Managing Beetles to Preserve Elm Trees


American Elm removal Commonwealth Avenue Mall June 17, 2014
A Commonwealth Avenue Mall Centenarian is removed due to Dutch elm disease (2014)

The Friends has been funding the expert care of trees since 1970 as part of our mission to preserve and enhance the Boston Common, Public Garden, and Commonwealth Avenue Mall. This work would not be possible without the financial support of our Members. We are always delighted when Members express a genuine interest in learning more about the details of the work we do. We noticed an increase in questions about tree care coming in over the past few months, and in particular inquiries about our work related to the elm bark beetle and Dutch elm disease, which seem to have been sparked by our Members Reception presentation (Digging In: Beyond the Roots of Urban Tree Care). We asked our contractor Christine Helie to explain some of the work she does for us. She is an entomologist and field scientist who works with her husband Normand at The Growing Tree.  Chris is directly involved in developing an Integrated Pest Management program to preserve the mature and young elm trees in our parks. Here is what she had to say:


Among the trees in the Public Garden, on the Boston Common and on Commonwealth Avenue, is a unique collection of elm trees. This valuable assortment of European, American and Asian elms are susceptible to Dutch elm disease (DED). This disease is caused by a fungus that compromises the conductive tissue of the tree and eventually kills it. The primary vector of the fungus is the European elm bark beetle. Through its breeding and feeding behavior, this bark beetle transfers DED from diseased trees to healthy trees.

In 2012, with the support of Greg Mosman, Tree Warden of the Boston Parks & Recreation Department and on behalf of the Friends and its tree care program, a monitoring and management system for this insect was designed as part of a new elm tree preservation program for the mature and young elm trees in the three parks. The manner in which insects are monitored and managed can vary depending on the habitat in which they exist. For our purposes, a three sided box of plywood, painted green was built to house an 18”x25” sticky trap with a pheromone lure attached in the center.

Pheromones are chemicals produced by an organism that elicit a response from another organism. They are used by insects or animals to communicate with individuals of the same species. Depending on the type of activity, different pheromones will be used to relay a message.

For example, ants use a trail pheromone to mark a path leading to food that other ants in the colony can find and follow. However, when encountering a dangerous situation they use an alarm pheromone to warn their nest mates. The pheromones used in our beetle traps signal to both male and female elm bark beetles that this is a great spot for breeding and laying eggs.

There are over 24 traps in use throughout the parks. From the beginning, our goal was to

Beetle counter, PG, May 23, 2014, EAJ
beetle trap

make them easy to access but discreet. Rather than placing unsightly posts throughout the parks, we decided to install our traps on trees at least 150 feet away from any elm trees.

Because the bark beetle is attracted to elm trees weakened by stress, one of the components in the pheromone mimics volatiles released by a stressed elm tree. As a result, the trees that we chose to place our traps on became substitute elms, luring the elm bark beetles away from the elm trees.

Pheromones are effective at very low concentrations and insect specific. This fact becomes evident when you compare some of the trees with traps to an actual elm tree. The vase shaped elm tree with upright branching is quite different from the pyramidal shaped Norway spruce with drooping branchlets.

The elm has a broad leaf with a serrated edge, whereas the spruce has needle-like foliage. The bark of an American elm tree has deep crevices that form diamond-shaped furrows, while the bark of a Norway spruce tree has thick round scales.

Regardless of these features though, the Norway spruce in the Public Garden has consistently captured high numbers of the European elm bark beetle on its trap.

Below are images showing the physical differences between Elm trees (top photos) and Norway Spruce trees(bottom).

Bark beetles appear to use different methods when locating a proper host tree. By crawling on the bark, they can sense the texture and determine whether the tree is susceptible to attack. Dispersing beetles are also guided by odors from weakened trees. From what we have observed in our program, it seems apparent that when the beetles land on a potential host, one of our stand-in elms, the odors detected override the physical clues they pick up from the tree. As a result the beetles continue to search for the source of the pheromones until they are caught on the trap or die trying to find the “elm.”

These traps have also allowed us to monitor the location, concentration, and pattern of movements of this disease host, helping to indicate the optimal times to treat, prune and, in some cases, remove a diseased tree.

