Pest and disease coverage for Upstate New York trees and shrubs: emerald ash borer, beech leaf disease, spotted lanternfly, oak wilt, and the fungal problems moving through the Rochester region, with what to do about them.
Other sections: Tree Health · Homeowner Guides
Editor's picks
Tan mushroom clusters at your tree's base after a rainy Rochester fall? Armillaria root rot is often already advanced. How to confirm it and what to do.
September 10, 2026
Oak leaves browning at the margins with a yellow halo, worse every August? That reads as bacterial leaf scorch, not oak wilt. How to tell, and what works.
September 10, 2026
Purple-bordered leaf spots on a Rochester dogwood in late spring, then twig dieback? Here is how to confirm dogwood anthracnose and what it needs.
September 10, 2026
Hemlock needles yellow-spotted and thinning, but no white woolly tufts? That points to elongate hemlock scale, not adelgid. How to tell them apart.
September 10, 2026
New shoot tips browning on a Rochester juniper or arborvitae hedge? Phomopsis and Kabatina blight look alike but strike at different times of year.
September 10, 2026
Tiny oyster-shaped bumps crusting the bark of a Rochester lilac, ash or maple? That is oystershell scale, and the treatment window is narrow.
September 10, 2026
Norway maples across Rochester browned and dropped leaves weeks early in 2026. NYS DEC points to a wet spring and tar spot. What it means for your tree.
September 10, 2026
What does emerald ash borer treatment cost per tree in Rochester? Pricing runs by trunk diameter on a repeating cycle, and when it beats removal.
July 22, 2026
Boxwood dropping leaves with black stem streaks may be blight, a fungal disease with no cure. Learn the signs, spread, and how to protect healthy plants.
July 9, 2026
Bronze birch borer kills Rochester birches from the top down, striking drought-stressed white birches. Learn the signs and whether yours can be saved.
July 9, 2026
Dutch elm disease spreads across New York by beetles and root grafts. Learn the first signs, whether a Rochester elm can be saved, and resistant cultivars.
July 9, 2026
Red pimples and fuzzy bumps on Rochester maple and oak leaves are almost always harmless galls from mites or tiny wasps. Here is when one actually matters.
July 9, 2026
A white powdery coating on tree and shrub leaves is powdery mildew. Learn why it is usually cosmetic in Rochester, NY, and how airflow beats spraying.
July 9, 2026
Dark, sour-smelling ooze on your tree trunk is slime flux, a sign of bacterial wetwood. Learn why not to drill it and when a Rochester arborist should look.
July 9, 2026
Bronzed, dusty-looking spruce, arborvitae, or juniper needles in Rochester often mean spruce spider mites. Learn the paper tap test and how to time control.
July 9, 2026
Two-lined chestnut borer kills Rochester oaks already weakened by drought or root stress, working top-down. Learn the signs, recovery odds, and when to act.
July 9, 2026
Cool wet Finger Lakes springs trigger anthracnose on Rochester sycamore, oak, and ash. Learn the scorched-leaf signs and how to tell it from frost.
June 25, 2026
Sticky sap on your car and black film on Rochester tree leaves? Learn the aphid-honeydew-sooty-mold chain and why systemic soil treatment beats washing.
June 25, 2026
Crabapple leaves dropping by July in Monroe County usually means apple scab. Learn the spray-timing playbook and when to replant a resistant variety.
June 25, 2026
Treat or remove your EAB-infested ash in Rochester? Compare treatment cost and timeline against removal, and learn which ash trees are worth saving.
June 25, 2026
Bagworm cocoons disguise as cones until evergreens brown out. Learn ID on Rochester arborvitae and spruce and the narrow June treatment window.
June 25, 2026
Coal-black warty galls on Rochester cherry and plum branches mean black knot. Learn the cut-below-and-dormant-prune protocol and reinfection sources.
June 25, 2026
Blue spruce dropping inner needles in Monroe County? Rhizosphaera needlecast is the likely cause. Learn the purple-banding signs and fungicide timing.
June 25, 2026
Blistered, yellow boxwood leaves in Pittsford and Brighton? Learn to tell boxwood leafminer from blight and the spring treatment window for Rochester.
June 25, 2026
Orange spots on crabapples and gooey galls on junipers? Cedar-apple rust needs both hosts. Learn the two-tree life cycle and what control works.
June 25, 2026
Sunken, oozing bark wounds and branch dieback on Rochester spruce, maple, and honeylocust signal canker. Learn the stress link and the PHC fix.
June 25, 2026
Austrian and Scotch pine tips browning from the top in Rochester suburbs? Diplodia tip blight is likely. Learn how to tell it from drought and burn.
June 25, 2026
Webs in your Rochester tree? Compare eastern tent caterpillar and fall webworm side by side and learn which one actually warrants an arborist call.
June 25, 2026
Burned, hooked branch tips on Rochester pears and crabapples signal fire blight. Learn the shepherd's-crook sign and why wrong pruning spreads it.
June 25, 2026
White cottony tufts on hemlock needles signal woolly adelgid. See how Finger Lakes homeowners can save eastern hemlocks with timed PHC treatment.
June 25, 2026
Skeletonized, lace-like leaves on Rochester lindens and roses mean Japanese beetles. See why bag traps backfire and when systemic PHC is worth it.
June 25, 2026
Black spots on Rochester maple leaves every September? Learn when tar spot is harmless cosmetic damage and when it signals anthracnose or decline.
June 25, 2026
Worried about oak wilt near Rochester? Learn the confirmed New York status, the rapid top-down symptoms, and why summer oak pruning is the real risk.
June 25, 2026
White bumps and sticky black mold on Rochester magnolia, maple, or oak mean soft scale. Learn the symptom chain and the crawler-timing window that fixes it.
June 25, 2026
Spongy moth defoliates Upstate NY oaks in outbreak years. Learn the egg masses to scrape in winter and when a stressed tree needs intervention.
June 25, 2026
Spotted lanternfly is spreading across New York. Learn to ID egg masses, the tree-of-heaven link, and how to report sightings to NYS Ag and Markets.
June 25, 2026
One-sided, branch-by-branch maple dieback in Upstate NY often means Verticillium wilt. Learn the cut-and-streak test and why replanting maples fails.
June 25, 2026
Skeletonized viburnum leaves are spreading across Monroe County. Learn the winter twig-pruning trick, resistant varieties, and when to treat.
June 25, 2026
DIY or call a pro for a Rochester tree pest? Compare horticultural oil, insecticidal soap, soil drench, and trunk injection, and when an arborist wins.
June 25, 2026
Beech leaf disease is spreading across New York. Learn how to spot the dark leaf banding on Rochester beech trees and what to do next.
June 14, 2026
Emerald ash borer is killing ash across Monroe County. Learn the early signs, whether your tree can be treated, and when removal is the safe choice.
June 13, 2026
From the editors
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