What is Oak Decline?

Written by: Keith Glaznap, Certified Arborist WI-0678A

Posted: 2018 | Consulting | Plant Health Care | Summer | Tree and Shrub Care

It was 1999 and I had just started my first college internship. My primary task was to perform a hazard tree assessment for the Parks and forestry department of a small city near my home. While beginning my work some of the street department crews joked that I should just recommend cutting down all of the Norway maple trees. When I asked them why, their reply was that most of these trees die from a disease called “maple decline”. I had never heard of this disease before so naturally I was curious.

When I returned to school that fall I asked my tree biology professor about this maple decline disease. He chuckled a bit and replied, “Maple decline is not a disease. It is a term that some people use to describe the decline of a large number of trees within a given species. The term usually implies that there is more than one agent causing the trees to decline and die.” This was the first time that I had been exposed to the idea that several agents could combine and contribute to the decline and death of a tree. As time passed I learned that there is rarely one simple cause for the death of a tree, there are frequently multiple agents or pathogens involved.

Fast forward to 2018 and it looks like our oak trees are now assuming the role of the maple trees that I observed during my internship nearly 20 years ago. There are so many oaks dying across the state that scientists have begun using the term “oak decline” to describe this phenomenon. As with the maples these oaks are often declining from multiple issues.

The initial stressor that some researchers feel is responsible for the decline of our oaks is actually a combination of many droughts throughout the late 1990’s and early 2000’s. These droughts consisted of dryer summers and/or a lack of snowfall during the winter months. Opportunistic insects and diseases took advantage of the resulting stress by colonizing or infesting the stressed and aging oaks. As the stress grew these opportunistic organisms began to gain momentum each year. The severe drought of 2012 may have then served as a tipping point as the number of oaks dying from these issues seemed to increase with no apparent end in sight.

If there are any oaks on your property that are important to you be sure contact your Certified Arborist today. We can help you to identify stress in your oaks and provide you with a management strategy designed to address any concerns that might be present. Once these trees decline to a certain point there is no coming back. Call today!