Pest description and crop damage An invasive pest that has been increasingly attacking hazelnuts in the Willamette Valley. There are five immature stages, and all but the first feed on the plant. Early season feeding and reproduction in the orchard can lead to damaging populations that can damage kernels later in the growing season. Nymphs initially feed on vegetative structures such as leaves and husks, but later stages feed directly on nuts. Shell thickness or hardness does not protect kernels from feeding damage as the mouthparts of the insect can penetrate the shell allowing it to feed on the kernel within. Depending on when the insect feeds on the nuts, they can cause blanks, shrivel or corking damage on the kernels. See OSU EM 9102: How to Recognize Brown Marmorated Stink Bug Damage in Commercial Hazelnuts. Much of the damage to hazelnut kernels occurs in the latter part of the season according to research.
Biology and life history
Pest monitoring Pheromone traps, visual samples, or beating trays are good methods for detection. Place traps on orchard borders, rather than in orchard interiors, and monitor orchard border vegetation. Management thresholds based on trap captures or other sampling methods are not yet firmly established, but any trap captures warrant scouting of the orchard to detect potentially damaging populations. Presence of nymphs in the crop can be an indicator for potential damage. Stink bugs are very cryptic and can be difficult to detect in the crop. Slow movement when scouting can be important to detect nymphs without triggering a hiding or flight response. Scan the underside of leaf surfaces for egg masses and early nymphs. Standardize the amount of time spent visually searching for stink bugs (e.g., ten minutes) to compare samples from different times of the season or locations. Note that the highest pressure from this pest will be late in the season (Aug thru Oct), although damaging levels can sometimes build much sooner. The population level at the end of the previous season, winter survival, and weather during spring are all factors affecting current season population levels. As fall approaches, BMSB will move to buildings to overwinter in aggregations. Overwintering populations in barns or outbuildings may move right into the orchard in spring if it is nearby.
The samurai wasp, Trissolcus japonicus, an adventive parasitoid wasp from Asia was detected in Vancouver, Washington in 2015 and in Portland, Oregon in 2016. This parasitoid is becoming established in the Willamette Valley and researchers are actively redistributing the wasp. This wasp attacks the stink bug egg masses, turning them from bright green or blue to black as the wasps develop in the egg mass and eventually chew their way out of the eggs. The wasp is known to be a highly effective parasitoid against brown marmorated stink bug in Asia. Native parasitoids and predators can also help limit stink bug populations. There are numerous predators (spiders, katydids, lacewing larvae) that attack the eggs and early nymphs. The mature nymphs and adults have fewer natural enemies, but sometimes birds and spiders will target them. Crabronid wasps (Astata bicolor) are a specialized predator that sting the nymphs to paralyze them, then carry the paralyzed stink bugs to their nests in the ground where the stink bugs are used to provision the nest for their young. Note that most chemical treatments for BMSB are broad-spectrum, so treatments may negatively impact biological control and cause flare-ups of secondary pests such as scale and aphids.
Hand-collecting and killing of egg masses, nymphs, and adults can be an effective management strategy if there are very few trees, but this method is not practical on a commercial scale. Home orchardists may also find that exclusion netting is possible. Eliminating or excluding aggregations of adults in overwintering sites, including farmhouses and outbuildings, may be beneficial to reduce local populations for commercial growers and home orchardists.
Management-chemical control: HOME USE
- azadirachtin (neem oil)-Some formulations are OMRI-listed for organic use.
- lambda-cyhalothrin (Bonide Fruit Tree & Plant Guard)
- pyrethrins-Some formulations are OMRI-listed for organic use.
Management-chemical control: COMMERCIAL USE
- acetamiprid (Assail 70WP) at 0.57 to 1 oz/100 gal water (2.3 to 4.1 oz/A). PHI 14 days. No more than 4 applications per season.
- beta-cyfluthrin (Baythroid XL) at 2 to 2.4 oz/A. PHI 14 days. REI 12 hr.
- Brigade WSB at 0.05 to 0.2 lb ai/A. PHI 7 days. REI 12 hr. Do not graze livestock on treated cover crops. Highly toxic to bees and toxic to fish and aquatic invertebrates.
- Fanfare EC at 3.2 to 12.8 fl oz/A. PHI 7 days. Do not graze livestock on treated cover crops. Highly toxic to bees and toxic to fish and aquatic invertebrates.
- clothianidin (Belay) at 6 oz/A. PHI 21 days. REI 12 hr. Systemic activity. Avoid drift to flowering crops. Low rate for low infestation and/or smaller trees. No more than 0.2 lb ai per year.
- fenpropathrin (Danitol 2.4 EC) at 10.3 to 21.3 oz/A. PHI 3 days. REI 24 hr. At least 50 gal water for ground applications. Note buffer requirements for use near aquatic zones.
- imidacloprid (Admire Pro and generics) at 3.4 to 7 fl oz/A. PHI 7 days. REI 12 hr.
- kaolin-Some formulations are OMRI-listed for organic use. Kaolin can act as a deterrent to BMSB.
- Drexel L-C at 2.56 to 5.12 fl oz/A. PHI 14 days. REI 24 hr. Do not exceed 0.16 lb ai/A per season or 0.12 lb ai post bloom.
- Grizzly Too at 1.28 to 2.56 fl oz/A. PHI 14 days. REI 24 hr. Do not exceed 0.16 lb ai/A per season or 0.12 lb ai post bloom.
- LambdaStar at 2.56 to 5.12 fl oz/A. PHI 14 days. REI 24 hr. Do not exceed 0.16 lb ai/A per season or 0.12 lb ai post bloom.
- Warrior II at 1.28 to 2.56 fl oz/A. PHI 14 days. REI 24 hr. Do not exceed 0.16 lb ai/A per season or 0.12 lb ai post bloom.
- Ambush 25W 12.8 to 25.6 oz/A. PHI 14 days. REI 12 hr. Do not graze treated orchards. Extremely toxic to fish and aquatic habitat.
- PermaStar AG at 8 to 16 oz/A. PHI 14 days. REI 12 hr. Highly toxic to bees, toxic to fish and aquatic invertebrates.
- Pounce 3.2 EC at 0.5 to 1 pint/A. PHI 14 days. REI 12 hr. Do not graze treated orchards. Extremely toxic to fish and aquatic habitat.
- sulfoxaflor (Transform WG) at 2 to 2.25 oz/A. PHI 7 days. REI 24 hr. Suppression only. No more than 8.5 oz per year. Avoid drift to blooming crops and weeds to protect pollinators.
- zeta-cypermethrin (Mustang Maxx) at 3.2 to 4 oz/A. PHI 7 days. REI 12 hr.