Common Minnesota Tree Diseases To Look For On Your Property

Keeping your trees healthy is important for maintaining a healthy landscape. There are a number of common Minnesota tree diseases you need look out for in your trees. Some diseases effect the trunk and root system, while others effect the leaves in the canopy. Different species of trees are also subject to different diseases. Therefore it is important to know what kinds of trees are on your property, and what diseases might affect them. Let's take a look at some common Minnesota tree diseases and how to treat them. 

Common Minnesota Tree Diseases 


Anthracnose is a leaf disease resulting in numerous symptoms. These include brown and distorted leaf spots, blotches, defoliation, and twig cankers, among others. Anthracnose affects elm, green ash, sugar maple, and white oak trees here in Minnesota. If you notice brown, distorted spots on your trees' leaves, prune infected branches to allow air flow and light through the canopy, and raking fallen leaves off the ground. 

Black Knot 

Black knot is a fungal disease affecting numerous Prunus trees here in Minnesota. It is caused by Apiosporina morbosa. Black knot causes black swollen growths known as galls to grow parallel to stems and branches. If left unattended, galls can cause the trees' leaves and branches to wilt and die. Pruning is the most common form of maintenance; remove infected branches up to 4-inches away from the gall you are removing and bury or burn them away from the canopy. Fungicides can also be used to treat black knot. 

 Fire Blight 

Fire blight is caused by the bacteria Erwinia amylovora and most commonly affects apple and mountain ash trees here in Minnesota. The disease causes leaves and shoots to wilt; leaves turn brown and hang downwards, fruits turn dark and shrivel, and bark appears worn and cracked. Prune affected branches in late winter, and cut wood at least 8-inches below the visible symptoms. If pruning during the growing season, disinfect your tools with rubbing alcohol and a bleach solution and bury the removed branches. 

Tree Squad professionals are knowledgeable and experienced in handling many common Minnesota tree diseases. We will come out and inspect your trees and make a recommended course of treatment. Sometimes, if a disease has reached the trees trunk, the entire tree will die and need to be removed. Call and ask one of our representatives about scheduling a consultation or with any questions you may have today!