Since their implementation, the elm bark beetle traps have become important tools in our fight against Dutch elm disease. The twenty four traps in use throughout the parks and surrounding areas are installed on thirteen different tree species. While these trees may be Oaks, Locusts, Maples, Lindens, or even a Norway spruce, they actually serve as substitute elms and are important allies in the preservation of our real elm tree population.

Landolt, Peter J. “Sex Attractant and Aggregation Pheromones of Male Phytophagous Insects.” American Entomologist Spring 1997 12-22. Print.

Anne Mostue: Walking into Blossoming Volunteer Opportunities

Friends Rose Brigade co-leaders Carl Foster and China Altman with Anne Mostue (right)

Anne Mostue became a Member of the Friends of the Public Garden in 2013 when she moved back to Boston after several years away. She was born here and grew up nearby. Boston radio listeners may find Anne’s name (and voice) familiar. She works as an anchor for Bloomberg Radio in Boston, 1200 AM and 94.5 FM HD-2. Previously, she was an on-air reporter/producer for WGBH, the NPR and PBS station airing in all six New England states.


We asked Anne how she became aware of the Friends of the Public Garden and this is what she told us: “I learned about the Friends when I became a volunteer rose gardener! One day I was walking through the Public Garden, admiring the flowers and missing the garden I had when I lived in Maine. It occurred to me that the city might need help, and wouldn’t that be an ideal volunteer opportunity? I made a few calls and found China Altman, who leads the Rose Brigade.”

The Friends of the Public Garden works in partnership with the city to care for the Common, Garden, and Mall. The volunteer Rose Brigade has worked for 28 years to care for the roses, including planting new bushes and weekly pruning, deadheading, and clean-up of beds. Anne says, “Working in the beds every week actually feels like an escape from the city. We’re dirty and completely absorbed in each bud and bush. I look forward to my time in the garden all week.”

Anne started with the Friends as a Rose Brigade volunteer and then began attending Friends events including those hosted by our Young Friends group. She has become a very active park steward who now also serves on our Council, and recently became co-chair of the Young Friends group.

We asked Anne to share something that she has learned from working with the Friends. She says, “People might be surprised to learn that the city can only do so much, so volunteers step in – to garden and also to advocate for the open space and its preservation.”



Message from Board Chair Anne Brooke

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Anne Brooke thanking Members and supporters at the 2015 Summer Party (Photo: Piece Harman)


Dear Friends,

It has been a wonderful year for the Friends and our three treasured greenspaces. Our work in 2015 has brought so many plans and projects to life that have improved the Boston Common, Public Garden, and Commonwealth Avenue Mall. One might say that how it all comes together is magical, and sometimes it feels that way, but it is actually the efforts and generous support of many individuals that make it possible.

Thank you to my fellow Board members, our dedicated Members, volunteers, donors, and our talented Executive Director and staff. Each of you makes a difference in all that you do.

You are these parks’ greatest supporters and advocate voices. Because of your contributions, more than $1 million was invested in parks care and programs in 2015, the restoration of the Garden’s George Robert White Memorial fountain will break ground in the spring of 2016, 10 trees and three benches are newly sponsored, and so much more.

We kindly ask that you continue your stewardship by renewing your Membership before the end of the year, inviting friends to join, and delighting someone with a gift of Membership.

We look forward to working together with you in the new year to continue raising the level of excellence in these three greenspaces we care for in partnership with the City. As you know, it takes a great deal of work, advocacy, and money to maintain and improve them; and sometimes a little magic, too. You are the magic that makes it happen and we can’t do it without you.

Wishing you a happy and safe holiday season,

Anne Brooke

Chair, Friends of the Public Garden

Honoring Our 2015 Tree and Bench Sponsors

Photo: Elizabeth Jordan

Thank you to our 2015 tree and bench sponsors for supporting our parks!

