An American elm tree more than a 100 years old was cut down on July 20. The American elm previously located at 1615 Greenleaf St. was infected with Elm yellows (EY) and Dutch elm disease. EY is caused by phytoplasma, a form of bacteria, infecting the elm’s inner bark and roots. EY tends to crop up in mid to late summer. The symptoms of the disease are leaves curling at the margin before turning yellow, then brown before falling off. The infected elm’s inner bark will have a wintergreen smell, and will begin to yellow along with developing brown spots.
Dutch elm is caused by a fungus and shares many symptoms with EY, such as leaf discoloration and occurring primarily in the summer. Unlike EY, Dutch elm does not discolor the entire crown of a tree and does not discolor the inner bark of the tree. Assistant Director of Public Works and Forestry, Paul D’Agostino said, “It’s impossible to say how [elm yellows] got here. It was mostly likely spread by leafhoppers.” Mr. D’Agostino said that a number of trees are infected every year with Dutch elm and EY, “especially private trees,” Mr. D’Agostino added. The City inoculates its trees to protect against Dutch elm. Mr. D’Agostino said there is currently no way to protect against EY besides spraying it with pesticide which can be just as deadly. EY could pose a threat as the City continues its “I Heart Evanston Trees,” movement to replace fallen trees in the City.