Forest Insect and Disease Newsletter
Exotic Insects and Diseases
The bad news is that on July 21st , an emerald ash borer (EAB) was discovered in Shoreview in an area adjacent to the Ramsey County Rice Creek Regional Trail. The good news is that a savvy homeowner was alert to the symptoms of EAB and notified the city about her concern. When the city inspected the tree, an adult beetle was discovered and the city promptly notified the Minnesota Department of Agriculture (MDA) and staff from the MDA went to the location to verify the finding. After confirming the identity of the beetle, USDA Animal and Plant Health Inspection Service staff placed a single trap and caught 21 adults EAB – by far, the most beetles caught on a single trap in Minnesota.
The ash tree in question showed the typical symptoms of crown die-back and sprouting along the trunk, but staff saw no exit holes. Other than that, there was no "smoking gun" no backyard woodpile containing ash logs, not even any other symptomatic trees nearby. What makes the Shoreview find unique is that it is 10 miles from a known infestation. How it got there remains a mystery.
Because the find is so small (one tree) and is adjacent to a native area, the area is a prime candidate for biological control. So the Minnesota Department of Agriculture plans to release non-stinging wasps to help control the EAB population. In the meantime, MDA and Shoreview staff will be working with area residents to identify and remove infested tree(s).
Shoreview is in Ramsey County and is the fourth city in Minnesota to have an infestation, along with St. Paul, Minneapolis, and Falcon Heights. There is also a population of EAB in southeastern Houston County.
Excerpted from a report by Lucy Hunt, MDA, Gypsy Moth Unit Supervisor
The Minnesota Department of Agriculture's (MDA) gypsy moth treatment projects this year included both eradication and Slow-the-Spread (STS) projects. Planning work on the treatments began in the fall of 2010 when individual blocks were defined and areas were finalized in February of 2011. An in-house Incident Command System was used to manage the spray projects, drawing on departmental expertise in planning, public information, operations, and more. Personnel from state, federal, and local organizations were involved throughout the planning process which led to a successful spray program with minimal turbulence.
Eradication- Three eradication sites totaling 1,519 acres in Anoka, Hennepin, and Washington Counties were treated with the organic formulation of Btk (Foray 48B).
Slow-the-Spread- A 342-acre STS site in central Duluth was treated with Btk. Along the North Shore and in Duluth, 114,793 acres were treated with mating disruption product, Disrupt II pheromone flakes. A 460-acre block on Duluth's Park Point was treated with ground-applied SPLAT(R). Products were chosen for each site based on management goals and efficacy. Aerial treatments wrapped up on the evening of July 20 after all acreage was finished.
The Park Point neighborhood of Duluth, situated on one of the world's longest freshwater spits, is too narrow to fly with spray aircraft so a ground application of the mating disruption product SPLAT(R) was planned for the 460-acre site. Sixteen MDA employees and one federal worker applied the product with caulking guns along the length of the spit, including the southern third which is forested and boasts a healthy poison ivy crop.
It seems like only yesterday that the Japanese beetle was a pretty curiosity in the Twin Cities Metro Area. The Minnesota Department of Agriculture was trapping adult beetles, inspecting nursery stock root balls and containers for grubs and ordering treatment when necessary; that all changed in 2002. That year the MDA recognized that the Japanese beetle population, despite concerted eradication efforts, had grown too large in the Metro area for any hope of keeping this non-native, invasive pest at bay—it was declared a 'general pest' to be added to the lengthy list of insects that will eat our ornamental plants.
The Japanese beetle, Popillia japonica is recognized as one of the most damaging pests in the eastern United States and is rapidly climbing up the list of 'bad bugs' here in Minnesota. In addition to the damage inflicted by the adults due to rapid defoliation of susceptible plants, the sheer number of adults hanging on foliage also poses an incredible nuisance to people. Adult beetles clump in large numbers on foliage to feed and mate. The larva which is a white grub eats the roots of turf grasses and when present in large numbers can cause areas of sod to die. The presence of adult beetles on plants and in flight around trees, shrubs and areas of sod during daylight hours makes them particularly visible in the landscape. Beetles emerge from pupae in turf during June and July, however since individual beetles can live for 30 to 45 days and emergence of adults occurs over several weeks, adults may be present into late summer.
Severe defoliation of ornamentals and trees has been reported across the Metro area this year. In past years there have been a few 'hot spots' often near golf courses or other large expanses of turf, but this year damage is widespread as grubs infest more and more lawns and grassy areas as the adult population increases. In many neighborhoods, birch and linden trees sustained 50 to 90 percent defoliation and along many roadways the leaves of Virginia creeper and wild grape growing on fences are completely skeletonized. A large adult population and ample moisture in turf this year are ideal conditions for a bumper crop of larvae – next year may be a very good year for Japanese beetle!
Quarantine prevents import of walnut trees and walnut wood from states with thousand cankers disease
A temporary exterior quarantine announced in February was made permanent this week by Minnesota Department of Agriculture (MDA) Commissioner Dave Frederickson. The quarantine was issued as a preventative measure to help stop thousand cankers disease (TCD) from coming to Minnesota. Products covered by the quarantine include live walnut trees, walnut logs, walnut lumber, walnut nursery stock, wood chips and mulch made from walnut wood, walnut branches and roots, packaging materials made from walnut wood, and all hardwood firewood.
The quarantine does not apply to walnut nuts, nutmeat, walnut hulls, finished products made from walnut wood without bark, or processed lumber that is 100 percent bark-free, and kiln-dried with square edges. Several other states within the native range of eastern black walnut have similar exterior quarantines in place. Announcement of the quarantine comes within a month of the detection of TCD in the state of Virginia, the second state within the native range of eastern black walnut to report the disease.
If suspect trees are spotted, please contact MDA's Arrest the Pest Hotline (1-888-545-6684). More information about TCD and the quarantine can be found on MDA's website.