Shade tree disease control program
Branch death, or Flagging,at
multiple locations in the crown
of a diseased elm.
(Photo courtesy of Dr. Steve Katovich,
USDA Forest Service, St. Paul,MN.)
The city of Minnetonka’s shade tree disease control program protects the urban forest by identifying trees infected with Dutch elm disease and oak wilt. Removal and disposal of the infected trees prevents the diseases from spreading to healthy elms and oaks. Preventative injections and root graft disruption are also recommended in some instances. The program began in 1974 when Dutch elm disease that had infected and killed millions of elms east of the Mississippi river began to appear in Minnesota. In 1974 a total of 25 oaks and 26 elms were lost to disease in Minnetonka. In 1978, the peak year, Dutch elm disease killed 8,339 elms and oak wilt claimed 244 red oaks.
The city of Minnetonka forestry division provides consultation and inspection services to residents to diagnose and verify if an elm has Dutch elm disease or if an oak has oak wilt. Inspections occur between May 15 and September 1. Infected trees are marked for identification and our goal is to remove the tree within 20 days. The city of Minnetonka removes trees from public property only. Trees located on private property are the responsibility of the property owner.
In 2006, over 1500 tree inspections were conducted on public and private property by seasonal tree inspectors and the forester in order to identify elms with Dutch elm disease (DED) and oaks with oak wilt. There were 2,442 elms and 76 red oaks identified as diseased and marked for removal. Over 25 piles of elm wood were found on private property and marked for removal, since storing elm wood with bark intact (diseased or not) creates a breeding site for beetles that spread DED.
Beyond Dutch elm disease and oak wilt, there are hundreds of other tree diseases, insects, disorders, and environmental conditions that can lead to a tree’s decline. At this time, the city only requires residents to cut down elms and oaks identified by tree inspectors to be disease risks. The city forester can provide guidance to residents with tree disorders/diseases other than DED and oak wilt as time permits between May and September.
To request an elm or oak inspection from May 15–September 1, contact Minnetonka Mike or public works at 952.988.8400. If you are interested in a non-elm or oak related inspection or have a tree question, contact the city forester at 952.988.8421.
