Leaf Chlorosis on Willow Oak Trees in Towson

Asked September 6, 2018, 12:19 PM EDT

I belong to a group called the Green Towson Alliance that is dedicated to the beautification and preservation of trees and green space in the Towson area. We have noticed that there are a number (10 maybe) of willow oak trees along Bosley Avenue showing an alarming amount of chlorosis in the leaves. Arial photos show that the problem is only on trees along Bosley Avenue. We also noted that by Google Earth, the problem was occurring in 2014 or before. Some of the trees have a lot of dead wood. We have consulted with many arborists and others but would like to get more expert opinions. Some but not all of the trees are marked. Can you help? Thanks. Arthur

Baltimore County Maryland willow oak oak decline trees

1 Response

Willow oak trees are susceptible to scale insect damage, which could be a factor that is contributing to the chlorosis in the foliage. A good arborist would be able to detect scale insects. There are several types that can affect willow oaks.
There could also be abiotic (nonliving) factors at work, such as soil compaction, poor soil conditions, and/or air pollution damage. The following publication describes some of the abiotic problems that can lead to the decline of woody plants. https://extension.umd.edu/sites/extension.umd.edu/files/_docs/programs/hgic/HGIC_Pubs/Landscape/HG20...
A reputable certified arborist can collect samples from the trees to look for insects and test for pathogens. They also have techniques to amend compacted soil. We cannot do a thorough diagnosis just with aerial photos alone. Your best bet would be to work with a certified arborist.