Tree Diseases in Michigan – Part 1

For the next several weeks, we are going to look at the various common tree diseases that we treat here in Southeastern Michigan through our sister brand, Safari Tree that specializes in Tree & Shrub healthcare.

Tree Cankers

 

Cankers are dead areas of bark that are located on the trunk, branches and/or twigs of a tree. Cankers are caused by numerous species of fungi that infect stressed or wounded trees, killing the living bark. Infected trees are characterized by discoloration, oozing sap, and sunken areas, cankers are some of the most difficult disease problems to manage. The best canker management is preventative. Keeping trees healthy and stress-free will reduce the risk of infection considerably. If a tree does have canker, the entire infected area should be removed, sterilizing the pruning tools between cuts. Pruning should not be done during wet or humid weather to minimize the spread of disease. Avoid wounding trees when doing yard work or mowing as this leaves the tree much more vulnerable to infection.

Oak Wilt Fungus

 

Oak wilt is a lethal disease caused by a fungus, which invades and disables the water-conducting system in white, red and other oak tree species. Different species of oaks vary in susceptibility to the disease. Red oaks typically die within 4 to 6 weeks of initial symptom development, while white oaks may survive or take 1 to 6 months to defoliate and die. Oak wilt is most often spread via root grafts between interconnected and grafted root systems. Root graft disruption and fungicidal treatments aid in preventing the spread of oak wilt.

How does oak wilt spread? Sap feeding beetles are the most common insect vector, but bark beetles have also been reported as a vector. They feed on fungal spore mats that form between the bark and the wood of the oak and carry oak wilt spores to wounds on uninfected trees. In the northern range, overland transmission takes place throughout the spring and early summer, while in the south it can occur any time of the year. Because beetle vectors (carriers) are attracted to fresh wounds it is important not to prune oaks during the season that spore mats are present. In the north, prune only during the dormant season; in the south, pruning is recommended only during December and January. Pruning paint is only necessary for wounds occurring during the growing season in the north, however, in the south, seal all wounds regardless of the season.

For healthy trees, contact one of our Certified Arborists today to learn more about our preventative treatment plans.

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