Maryland's Identification Guide Works

By Benton Hall
Office of Environmental Design
Maryland State Highway Administration

Maryland's Office of Environmental Design produced this laminated guide.

In June, 2000 the Maryland State Highway Administration, Office of Environmental Design initiated an effort to manage the exotic and invasive tree Ailanthus altissima. The Ailanthus altissima, which is ironically called the Tree of Heaven, has become a major problem on highway roadsides in Maryland, primarily in the central and western parts of the state. Ailanthus is an aggressive competitor that moves into disturbed areas, rapidly displacing native plants and colonizing large stretches of roadside. The Ailanthus trees have virtually no commercial, aesthetic or wildlife value.

non-native wildflowers draw attention to a significant historic site on MD 12.

Wildflower signage enhances awareness of traveling public and maintenance crews.

The management plan for Ailanthus called for the chemical treatment and removal of colonies of Ailanthus in order to create areas for reforestation with desirable native species. The treatment strategy closely followed guidelines for Ailanthus management that were developed by the Maryland Department of Natural Resources, Forest Service. The technical information from the Forest Service was accompanied by permits that allowed the removal of the Ailanthus trees from the publicly owned rights of way. A condition of these permits was that the crews engaged in the spraying of Ailanthus must be able to differentiate between Ailanthus and similar looking but desirable native trees, such as Sumac. The Office of Environmental Design developed a training course and provided instruction to the contractors and state forces that would be involved in the management program. The Identification Guide was an integral part of this training course.

The approach that was used for treatment was a basal application of Pathfinder II herbicide. The Forest Service recommendations indicated that the best time for application is June through September. Contractors and state forces performed basal applications from June through September, 2001 in five counties covering an area of 42 acres. Most of the applications were concentrated along the I-70 corridor in Frederick, Carroll and Howard Counties. Additional areas were treated in Baltimore and Harford Counties. After a period of 90 days, the treated trees can be cut and chipped. Additional foliar treatments were performed once the window of opportunity for basal application had expired. A total of 15 additional acres were treated using foliar applications of the herbicide Escort. Throughout the Fall of 2001 and Winter of 2002 contractors and state forces will be cutting and chipping trees that are located in areas that are targeted for eventual reforestation. We do not anticipate having 100% control after one application, and follow up treatments will be made during the spring, summer and fall of 2002.

The program for Ailanthus management that has been developed and put into action by the Office of Environmental Design represents a cooperative effort between different elements within the State Highway Administration, contractors and the Maryland Department of Natural Resources, Forest Service. The foundation that has been laid by this management program can hopefully serve as a model for developing other management efforts to deal with the growing list of invasive species that are overtaking our roadsides.