By Clint Thompson
Two bioassays conducted at the University of Georgia (UGA) showed diamide insecticide resistance developing in beet armyworms. How widespread it is remains a mystery, says Stormy Sparks, UGA Cooperative Extension vegetable entomologist.
“That showed up last year. We’re still not sure how widespread it is. We’ve gotten reports from multiple crops, multiple people, multiple insecticides,” Sparks said. “The two bioassays that have been done at UGA; one of them the diamides look intermediate and the other they really were poor. Where we have resistance, it’s strong resistance. We’re still questioning how widespread it is, but it appears to be fairly widespread.”
There has been various reports of control failures in multiple crops. For growers with beet armyworm infestations, the use of diamides like Coragen, Exirel and Harvanta is questionable. If diamides are not effective, producers should switch chemistries.
“In beet armyworm, there’s multiple chemistries that can work on them, but then you get into, we’ve got three chemistries and lose one and now we’re down to two. We’re putting more pressure on those two, and you lose one of those you’re down to one,” Sparks said. “That’s going to be way too much pressure.”