Declining oak trees

There has been a pronounced decline of oak trees throughout our region in recent years. In many cases, it has been the chestnut oak that has been most impacted; however, other oak species have displayed these symptoms, as well, especially white oak and red oak. In many cases, the oaks have a thin crown and the leaves look off color. Many leaves throughout the tree or sections of the tree turn brown, but remain on the tree. The eventual outcome is that the entire tree or sections of the tree die. This condition has been identified in street trees and landscapes, as well as the forests throughout the region and beyond. This phenomenon is being widely studied by a number of scientists and pathologists, but no universal cause has yet been identified.

Plant health experts cite many reasons why this may be occurring. Standing water was present around oak trees for extended periods of time following a rainy 2018. Most oak trees occupy dry areas, and do not tolerate waterlogged conditions for very long. These overall wet conditions could have resulted in root rots or other diseases attacking oak trees. These diseases might be more pronounced in chestnut oaks or oaks that were stressed for other reasons, dense conditions of an overstocked forest, aging trees, or other underlining factors. Unseasonably cold temperatures in May of last year, right after the oaks and other trees were breaking bud may have resulted in leaf failure or in other conditions to manifest themselves. Perhaps the weakening of oak trees from these environmental factors made the tree more susceptible to disease such as oak wilt, bacterial leaf scorch, basal canker, root rot, and hypoxylon canker.

What can be done about this? In many cases, removing a dead or diseased tree to prevent additional infection is recommended. Another option is to monitor the site to see if it is spreading to nearby trees. In a landscape setting, it might be a good idea to consult a licensed arborist for recommendations on what to do with infected trees and how to help protect the remaining trees. In a forested condition, contacting a forester or other natural resource professional might be a good idea. Hopefully this wilting of oak leaves will be an isolated condition, due mostly to adverse environmental conditions; or the experts studying the phenomenon will determine the cause and formulate viable treatment options.

Article by FCFCDB

Photos credit: - Mike Kay

Nature note for 7/24/21