including northern Iowa and the Dakotas.

He urges growers to evaluate insecticide control four to five days after spraying.

“What we see when we have these pyrethroid-resistant populations is even in small plots some plants that have relatively good control, and then some plants where (control) is absolutely horrible.”

Potter says it depends on if the female that started the colony was susceptible or resistant to the insecticide.

“So if you’re making those evaluations, make sure you don’t just do it on the edge of the field.  Get out there a little ways and check around, make sure you don’t have any hot-spots that are getting away from you.”

Potter says a popular alternative to pyrethroid insecticide right now is chlorpyrifos.  He says pyrethroids with a tank mix partner still seem to be working too.