Worms Already Present in Full and Double Cropped Soybeans

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All signs so far point to this year as being wormier than the previous three. I started picking up yellowstriped armyworms in a light trap last week and there have been soybeans that are starting to show some defoliation- both full season and double cropped. Here are some suggestions:

Scout your fields– no time for blanket sprays for two reasons. 1) Commodity prices dictate that you should pinch pennies where you can and 2) pyrethroid sprays can blow up worms later in the season by killing beneficial insects.

Correctly identify the pest– yellowstriped armyworms and green cloverworms can easily be killed with a pyrethroid. Fall armyworms and soybean loopers require pricier insecticides and can very easily be confused with the previously mentioned worms. A few seconds of ID work can save you money. Thresholds and ID information can be accessed easily here under the tab that says insect management. However, a shortcut links to thresholds is here and a link to soybean insect ID is here.

Spray the right insecticide– As mentioned previously, pyrethroids will pick up yellowstriped armyworms and green cloverworms. For corn earworm, pyrethroids will sometimes pick them up, but you may need to use one of the worm-specific materials, as resistance crops up in some spots. Furthermore, they can easily be confused with tobacco budworm, which are resistant to pyrethroids. Finally, beet armyworm, fall armyworm, and soybean looper should be managed using the more worm-specific materials, like Intrepid Edge, Prevathon, or Steward.

Written By

Photo of Dr. Dominic ReisigDr. Dominic ReisigAssociate Professor and Extension Specialist (252) 793-4428 dominic_reisig@ncsu.eduEntomology and Plant Pathology - NC State University
Updated on Jul 6, 2016
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