Current Soybean Insect Thesholds- Note that Stink Bug Sweep Net Threshold Changed in 2013

I’ve been getting a lot of questions on soybean insect thresholds.  These were covered in a blog article three weeks ago, but I hope this article is a bit more specific.  Note that our stink bug threshold was raised from 2-3 stink bugs/15 sweeps (one sweep = one “swoosh” of the net) to 5 stink bugs/15 sweeps in 2013.  This was covered in a recorded presentation, many county meetings and previous blog articles.  Here are the thresholds:

Image from Iowa State University Extension.

Image from Iowa State University Extension.

Defoliators: 15% during the reproductive stages and 30% pre-bloom.  These include armyworms, bean leaf beetle, green cloverworm, loopers, etc.  Be sure to estimate defoliation throughout the entire canopy, not just on the top visible leaves.  Loopers tend to defoliate from the bottom up.

Corn earworm/tobacco budworm: The threshold varies with insecticide choice, price of beans, sampling method and row spacing.  I suggest using the earworm/budworm online threshold calculator as a guide for treatment.  This calculator has been updated.  For example, the threshold does not change when the price of beans exceeds $10/bu.

Stink bugs: Stink bug online threshold calculator.

Kudzu bug: 5 per plant for seedling beans and 1 nymph per sweep (one sweep = one “swoosh” of the net) during and after July.

Written By

Dr. Dominic ReisigAssociate Professor and Extension Specialist (252) 793-4428 Entomology and Plant Pathology - NC State University

Posted on Aug 20, 2014

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