Troubleshooting
Green Ash problems — and how to fix them
Green Ash (Fraxinus pennsylvanica) is generally forgiving once you match its basics, but a few issues come up again and again. Here is what each one looks like, why it happens, and the fix.
Emerald Ash Borer (EAB)
Agrilus planipennis larvae tunnel beneath the bark, disrupting water and nutrient transport. Signs include D-shaped exit holes, S-shaped galleries under bark, crown dieback, and epicormic sprouting. No garden-scale cure once heavily infested; preventive systemic insecticide (imidacloprid or emamectin benzoate) can protect high-value specimens.
Ash anthracnose
Fungal infection (Gnomoniella fraxini) causing brown blotches along leaf veins in cool, wet springs. Rarely fatal but disfiguring. Rake and dispose of fallen leaves; fungicide applications in early spring can reduce severity on young trees.
Ash yellows (phytoplasma)
Systemic phytoplasma disease causing witches'-broom, pale foliage, and premature decline. No cure; affected trees should be removed to prevent spread via leafhoppers. More prevalent in stressed or drought-affected specimens.
Prevent green ash problems before they start
Most green ash issues are care-mismatch, not bad luck. Dial in the basics:
Green Ash problems — FAQ
Why is my green ash emerald ash borer (eab)?
Agrilus planipennis larvae tunnel beneath the bark, disrupting water and nutrient transport. Signs include D-shaped exit holes, S-shaped galleries under bark, crown dieback, and epicormic sprouting. No garden-scale cure once heavily infested; preventive systemic insecticide (imidacloprid or emamectin benzoate) can protect high-value specimens.
Why is my green ash ash anthracnose?
Fungal infection (Gnomoniella fraxini) causing brown blotches along leaf veins in cool, wet springs. Rarely fatal but disfiguring. Rake and dispose of fallen leaves; fungicide applications in early spring can reduce severity on young trees.
Why is my green ash ash yellows (phytoplasma)?
Systemic phytoplasma disease causing witches'-broom, pale foliage, and premature decline. No cure; affected trees should be removed to prevent spread via leafhoppers. More prevalent in stressed or drought-affected specimens.