WHO KNEW Hanover and the Dartmouth Campus Contain One of the Largest Collections of Mature Elm Trees in the Country?

Dartmouth College arborist, Scott Melendy, cautioned me to avoid the word “healthy” in my description. Healthy is a relative term. All US native elm trees are susceptible to Dutch elm disease which is spread by the elm bark beetle. Dutch elm disease is a lethal fungal infection and has devastated the elm tree population across the United States, as well as Europe.

Those of us who remember Hanover in the ‘60s and ‘70s will recall the stately elms that surrounded the Green. Sadly, the majestic DeWitt elm, which stood on the corner of the Green at the Hanover Inn intersection, was finally removed due to the increasing danger of limbs falling on cars or pedestrians. Scott tells me that if this elm tree had stood in a location isolated from vehicles and pedestrians, it could have continued living many years, thanks to the intensive treatment that the Town and the College give to the elms and, increasingly, to other native trees—like ash, beech, and hemlock—affected by invasive insects and disease.

I recently had a 10-inch diameter elm treated for Dutch elm disease. Smaller trees require a topical application of fungicide, but a larger tree can receive what amounts to an IV injection. A tree the size of mine, which stands a good 30 feet tall, can imbibe 18-20 gallons of fungicide in less than an hour. It will need to be treated again in three years. In addition, dead limbs—even those only an inch in diameter—must be trimmed so as not to provide points of entry for the elm bark beetle.

Some Hanover residents might feel inconvenienced by the closure of Crosby St., which runs behind the football stadium. However, it might make you feel better to know that the construction being done there, which is helping the College reach its net-zero goals by installing water pipes for geothermal heating/cooling, is in large part so as not to disturb the two “healthy” elms near the tennis courts.

It’s important to note that any work being done near trees can affect their health and cause them stress. These days, our trees are under near constant stress because of climate change which brings extreme weather. Too much water, like what we had this spring, or not enough water are equally stressful to trees, as are our milder and less snowy winters. Less snow means less insulation on the ground and less snow melt in the springs. Winter rain, followed by freezing, is also unhealthy for trees.

If you have elms on your property, or other native trees susceptible to invasive disease, please consider preventative treatment to help keep them healthy and vital members of our ecosystem.