Soybean South


Redbanded Stink Bug
Is On The Move

Redbanded stink bug control requires three to four timely insecticide
applications to minimize yield loss and maintain seed quality.

By Carroll Smith

Not just a bug of a different color, the redbanded stink bug is a real stinker for soybean producers as it has become the dominant pest among the complex of three stink bug species in the Mid-South – the southern green, the brown and the redbanded.

This pest is generally distributed across the Texas Gulf Coast, all of Louisiana and south-central Mississippi. Now, it’s also beginning to infest soybean fields in southern Arkansas and northern Mississippi.

“The redbanded stink bug is a major concern because it is increasing the cost of soybean insect pest control. That cost of control is dictated by an increase not only in the frequency of applications compared to previous years but also the fact that we are having to use products at higher rates or co-applications of two products,” says Roger Leonard, LSU Ag-Center research entomologist.

“In spite of more intense insecticide use, we are still suffering stink bug damage to soybean seed,” he adds.

To help prepare soybean farmers for the increase in control costs, LSU AgCenter Ag economists have included three to four insecticide applications for stink bugs in their soybean production budget instead of just one that was required a few years ago. Fortunately, the products applied to control the redbanded stink bugs will also control the southern green and brown species.

Lower action threshold triggers sprays
Leonard emphasizes that it is critical to scout for this pest and make timely applications not only to minimize yield loss but also to maintain soybean seed quality, which is a big issue today for producers, elevators and buyers.

To make sure that applications go out timely to prevent the buildup of very high infestations, the action threshold for redbanded stink bugs is lower than for the other species. For everything except the redbanded, the threshold generally is nine bugs per 25 sweeps or 36 in 100 sweeps. For the redbanded stink bug, the threshold is six bugs per 25 sweeps or 24 per 100 sweeps.

“During the early to mid-reproductive growth stages – usually R4 into R6 or early R7 – economic infestations are causing significant yield losses,” he says. “If an application is missed, redbanded stink bugs can create significant levels of seed injury (even beyond the R7 growth stage) that result in diseased or rotten seed within the pods. These seed have little to no value and cause growers to be heavily docked for seed injury or, in the worst cases, have the entire transport load of seed rejected. The elevator simply won’t accept them.”

Other related issues
Leonard notes two other important issues that have come into play with the redbanded stink bug.

First, later-planted soybeans, which are representing a much smaller acreage across the Mid-South, are in greater danger of injury, whereas the Group IVs included in early production systems escape much of the intense pressure from heavy infestations that migrate to later-planted fields.

“It becomes an island effect,” Leonard says. “If you have the same pest population distributed across 500,000 acres early in the year, it’s not nearly as devastating as having that same population later in the year distributed across 50,000 acres.”

The LSU AgCenter entomologist also notes that the sprays going out for stink bugs are triggering problems with other pests, such as soybean loopers. Therefore, not only do stink bugs have to be controlled in the later-planted soybeans, but treatments may also have to go out to control loopers.

“Unfortunately, the treatments used for stink bugs have no activity on loopers, and the treatments used on loopers have little to no activity on stink bugs, which further drives up the cost of pest management and production,” Leonard says.

Needless to say, these pesky bandits are enough to make Mid-South soybean producers see red.

Control Measures For Primary Nematode Pests In South Carolina

Nematode losses in South Carolina soybeans are caused primarily by Southern root-knot, soybean cyst, Columbia lance and reniform nematodes.

Root-knot nematodes: The most cost-effective way to control root-knot nematodes is to plant resistant varieties. If a nematicide is used, it should be applied to a root-knot nematode resistant cultivar. In-row sub-soiling or any other cultural practice that helps reduce stresses can help limit damage due to root-knot nematodes.

Soybean cyst nematode: Soybean cyst nematode is easily spread in soil clinging to equipment, runoff water, blowing dust or soil peds that may contaminate seed. Make sure seed for planting are free of all foreign matter. Clean all equipment before moving from an infested field, or even a suspected field, to another field. Avoid monocropping soybeans, especially the same cultivar. Rotation with a non-host crop, such as corn, cotton, peanut or sorghum will greatly reduce inoculum for the next year’s crop. Where soybean cyst nematodes are severe, two years of a non-host crop may be needed.

Columbia lance nematode: Try to use a cultivar tolerant of Columbia lance nematode. In-row sub-soiling will reduce, but not eliminate, losses from Columbia lance nematode in most Coastal Plain soils. Planting early, prior to mid-May, can reduce losses. Avoid double-cropping soybeans in Columbia lance nematode fields. Use a low rate of a nematicide at planting on a tolerant cultivar.

Reniform nematodes: Soybean varieties with resistance to cyst races 1 and 3 may also be resistant to reniform nematode. A one-year rotation with a non-host crop, such as corn, will usually reduce the population density to a level where a reniform nematode susceptible soybean variety can be grown. If reniform populations are very high, it may take a two-year rotation to lower them sufficiently. Use of a nematicide may help to reduce yield losses due to reniform nematode.

Source: John D. Mueller, 2009 South Carolina Soybean Production Guide