  • Sloane Fellows Class of 2000 in memory of Yoshi Baba
  • McKey W. Berkman
  • Barbara and Julian Cherubini
  • Janet J. Fitzgerald
  • Jared Gollub
  • Christine and David Letts
  • Anita Lincoln
  • Committee to Light Commonwealth Avenue Mall in honor of Mimi LeCamera
  • The Family of Werner A. Low
  • Margo Miller
  • Scott Thatcher and Nawamas Chumowart
  • Sherley Gardner Smith
  • Lynn Wiatrowski-Madsen

The Boston Common, Public Garden, and Commonwealth Avenue are greenspaces steeped in history. They are important places where we honor the history, culture, and milestones of our nation, city, and neighborhood with sculptures and memorials. Famous people and events are recognized with statues, tablets, and other displays. And as much as these three greenspaces serve as a place to honor some of the most public figures known to us, they are also a place where individuals celebrate special people or events in a very personal way by sponsoring a tree or bench in their name. The next time you stroll by, read the plaques and ponder the stories of people and events they represent.

For information about the Tree and Bench Sponsorship program in the Common, Garden or Mall visit our website.


Sprouts and suckers… and we’re not talking about alfalfa and lollipops.



To the untrained eye, root sprouts and tree suckers may appear to be signs of nature doing what it is designed to do, but if you ask the experts, as we did recently in a conversation with our consulting arborist Norm Helie of The Growing Tree, it depends on the tree and where it is.

Sprouts and suckers occur naturally in almost all tree species and are part of the survival mechanism to help trees dominate a given area. According to Helie, more than 60 percent of forest regeneration in New England is from root suckers. In addition, trunk sprout growth helps trees naturally recover from catastrophic snow, wind, and ice events.

In the urban environment root suckers are more prolific than in nature and can be a response to certain stresses, such as insects or disease. Hearing Helie explain his observations and treatment regimens for the sprouts and suckers on trees in the Boston Common, Public Garden, and Commonwealth Avenue Mall, it sounds similar to how a dermatologist might describe treating growths found on a human body.

Root sprout growth takes energy from the tree and diverts it from the main trunk, which can then contribute to further decline. Proper removal involves removing as much of the cells that keep the sprout growing, called the meristematic tissue, as possible. The remaining tissue needs to be cauterized in order to inhibit new sprouts. Follow-up care is certainly needed to prevent new sprout growth, along with fertilization and disease control for overall health.IMG_1169

The next time you see a tree that appears to be struggling in our urban greenspaces, pause and see if sprouts and suckers are part of the problem. Helie says, “these trees always look like the best thing you can do is to cut them down but, in fact, these trees need attention and can do well with the right kind of care.”

Learn more about the Friends tree care program.


Photos: Norm Helie





Meet Michael Fenter: Park Stewardship in Action

Michael Fenter

Michael Fenter has been a Member of the Friends of the Public Garden since 2010. He learned about the Friends through Board member Margaret Pokorny when they were working on community projects together. The Mall is special to Michael and he considers it to be his “front yard”. He has lived in many cities and believes there is nothing quite like the parks in Boston. He enjoys seeing the seasons change in them and says, “the parks are an ever-changing living canvas of nature right in the middle of modern living.”

The parks mean so much to Michael that he has helped care for them by volunteering in a variety of ways for Mall projects, including fundraising efforts for a sponsored tree in memory of people who died from AIDS and ongoing litter and graffiti clean up. He also participates in his employers’ match program, ensuring that his contributions and volunteer hours go even further with a match from Microsoft.  He explains the Friends and sometimes hands out informational materials, as he responds to people’s questions while volunteering or walking his dogs along the Mall

“One way to enhance and restore these parks is to educate the next generation of stewards,” says Michael. He started an annual “Keeping It Clean” day for his nephews’ school where the children come and clean litter on the Mall from Arlington Street to the Kenmore block. They are rewarded with pizza and bowling for their volunteer hours! He believes these parks are a legacy for past and future citizens to treasure. “The main reason to join the Friends is because it is our responsibility to preserve these living treasures for the next generation,” he added.

Boston Common Receives Lime Treatment


The white dusting appearing on the grassy areas of Boston Common over the next few days is not made up of snowflakes that we traditionally expect to see this time of year. Warmer temperatures have made it possible for us to fit in one more needed treatment to help trees, turf and soil on the Common. The treatment will support better root growth and development, provide plant nutrients, increase disease resistance, and correct several conditions that are causing additional stress on the plant life in this heavily used urban park.