Garden Dilemmas, Delights & Discoveries, Ask Mary Stone, New Jersey Garden blog

Cover your Ash!

Mary Stone, Garden Dilemmas, Ask Mary Stone,Gardening tips, Garden Blogs, Stone Associates Landscape Design, Garden Blog, Ash Tree, Emerald Ash Borer

Hello fellow readers,

Recently I met with Andrea of Morristown whose property is graced with grand old ash trees one of which has died. Dave Dubee, arborist of Greenwood Tree, shared that while the dreaded Emerald Ash Borer is getting close to home, Andrea’s ash was not a victim but others should be protected.

Emerald Ash Borer (EAB), Agrilus planipenni, is an invasive wood-boring insect that kills all species of ash trees. EAB has been found in 5 counties in NJ, as close as Bergen and Somerset counties, and has invaded much of PA – 52 counties in fact and is now as close as Bucks County. It was first discovered in Michigan in 2002, likely imported from overseas cargo, and is now in 23 states.

Ash trees are found in a quarter of all forests and are commonly seen in landscapes, along streets, and in parks. Tens of millions of ash trees have been lost to this pest. While EAB beetles can fly a half mile, much of the spread is believed to be through the movement of infested firewood. There are now quarantine laws prohibiting firewood between counties and states to prevent further spread.

The adult Emerald Ash Borer is a half-inch long metallic green beetle with a copper red abdomen. Larvae of this beetle feed under the bark of ash trees which is what kills them. The inch-long larvae are white or cream and have ten bell-shaped segments. EAB adults emerge in May or early June creating D-shaped exit holes. They first infest the top of the tree’s crown which makes them hard to see. Woodpecker activity can be an initial sign and as EAB populations increase, crown dieback will occur. Trees will only live 3 or 4 years if untreated.

Mary Stone, Garden Dilemmas, Ask Mary Stone,Gardening tips, Garden Blogs, Stone Associates Landscape Design, Garden Blog, Ash Tree, Emerald Ash Borer

Ash Tree

Of the insecticides that can effectively control EAB, trunk injections work best. Specifically Emamectin benzoate, also known as Tree-age, which is injected into a tree’s vascular system. Because it is not sprayed on the bark or leaves, animals or insects that do not feed on the tree will not be affected. Research by Michigan State University on this product reports impressive results. Read more at:

Most effective insecticides are systemic and must be applied by a professional. However, there are protective cover sprays that homeowners may apply. But is the case of the invasive Emerald Ash Borer, it would be much wiser to do more than just cover your ash.

Garden Dilemmas?

Tip: There’s an official Emerald Ash Borer website,, created by authorities of our impacted states and Canada which provides continually updated information on the invader, advice on what you can do, and what authorities to contact should you suspect you have EAB.


Mary Stone, owner of Stone Associates Landscape Design & Consulting. As a Landscape Designer, I am grateful for the joy of helping others beautify their surroundings which often leads to sharing encouragement and life experiences. These relationships inspired my weekly column published in THE PRESS, 'Garden Dilemmas? Ask Mary', began in 2012. I dream of growing the evolving community of readers into an interactive forum to share encouragement and support in Garden and Personal Recoveries - seeking nature’s inspirations, stimulating growth, weeding undesirables, embracing the unexpected. Thank you for visiting! Mary

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