Numerous tree care professionals in our area have become concerned about the number and relatively quick demise of mature (primarily white) oak trees in our area. This situation is occurring not only in the City of Takoma Park but in the entire DC Metropolitan Area and beyond.
Updated Resource – 09/11/19:
Bartlett Tree Experts – Factors of Oak Decline (White Paper)
by Dr. Kevin Chase, PhD, Entomologist
The first question being asked is why?
The short answer is climate change.
The more detailed answer involves the record amount of rainfall last year over an extended period of time, as well as earlier this year, which resulted in super saturated soils and areas that experienced elevated water levels. Tree root systems in these areas were damaged by low oxygen levels in the soil, resulting in root loss for many trees. In urban environments, the issue of heavy rainfall and saturated soils is compounded because the root area for trees is already limited by soil compaction, space, and other constraints. Also, the health of the trees that have died may not have been the best, to begin with.
Looking even further back to 2016 and 2017, there were very cold temperatures (in the teens) in the early spring after weeks of mild weather. This could have had an impact on the vascular system of the tree, impacting its ability to maintain existing root systems. These past injuries make a tree even more susceptible when periods of heavy rains or high temperatures take place. As time passes, the failing root system reaches a tipping point where the water needs of the canopy can’t be met leading to branch dieback and decline.
With the trees in a weakened state, other pathogens and insects (particularly beetles and borers) take advantage and are secondary contributors to the demise of the tree.
The heavy rainfall this year was followed by a period of intense high temperatures and periods of drought this summer. The stress of the heat and drought led to the already compromised large trees dying in very short periods of time.
One area of concern is that many of the beetles and pathogens in the dead tree can quickly spread to other trees around them. It is essential to have the dead tree removed off-site to keep the infestation from spreading.
Experts from the University of Maryland Cooperative Extension Service, US National Arboretum, the Maryland Department of Agriculture, the Maryland Department of Natural Resources and the US Forest Service have been contacted and there are efforts underway to better understand and document what is taking place.
What Can You Do for Your Trees?
First and foremost, you should have your trees evaluated every couple of years or as needed by a Licensed Tree Expert/Licensed Arborist. They can take a close look at the tree and its surroundings and diagnose possible problems and recommend a treatment plan. To find a Certified Arborist (Treesaregood.com)
If possible, while minimizing damage to root systems of large existing trees, try to improve your yard’s drainage, particularly in wet areas.
You may also want to add mulch (2-3” max) in a 6’ to 10’ radius around the trunk of a large tree. It is best to keep mulch several inches away from the trunk itself. Adding mulch around your tree provides vital nutrients and promotes macrobiotic activity essential for good soil.
Limit damage to a tree’s root system when mowing. It is better for the tree to create a mulched area around the trunk of a tree rather than grass.
White oaks, particularly hit hard this year, are an upland tree species. White oaks do not deal well with waterlogged soils. Therefore, when planting new trees, it is best to understand the species and its preferred growing environment. During dry spells, new trees especially need watering, particularly in the first 2 to 3 years after planting.
Visit our webpages for additional resources on Tree Care:
Resources
Plant new trees – Make a Difference!
City residents can take advantage of the City’s Fall 2019 tree planting program (print form here) with a check made payable to: City of Takoma Park, for the number of trees selected, plus tax = Total Order.
The following links are a helpful resource in selecting tree species:
The City offers assistance for tree removal of dead or hazardous trees for low- and moderate-income residents (85% of the median income for Montgomery County. The Emergency Tree Fund Criteria and Homeowners Application can be found here:
