The right response to emerald ash borer depends on the tree's condition: a healthy ash is protected before the beetle arrives, an infested ash is treated quickly, and a badly declining ash is checked by an arborist first. Where treatment makes sense, it is a systemic insecticide, one the tree carries through its own tissues, because fertilizer alone does not stop the beetle.

What are the signs of emerald ash borer on an ash?

Small D shaped exit holes in the bark, a thinning canopy, and sections of the crown wilting and dying. An ash with none of these signs can still be protected before the beetle reaches it.

How is a healthy ash treated differently from an infested one?

A healthy ash needs protection in place before the beetle arrives, while an infested ash needs insecticide that reaches the borers fast. Watering Once A Year Insecticidal Drench w/Merit onto the roots in fall or early spring protects a healthy ash through the growing season, while the Multi Insect Killer Tree Injection Kit, injected into holes drilled at the base of the trunk, spreads through an infested tree in about 72 hours.

When is an ash too far gone to treat?

When an arborist judges it is no longer a good candidate for treatment. Once borers are present, control becomes extremely difficult, and damage can keep increasing even after insecticide is applied.

Do the other ash trees on the property need protection too?

Yes, for any ash the owner wants to keep. The beetle lays eggs on healthy trees as well as stressed ones, and untreated ash in an infested area are expected to die within about 10 years.

Frequently Asked Questions

How much drench does an ash need?

One ounce per inch of trunk circumference. The trunk is measured around at chest height, so a 32 oz bottle treats a tree 32 inches around.

Does the drench work quickly on a tree already infested?

Not quickly. Uptake through the roots normally takes about 3 weeks, so the injection kit reaches active borers sooner.

Can one treatment be enough for an infested ash?

Not always. More than one application may be needed, depending on how heavy the infestation is.

Is fall too late to treat an ash?

No. Fall is one of the two ideal times for the drench, along with early spring.