As days grow warmer, residents shift walking routes to find cooler paths to their destinations. Some of Boston’s best shade is the deep canopy created by tall heritage elms in parks, along streets, and in yards throughout the city.
Every Spring, people strolling on Commonwealth Avenue see workers, hired by the Mall Committee, inoculating elms against Dutch elm disease.
Those little plastic vials, encircling the base of trees, contained a systemic fungicide. Inoculation is a costly step in a year-round effort to prevent the destruction of elms. A large tree costs nearly $500 per year for this treatment which must be repeated every spring.
With state land abutting city land it’s important that the state is also inoculating against the disease. “We do have about 35 elms that we have identified as worth saving in the urban parks area,” said Wendy Fox, press secretary for the Department of Conservation and Recreation. Some of those elms are on the Esplanade and in the Charlesgate parks.
Anyone who cares about trees, can join the watch to detect early signs of the disease. Spring is a good time to identify elms. The elms were the trees dropping the small, translucent circles with a visible seed inside. You know the ones- they float down like dry tan snowflakes and collect in gutters, on stairways, and on your dogs.
When we have a few days of hot weather, the elm bark beetle will come out of hiding and begin spreading the disease. That’s when volunteers look to the treetops for signs of distress. “We call it flagging, which is the yellowing of the leaves on a certain section,” said Greg Mosman, Boston’s city arborist.
If you spot this symptom or see yellowed leaves falling from an elm before foliage season, call the “Parks Line” at 617-635-7275. A detailed description of the location of the tree will bring out an expert to test it and determine a course of action.
Sadly, this may require the removal of the tree. “Sanitation and making sure that we eradicate the disease is what it is all about,” said Mosman. He explained that the possibility of the disease spreading is his worst case scenario.
Below is a photo of a tree that is pretty far along in the disease. Feel free to report much less damage than this. Efforts were made to save this one, but it did have to be removed to protect the trees around it. Two elms on the Mall were saved in 2007 because the disease was caught early enough to remove a portion of the tree and save the rest.
Twelve elms had to be removed from the Boston Common in 2007. More volunteer eyes are needed there to provide early warnings.
The latest report on the Commonwealth Avenue Mall’s trees is a good one. “In the 1960s, over half of its 600 trees were either dead or dying.” “The restoration was completed ... with the planting of 30 disease-resistant elms,” said Margaret Pokorny, chair of the mall committee.
Now, when you see those curious little vials around the trees, you’ll have a better understanding of the process.
And, the next time you take a walk in the shade you’ll be able to look up and check on the health of the trees and call in a report if necessary.
(An edited version of this article appeared in the Back Bay Sun and Beacon Hill Times.)
call the “Parks Line” 617-635-7275
More information on identifying and managing Dutch Elm Disease is available at:
If you would like to learn more about the history of elms, I recommend this book.