Jerry Brust, IPM Vegetable Specialist, University of Maryland; firstname.lastname@example.org
There has been a large and rapid increase in brown marmorated stink bug (BMSB) in some pepper fields in the past week in central Maryland. Numbers just two weeks ago in these areas were very low with just a few nymphs observed. We know that BMSB populations tend to increase in August and through the fall into the first frost, but this was such a rapid increase that a great deal of damage was done to bell and banana peppers.
These peppers had been treated with chlorantraniliprole (Coragen) and this took care of any worm problems very well, but the growers did not think stink bug. There were 8-10 nymphs and 2-3 adult BMSBs per plant in these fields. Damage to peppers as you might guess was extensive (Fig. 1). Much of the feeding appeared to be done by nymphs (Fig. 2). BMSB nymphs have a white stripe on all six of their legs, which is unique compared with our most common native stink bug species. This white stripe fades when nymphs become adults.
Besides the white ‘cloudy spots’ on fruit, many peppers had dark brown and red as well as bright white areas (Fig. 1). These bright white areas were found to have yeast growing within the wound that from previous studies we learned has been injected by the BMSB when it feeds.
One odd thing from the BMSB outbreak was that tomato fields that were next to or very close to the pepper fields had almost no BMSBs in them. Whether this would have changed soon we are not sure as the growers did not take any chances and treated.
Figure 2. BMSB nymphs feeding on pepper