The American elm, Ulmus americana, is an important part of our natural and cultural heritage. The Iroquois and other Native Americans of the eastern woodlands favored elm bark for their long houses. In Colonial Massachusetts, elms were the original Liberty Tree, under which revolutionaries met; the elm remains the State’s official tree. Because of their graceful shape, rapid growth, and stress tolerance, American elms were the preferred and dominant shade tree planted in towns and cities of the Northeast beginning in the 1800’s. Elms were planted to create innumerable Elm Streets as settlers moved westward. For a fuller understanding of its historical significance see Tom Campanella’s Republic of Shade.

In 1931, shipments of infected elm veneer logs from France to Ohio accidentally introduced Dutch elm disease (DED) fungus into the United States. Within four to five years, scientists could trace the logs’ trip inland along the rail route; the death trail ran all the way to furniture manufacturers in Cleveland and Columbus. From there, the elm bark beetle further transmitted the DED fungus, Ophiostomo ulmi to the American elm throughout its natural range and progessively along streetscape plantings.

Since the 1940’s, mature American elms experienced rapid decline and now only 2-3% remain along public streets and roads. Generally, no public funds exist to take advantage of the best preventive measures that significantly reduce the chance of DED infection. Elm Watch with its Adopt-an-Elm initiative works to provide information and cultivate the financial resources needed to protect and steward these specimen trees in the Berkshire Taconic region of Massachusetts and Connecticut.

• Macro-injection is the only effective means of introducing fungicide to reduce the chances of Dutch elm disease. Arbotect injections on a two or three year repeat cycle is the typical preventive treatment. Alamo can occasionally be used at high dosage to reverse the disease, in conjunction with timely pruning of infected limbs. Micro-injection capsules do not provide the volume or distribution of fungicide necessary to protect the entire canopy.