Keep On Scouting!

Pests that repopulate and overwinter are particularly challenging in soybean fields

Published on: Aug 7, 2013

Drought conditions controlled some pests last year, but moderate temperatures and delayed planting – combined with pests' ability to overwinter – reveal a different story this season.

That's why some agronomists are recommending increased scouting in soybean fields, especially for soybean aphids and other pests, like the brown marmorated stink bug and kudzu bugs.

"Identified as strong fliers with the ability to hitchhike, both brown marmorated stink bugs and kudzu bugs continue to migrate and increase populations," says Paula Davis, DuPont Pioneer senior manager for insect and disease resistance traits. "Along with soybean aphids, these pests will challenge growers to closely monitor their fields and keep tabs on current threat levels."

Soybean Aphids (Photo by Marlin E. Rice)
Soybean Aphids (Photo by Marlin E. Rice)

BMSB have already been detected in a number of states, up to 40 in total, including every state east of the Mississippi, Dupont Pioneer says. Kudzu bugs have rapidly spread across 10 southeastern states since the first detection four years ago.

The company notes that soybean yields are reduced as a result of feeding damage from BMSB and kudzu bugs. Kudzu bug infestations in Georgia and South Carolina show an average soybean yield loss of 18%, with ranges up to 47%. Growers in Maryland have estimated yield losses greater than 50% at field edges as well as delayed maturity due to early feeding by BMSB.

Know what to look for

To identify the pests, note that the distinguishing soybean aphid characteristic is cornicles, or black "tail pipes" projecting from the rear of the abdomen. The pests are typically light green and less than one millimeter in length with an oval or pear shape.

Brown Marmorated Stink Bug (Photo by Marlin E. Rice)
Brown Marmorated Stink Bug (Photo by Marlin E. Rice)

 Symptoms of infestations include shortened plant height, curled leaves with yellow edges, excessive honeydew on leaves and the presence of ants. Excessive honeydew may also promote mold growth, reducing photosynthesis.

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To distinguish BMSB from the brown stink bug (the term 'marmorated' means having a marbled or streaked appearance), look for a distinct double white band on the antennae, alternating light and dark bands around the abdomen and red eyes.

Soybeans are vulnerable to seed damage by BMSB after the R3 stage leading to deformed seeds and pod loss. In addition, soybean plants retain green stems and mature improperly. The pest may also increase the potential for ear molds and negatively impact seed quality in corn due to ear feeding injury.

Kudzu Bug (Photo by Marlin E. Rice)
Kudzu Bug (Photo by Marlin E. Rice)

Smaller than a stink bug, but larger than an aphid, adult kudzu bugs are shiny, 3.5–6 millimeters in length and brown to olive green in color with light freckled spots. The pests have red eyes and a broadly round tail end.

Kudzu bugs induce stress by feeding on soybean stems and leaves, reducing pods per plant, seeds per pod and seed size. The pest may also reduce yields and cause harvest problems by delaying soybean maturity and causing green stem syndrome. Insecticide treatment must penetrate the canopy to control kudzu bugs effectively.

Source: DuPont Pioneer