Common Stink Bugs in Corn and Soybean

KEY POINTS

  • Increased stink bug populations can occur after mild winters and in cropping systems that use no-till and/or cover crops.
  • Overwintered stink bugs will feed on corn seedlings in the beginning of the growing season and on ears and grain after pollination and move to soybeans to feed on pods and seeds.
  • Soybean seeds can be destroyed or reduced in quality, oil content, and germination potential.

Scouting and Thresholds

When scouting for stink bugs in corn and soybean, concentrate on field edges first as initial outbreaks usually occur in border rows. If stink bug damage is noted on the field edges, examine the interior of the field. Note the extent of damage and count the number of stink bugs (large nymphs and adults) per plant as economic thresholds are based on these parameters. Thresholds vary by region and stink bug species present. Check with local university extension for economic threshold recommendations in your area.

Corn. To protect stands, scout for stink bugs during the two weeks following emergence, and continue scouting through pollination to protect the developing ear. The pre-tassel stage, when the ear is forming, is the most critical stage as feeding during this time can result in severely deformed ears (Figure 4). Look for stink bugs on the stalk, especially in the area where the ear is beginning to form.

Soybean. Stink bugs generally move to soybean later in the season. Stink bug control is most critical during the R3-R4 (pod establishment and elongation) through R5.5 (seed fill) growth stages. Scout weekly using a sweep net or by inspecting individual plants (recommended for the brown marmorated stink bug).

 

Figure 1. Green stink bug adult (left; photo source Susan Ellis, Bugwood.org) and nymph (right; photo courtesy of Ted MacRae).

 

Figure 2. Brown stink bug adult (top; photo source Russ Ottens, University of Georgia, Bugwood.org) and nymph (bottom; photo courtesy of Ted MacRae).

Management

If stink bug populations reach economic thresholds, an insecticide application may be warranted. Damage to crops may be most severe near tree lines, and field perimeter treatments may temporarily stop a stink bug invasion, though likely for only a short period of time as adult stink bugs can move freely in and out of fields. Check with your local university extension office for products recommended for stink bug control in your region. Many insecticides are effective against stink bugs; however, differences in control are often observed between brown stink bugs and green stink bugs, with some insecticides, such as pyrethroids, being more effective on green stink bugs.

  • Ground applications are generally more effective than aerial applications because they use higher spray volumes that provide better coverage and better canopy penetration.
  • After stink bug emergence, early burndown of a cover crop can help reduce a food source and lower stink bug populations.
  • Insecticidal seed treatments may provide some protection for a short time after emergence.
 

Figure 3. Brown marmorated stink bug. Photo source Susan Ellis, Bugwood.org. Brown marmorated stink bug can be distinguished from brown stink bugs by the white bands on the antenna.

 

Figure 4. Varying degrees of stink bug damage to corn ears and soybean pods and seeds. Soybean photo source: Ric Bessin, University of Kentucky.

Table 1. Damage to corn and soybean.
Common name Feeding site and damage (Figure 4)
Green stink bug (Figure 1) Soybean: pierce pods and destroy or severely damage the developing seed; pods take on flattened appearance; unfilled pods can cause delayed maturity
Brown stink bug (Figure 2) Corn: feed on kill seedlings, damage young leaves and earsSoybean: pierce pods and destroy or severely damage the developing seed; pods take on a flattened appearance; unfilled pods can cause delayed maturity
Brown marmorated stink bug (Figure 3) Corn: feed on developing ears causing deformed ears with aborted and shriveled kernelsSoybean: pierce pods and destroy or severely damage the developing seed' pods take on a flattened appearance; unfilled pods can cause delayed maturity.

Factors that can Increase Stink Bug Populations

Stink bug populations can increase from any practice that increases winter ground cover. The following are field management practices that can potentially increase stink bug populations:

  • No-till. Stink bug populations overwinter in crop residue which can result in severe damage to corn seedlings.
  • Cover crops. Cropping systems that include cover crops are especially at risk for stink bug damage. A cover crop provides an overwintering site and an early season host on which insect populations can build before moving on to emerging corn plants.
  • Improper planting.Stink bug damage can occur to corn seeds and seedlings when seed slots are not closed properly during planting, which can allow stink bugs to access the underground stem and growing point of the corn seedling.
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