State Agencies Ask People To Check For The Woolly Adelgid

Boxwood Blight

Avoid oak wilt: Don't prune or injure oak trees during greatest risk period

   The hemlock woolly adelgid (HWA) is a serious threat to Michigan’s eastern hemlock, and forest health experts from the Michigan Department of Natural Resources and Michigan Department of Agriculture and Rural Development are asking residents in west Michigan to check their trees for this harmful insect.
   These tiny insects secrete white wax as they feed on sap. HWA feeding also can kill needles, shoots and branches. Over time, growth slows as trees become less vigorous. Eventually, infected trees may take on a grayish-green appearance. HWA often kills infested trees when combined with other stress factors, such as drought.
   Hemlock woolly adelgid has been found in several locations in Park, Port Sheldon and Spring Lake townships in Ottawa County, as well as in Norton Shores and Whitehall in Muskegon County.
Efforts to find additional HWA locations are ramping up across the state. In cooperation with MDARD, Michigan State University and others, DNR staff this winter will be searching for HWA in state parks, state game areas and eastern hemlock trees all over Michigan.
   "We’re asking for assistance from the public in detecting occurrences of hemlock woolly adelgid in Michigan,” said Roger Mech, DNR forest health specialist. “While people are out enjoying our natural resources, we hope they’ll take a moment to check their trees.”
Quickly detecting and eliminating HWA is critical to slowing the spread of this insect. Eggs and very young adelgids can be carried by birds and can be moved on people’s clothing, hemlock nursery trees, logs or firewood.
Hemlock trees can be protected from HWA with proper insecticide treatments.
   “Citizen involvement in reporting and treating HWA is crucial for the future of hemlock trees in Michigan,” said John Bedford, MDARD Pest Response Program specialist. “Examine your hemlocks, or have them examined by a qualified arborist and, if HWA is found, treat them or have them treated.”
   Eastern hemlock is an essential component of Michigan’s forests. Hemlock also is a critical component of wildlife habitat. Brook trout, for example, are more common in streams running through hemlock forests. More than 12 percent (2.3 million acres) of Michigan’s forests contain eastern hemlock.
A statewide response strategy requires knowing precisely where hemlock woolly adelgid occurs. The insects have entered Michigan several times in the past decade from HWA-infested areas of the U.S. Each time HWA has been detected in Michigan, MDARD, the DNR, MSU and the U.S. Forest Service have joined forces to address this threat.
   If you find a possible HWA infestation, take photos, note the location of the affected trees and contact MDARD at800-292-3939 or MDA-info@mic To prevent spread, do not move the potentially infested material.
For more information about hemlock woolly adelgid, visit the Forest Service’s Forest Health Protection website: p/hwa/. For information about treatments, go to

Have an oak tree on your property? To keep it healthy, don’t prune it from mid-April through the summer. That’s a key time for infection with oak wilt, a serious disease that can weaken white oaks and kill red oak trees within weeks.
Oak wilt, caused by a fungus, has been reported throughout the Midwest, including Michigan, said Ryan Wheeler,  invasive species biologist with the Michigan Department of Natural Resources. 
Red oaks are most susceptible to the disease. These trees have leaves with pointed tips and include black oak, northern red oak and northern pin oak. Trees in the white oak group have rounded leaf edges and include white oak and swamp white oak. They are less susceptible.
Symptoms most often appear from June until September.
"Affected trees will suddenly begin to wilt from the top down, rapidly dropping leaves, which can be green, brown or a combination of both colors," Wheeler said.
Oak wilt is spread above ground mainly by sap-feeding beetles that carry the disease spores from an infected tree, or wood cut from an infected tree, to fresh wounds, including pruning cuts, on healthy trees. The infection also spreads below ground, through root grafts among neighboring trees.
The highest risk of infection occurs April 15-July 15, but it is prudent to avoid pruning or injuring oak trees until they have lost leaves for the winter, typically from November through mid-March, Wheeler said. If you must prune or remove oaks during the risk period, or have a tree that gets damaged, immediately cover wounds with tree-wound paint or latex-based paint.
Don’t move firewood, especially if it comes from oak wilt-killed trees, as it can harbor the fungus If you suspect your firewood is tainted by oak wilt, cover it with a plastic tarp all the way to the ground, leaving no openings. This keeps beetles away so they can’t move spores from the firewood to otherwise healthy trees. Once the firewood has been cut long enough, to the point where all of the bark loosens, the disease can no longer be spread.
If you suspect your oak trees have this disease:

Get help from an oak-wilt qualified specialist. Visit for a listing and more information.
Michigan State University’s Diagnostic Clinic can verify infection. Find instructions at  or call 517-355-4536.

Report infections to or by phone at 517-284-5895; you also can use the MISIN website or mobile app.


Boxwood Blight is a very fast spreading disease caused by the fungus Cylindrocladium which affects members of the Buxaceae family including Boxwoods and Pachysandra. This disease spreads by sticky spores which means they do not spread long distances by wind but are spread most commonly by splashing water, plant debris, and sticking to any surface that might come in contact with. These spores may remain alive for up to 10 years. Infected crops will eventually die from this disease so preventative practices are of the utmost importance.

Symptoms of Boxwood Blight include:

>White puffs on the stems and undersides of the leaves
>Brownish spotting on leaves
>Dark lesions on stems
>Partial or total defoliation of plants
>No visible symptoms on the roots

Unfortunately, these symptoms are the same as common Boxwood diseases, which means Boxwood Blight cannot positively be identified except for laboratory testing. If you suspect your Boxwood may be infected, send a sample directly to a lab.