With all of the recent buzz about the Asian Long-horned Beetle and the Emerald Ash Borer, many arborists are comparing these latest invasive insects to the most famous tree killer, the Elm Bark Beetle. The American Elm, at one time, was the most common street tree in most cities in the Eastern United States and the Midwest. Dutch Elm disease nearly eliminated one of America’s most beautiful and stately trees. McFarland currently takes care of approximately 20 to 30 American Elm trees in the Philadelphia area. Each is very rare and must be monitored regu- larly because of this disease, which can kill a tree in a few days, if it strikes at the right time and location. Our Success Story One Elm we care for is in the Wayne area. It is well over one-hundred-fifty-years old, a classic, beautiful American Elm that rises up like a vase and has a horizontal spread of over 100 feet.
During the summer of 2000, one of our employees noticed that a branch in the canopy of this tree was “flagging.” Essentially its leaves were drooping and turning brown in one small section, yet there was no sign of physical damage to the tree. McFarland’s arborist repre- sentative was called to the property and diagnosed the disease. An emergency crew was there within 24 hours. A large branch was removed back to the trunk and we immediately injected the tree with a systemic fungicide. We also sprayed the tree with an insecticide to kill any beetles that might still be present. It is very likely that the disease would have spread to the trunk and killed the tree within a week. Today, this tree is one of the largest and most beautiful Elms left in Southeastern Pennsylvania.