Oak and elm tree pruning advisory

Posted May 10, 2005

Because of disease transmission (Dutch Elm Disease and Oak Wilt) these trees should be pruned when they are inactive. Therefore December, January and February are the best months to prune elms and oaks. This is also a good time to prune other shade trees.

If you must trim your elms and oaks at other times of the year, follow these suggestions to minimize the chances of disease transmissions:

High risk: April 1 - July 15 Prune only storm damaged elms and oaks: treat wounds with a tree wound dressing (tree paint).

Reduced risk: July 15 - September 1 Treat all elm wounds with wound dressing: oaks do not require treatment.

Low risk: September 1 - March 31 Can do all elm and oak pruning without applying wound dressing.

Understand that these dates are not "set in concrete." Temperature and moisture can affect when trees should or shouldn't be pruned.

For more information contact:

Paul Edwardson, Parks Manager
1700 W. 98th Street
PH: 952-563-8762
E-mail:pedwardson@ci.bloomington.mn.us