City Arborist and Trees & Greenery Committee Address Emerald Ash Borer Infestation

The Emerald Ash Borer (EAB), an insect that has plagued ash trees throughout the country, including New England, has arrived in Portsmouth. Sadly, the only way to try to control the infestation is to remove the damaged trees.

As City Arborist Supervisor Max Wiater notes, “In addition to EAB's destructive and invasive nature, it's important to understand how quickly an ash tree can become a hazard as the pest destroys the tree. It was determined to remove the trees with haste before a more serious hazard presented itself; the longer we wait the greater the hazard potential.”

The City’s Trees and Greenery Committee reviewed Wiater’s report and recommendations for several other ash trees on City property at their meeting June 14, 2023. (Agenda details which trees).

Last week the Portsmouth Public Library sent out this notice about the ash trees there: “If you’ve visited the library this week, you may have been saddened to see the stumps of several lovely tall ash trees. While it broke our hearts to say goodbye, these trees were sick with Emerald Ash Borer, an invasive and destructive pest. In these cases, it's important to remove trees quickly before they become a serious hazard. We are so grateful to our Public Works / Parks & Greenery Department for their excellent work in removing the trees, and for stump grinding later this month. We look forward to planting a new kind of tree in their place next spring. Meanwhile, certain areas of the second floor are seeing a little more sun! The library and the City are always changing, and we change with them.”

According to the National Arbor Day Foundation, from whom Portsmouth receives the Tree City Award and Tree Growth Award each year, the EAB, originally from Asia, is a bright metallic- green beetle that may be smaller than a dime, but it can take down ash trees thousands of times its size. Adults usually emerge in mid- to late-May from infestations to the trees during the previous year and lay eggs. The larvae bore into the ash tree and feed under the bark, leaving tracks visible underneath. The feeding disrupts the tree’s ability to transport water and nutrients, resulting in dieback and bark splitting. While there are an estimated seven to nine billion ash trees in the US, the emerald ash borer has destroyed 40 million trees in Michigan where the EAB was first discovered and tens of millions more trees throughout other states and Canada. Small trees can die as soon as one to two years after infestation, while larger infested trees can survive for three to four years. For more information go to: Emerald Ash Borer - The Arbor Day Foundation.