We have received multiple reports of redbanded stink bugs found nearing threshold levels in the Alabama Black Belt this week. Redbanded stink bugs (RBSB) are the most damaging pest of soybeans in Alabama. They are small, green and have a light red, orange or purple band across their shoulders (back). RBSB also have a small spine in between their legs that points back up towards their face. Populations tend to aggregate on early planted soybeans, then move to late planted beans as early planted beans are harvested. They can cause economic damage until the R7 growth stage, unless there are adverse environmental conditions that promote poor seed quality (i.e., cool, wet).
RBSB are more difficult to control, particularly when the
nymphs appear. If adults and nymphs are found (threshold=4/25 sweeps), then a
full rate of bifenthrin + 0.5 lbs ai of acephate is needed for control. If sub-thresholds
are found, then a full rate of bifenthrin plus a neonicotinoid (imidacloprid)
may provide adequate control. If a threshold population of adults only are
found, we recommend making an application of bifenthrin to knockback adults and
try to stop egg lay.
Our soybean looper traps continue to be high across the state, but we have received few reports of damaging levels of worms in the field. Small loopers are highly sensitive to environmental conditions and are prone to "crash" if a cool snap hits. That is why most thresholds say to only count worms that are >1/4 or 1/2 inch. If threshold populations (19/25 sweeps, prevent 20%-30% defoliation) are found, then diamides (Vantacor, Besiege, Elevest) or Intrepid Edge is needed for control. Loopers are more difficult to control than velvetbean caterpillars or green cloverworms.
As always, if we can ever be of any help, or if you would like to provide input on the situation in your area, please don’t hesitate to reach out (Scott Graham: 662-809-3368; Ron Smith: 334-332-9501). To stay up-to-date on the Alabama insect situation, subscribe to the Alabama Cotton Shorts Newsletter, Alabama Crops Report Newsletter, and the Syngenta Pest Patrol Hotline.
