Hi - I have a row of arborvitae trees along the back of my yard. Over the last 12-18 months, they have gone from healthy looking to near dying. Some are already dead, but I’m hoping to save the others if I can. They are turning brown, sometimes all over and sometimes only in parts. A small dogwood in the same area of the yard quickly lost all its leaves, turned black and died last summer. I thought it was from the drought, but now I’m not sure since these arborvitae looked much better at the end of the summer than they do now when we’ve had enough rain. Thanks in advance for your help.
Prince George's County Maryland
Hello. These types of symptoms are most likely weather-related. 2018 was an extremely wet year, followed by a very wet spring in 2019. Saturated soil can lead to the decline of fine roots. Then late last summer into autumn we had a flash drought. Roots that weren't lost to drowning and/or rot in the spring were overly-taxed come the drier autumn, and branch dieback resulted in some plants.
Evergreens can be notorious for not showing signs of branch death until much later than the damage occurred, so these symptoms are likely resulting from last year's problems.
The trees that are completely brown will have to be replaced. For those that have partial browning, you can prune out the dead areas and see if you are happy with what remains -- or replace them. Do not cut into old wood that does not have needles; it will not regrow.