Mid-Michigan has lost more shade canopy in the last twenty years than at any time since the original Dutch Elm Disease wave in the 1950s. The current culprit is Emerald Ash Borer, but Oak Wilt is creeping into Ingham, Eaton, and Clinton counties year after year, and Dutch Elm Disease is still active in the older surviving elm population. Add in the usual cast of secondary pathogens (Verticillium wilt, anthracnose, oak decline, ash yellows) and there's a lot going on.
If you've got a tree that's looking off (early color change, thinning canopy, dieback at the top, bark falling off, suckers at the base), don't guess. Get a real diagnosis. Wrong treatment is worse than no treatment, and a tree that gets misdiagnosed often becomes a hazard before the homeowner figures out what's actually going on.
Emerald Ash Borer (EAB)
EAB has been the dominant story in Michigan tree care since the bug arrived in Detroit in 2002. Lansing got hit badly in the late 2000s, and even now, two decades in, we're still removing ash trees that died years ago and were never taken down. We're also still treating ash trees that are healthy enough to save.
What EAB Looks Like
- Top-down canopy thinning. The upper third of the tree dies first.
- Epicormic sprouting. Random shoots growing out of the trunk and major limbs, often near the ground.
- Bark splits and "blonding" where woodpeckers have stripped the bark hunting for larvae.
- D-shaped exit holes about 1/8 inch wide in the bark of larger limbs and trunk.
- Galleries (S-shaped tunnels) under the bark when you peel it back.
Treatment with Trunk Injections
The standard of care for EAB is emamectin benzoate trunk injection (brand name TREE-age). It's an insecticide injected directly into the lower trunk, where it gets distributed through the vascular system to the entire canopy. One treatment lasts 2 to 3 years. Treatment cost runs roughly $9 to $12 per inch of DBH (diameter at breast height), so a 20-inch ash might run $180 to $240 per treatment cycle.
We treat ash trees from May through August. Trees with less than 30% canopy decline have an excellent prognosis. Trees with 30 to 50% decline can sometimes be saved but it's a coin flip. Past 50% decline, treatment is throwing money away and the tree should be removed before the wood gets brittle and dangerous to climb.
Why You Can't Just Wait It Out
We've heard "I'll just wait until the EAB wave passes" since 2008. It hasn't passed. EAB is now established in over 30 states and won't disappear from Michigan in our lifetimes. Healthy ash trees need ongoing treatment to survive, and untreated trees in the Lansing area will eventually die. There's no magic recovery on the horizon.
Oak Wilt
Oak Wilt is a vascular fungus (Bretziella fagacearum) that's lethal to red oaks within weeks of infection and slow to fatal in white oaks. It's been confirmed in dozens of Michigan counties including Ingham. The MDARD (Michigan Department of Agriculture and Rural Development) tracks new infection sites, and the disease is spreading.
How It Spreads
Two ways. Above ground, sap-feeding beetles pick up fungal spores from infected trees and carry them to fresh wounds on healthy trees during the warm months. Below ground, oaks growing within about 50 feet of each other can share grafted root systems, and the fungus moves underground from tree to tree.
The Summer Pruning Ban
The single most important rule for oak owners in Lansing: do not prune oaks between April 15 and July 15. This is when the sap beetles are most active and a fresh pruning cut is essentially a "feed me here" sign for the disease vector. Ice storm damage that exposes fresh wood during this window can also lead to infection. We paint emergency cuts with wound dressing during this period, even though it's normally not recommended for tree health.
Diagnosis and Management
Symptoms include rapid leaf wilting (red oaks can defoliate in 2 to 6 weeks), browning from the leaf tip inward, and sometimes a fungal mat under the bark that smells fruity. Diagnosis is confirmed with a lab sample sent to MSU Diagnostic Services. Once confirmed, management depends on the situation:
- For an isolated infected red oak, we typically recommend removal and burning or chipping (to destroy the fungal mat) plus root graft barrier trenching to protect adjacent healthy oaks.
- For nearby healthy oaks at risk, propiconazole trunk injection can offer prophylactic protection lasting up to 2 years.
- Wood chips from infected oaks should not be moved off site.
Dutch Elm Disease (DED)
Most folks assume DED is "from the 1950s" but the disease is still active. We see it in Lansing every year, mostly in surviving mature American elms and in vulnerable elm cultivars. The fungus (Ophiostoma novo-ulmi) is spread by elm bark beetles and through root grafts, similar to Oak Wilt.
Symptoms
- "Flagging" of one or more branches with sudden wilting and yellowing.
- Leaves that wilt but remain attached, eventually turning brown.
- Brown streaking in the sapwood when you peel the bark on a wilting branch.
Treatment Options
For valuable individual elms, propiconazole trunk injections can prevent infection or sometimes treat early-stage cases. The treatment must be done before infection or in the very early stages, and it's not cheap, often more than EAB treatment because of the difficulty of getting full vascular distribution in a mature elm.
For trees already showing significant DED, prompt removal is the standard recommendation. The infected wood needs to be removed from the site, and any nearby elms should be evaluated for prophylactic treatment.
Other Issues We Diagnose
Verticillium wilt on maples. Soil-borne fungus. No effective treatment. Often misdiagnosed as drought stress.
Anthracnose on sycamore, oak, and ash. Cosmetic damage in most cases, only serious in successive wet springs.
Apple scab and cedar-apple rust on ornamental crabapples and pears. Manageable with cultural practices and fungicide if cosmetic damage matters to you.
Bronze birch borer on white birch. We see plenty of these dying because the tree was planted in a hot exposed yard outside its preferred niche.
Spongy moth (formerly gypsy moth) defoliation on oaks. Periodic outbreak years. Healthy oaks can usually weather one to two seasons of defoliation but combined with Oak Wilt risk it gets serious.
Our Diagnostic Process
An ISA-certified arborist comes to your property and walks the tree, checks the canopy with binoculars, examines bark and base, and looks at adjacent trees. For ambiguous cases we'll take samples and send them to MSU Diagnostic Services or a similar lab. We give you a written report with our findings, treatment options (and costs), and our honest opinion on whether treatment is worth pursuing or whether the tree should be removed.
FAQ: Tree Disease in Lansing
Maybe. We need to look at canopy condition. Less than 30% decline, treatment has a high success rate. 30 to 50% decline, it's a judgment call. More than 50% decline, removal is the right move.
Rapid summer wilt, especially in a red oak, is the classic sign. We confirm with a lab sample. Don't take cuttings yourself, that can spread the disease.
Yes, when done properly. We use micro-injections that minimize trunk damage. Repeated injections over many years can leave small wounds, but the alternative for EAB and DED is much worse.
Soil-drench imidacloprid products work for small ash trees (under about 14 inches DBH). For larger trees they don't deliver enough active ingredient and treatment fails. Trunk injection is the proven option for mature ash.
The Lansing Forestry Division manages right-of-way trees with a limited budget. Some are treated, many are removed. If you want certainty for a parkway ash, you can sometimes pay for treatment yourself with city permission. We can help with that conversation.