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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).
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.
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.
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: