After scouting soybean fields across southeastern counties for the past several weeks, the brown marmorated stink bug has arrived in southern Lancaster County.
Brown marmorated stink bug levels were discovered to be above threshold levels in both corn and soybean fields. Field margins (20 – 40 feet) had significant levels of pests, while field interiors remained below economic levels.
As we continue into August, we are expecting that BMSB populations will continue to increase in soybeans. In fact, entomologists in Maryland are reporting that stink bug populations have jumped five to 10 fold in the past week at their monitoring stations, indicating that the summer adults have arrived.
Adult bugs have wings, which allow them to move around and invade fields and be detected at monitoring stations.
In Pennsylvania, we expect to start seeing large populations developing on the edges of soybean fields.
Considering that BMSB move into bean fields from the edges, this would be the best location to determine if your field is infested with the pest. Start scouting field edges that border woodlots and corn fields.
We recommend scouting 10 different locations, sweeping 15 times in each location. Again, start on the edge and move toward the middle of the field as you progress.
Use an economic threshold of 2.5 stink bugs per 15 sweeps in narrow-row beans or 3.5 stink bugs in 15 sweeps in wide row beans.
For management options in soybeans, see the Penn State Agronomy Guide’s pest management section http://extension.psu.edu/agronomy-guide/pm/sec4.
From laboratory tests and some field work, it seems products that contain the active ingredient bifenthrin (Brand name Brigade) are a good option for stink bug control. This active ingredient is only one of many with a label for BMSB. However, it also does a good job on two spotted spider mites which are also beginning to invade soybean fields here in the state.
The maximum application rate for Brigade in soybeans is 6.4 ounces per acre. When using Brigade, it is important not to apply the insecticide within 18 days of harvest.
In many cases where BMSB populations are above the threshold level, a perimeter spray should be sufficient. However, it may need to be repeated as stink bugs continue to enter soybean fields throughout the summer months.
We have provided a link to a very informative BMSB webinar narrated by Ames Herbert Jr., who is the professor of entomology at Virginia Tech. This is an excellent summary of BMSB biology, damage, and management.
Most folks that will be encountering BMSB will likely learn a lot from this presentation — http://www.plantmanagementnetwork.org/edcenter/seminars/BMSB/player.html.
In addition to causing damage to soybeans, brown marmorated stinkbugs can also cause damage to corn. According to David Buntin of the University of Georgia, “Corn is most susceptible to stink bug injury during ear formation before tasseling stage. Bugs will feed through the sheath, causing a dead spot on the ear (VT).”
While scouting bean fields in the area several days ago, we noticed BMSB populations in corn fields adjacent to the bean field where we previously discovered BMSB populations.
Brown marmorated stink bug populations in corn have already been discovered; therefore it would be wise to keep an eye on your corn fields as well to catch the pest before too much damage is done.
Along with the BMSB, we have been noticing spider mite populations, Japanese beetle populations and Mexican bean beetle populations as well as grasshopper populations in soybean fields across the southeastern counties.
Populations of these pests have been variable across the counties, which is why it is important not to rely on pest reports from your neighbor. Try to scout your fields as much as you can to catch pest populations before they reach the economic threshold.