Michigan brown marmorated stink bug update – July 31, 2018
BMSB continue to be caught in traps in southern Michigan; keep a look-out for signs of feeding damage in susceptible crops.
Brown marmorated stink bugs (BMSB) are being monitored at more than 80 orchards or vineyards, and a few vegetable production sites. Over the past few weeks, activity has increased in association with these crops in southern Michigan counties, but we have not heard any new reports of fruit damage.
This time of year, based on growing degree days used in a model to predict BMSB activity, nymphs of all stages are likely to be present and actively moving into fruit and vegetable crops from non-crop hosts in field margins or from fields of soybeans that are beginning to dry down. As nymphs continue to move around in the landscape, crops near favored hosts are expected to be at higher risk of feeding injury. The oldest of these nymphs are expected to start the transformation into summer adults in the next week or two and they should be more responsive to the aggregation pheromone used in monitoring traps.
To know whether this pest is active in an orchard, use limb-jarring over a white sheet or tray and stink bugs will drop out of the tree onto the tray. Do this in trees at the edges of orchards next to woodlots and at the margins of orchards that had evidence of feeding damage last year. There is no threshold for triggering management using the limb-jarring method, but if you are finding nymphs or adults in orchard edges it would be a good idea for your next cover spray to use a material that is also effective against BMSB.
A threshold has been developed for BMBS using traps baited with the Trece dual lure. The recommendation is to count the number of nymphs and adults that accumulate in perimeter traps around a 10-acre or less orchard block, and when 10 BMSB (nymphs or adults) have been captured, that triggers a spray. Start the accumulation count over once a spray has been applied.
In addition to the other materials listed as effective against BMSB in tree fruit (see MSU Extension’s Michigan Fruit Management Guide for 2018, E-154), for the 2018 growing season, Michigan pome and stone fruit growers also have a Special Use label (a.k.a. Section 18) for dinotefuron (sold as Venom or Scorpion) available to them. Contact your local Michigan State University Extension educator to obtain a copy of the label if you would like to use one or the other of these products as it is not yet posted to the MDARD website.