fir trees appear to be dying

Asked April 29, 2014, 12:47 PM EDT

i planted approximately 40 douglas fir trees 12 years ago from seedlings. they did very well(15 to 20 feet tall) until 2 years ago they started to become brown and the needles started to fall. I only have a few left that do not seem to be affected. I noticed in my neighborhood that the same thing is happening. is there some disease in the area. I live in Middlesex township. is there anything I can do to save them

Cumberland County Pennsylvania douglas fir fungal diseases

1 Response

Thank you for using eXtension. Our Cumberland County consumer horticulture educator, Annette MaCoy helped answer your question:
Douglas-firs in this area have been seriously affected by two fungal needlecast diseases, Rhabdocline and Swiss needlecast, which cause 2-year and older needles to turn brown and fall off. I see more of the Swiss needlecast than of the Rhabdocline. Once a leaf (needle) is infected, there is nothing you can do to “un-infect” the foliage, and new foliage will not grow to replace the needles that have fallen. If the trees have lost most of their needles, it may not be worth trying to save them. You can try culling the worst trees, to ensure good air circulation around the remaining trees; but this will not guarantee that the remaining trees will not become infected. The recommended treatment is to spray the trees in spring 2-3 times to prevent the just-emerging foliage from becoming infected, and you may need to do this for several years in a row. The recommended fungicide for homeowners is chlorothalonil, which is available under several different brand names, such as Daconil. If you choose to spray, you must read and follow label directions for application; and you must be able to provide thorough coverage of the trees. Because these trees are fairly tall, you may choose to hire a certified arborist to assess the condition of the trees and to spray for you. I hope this helps. Sincerely, Annette MaCoy

If you have any other questions, please contact our office at 717-240-6500 or CumberlandExt@psu.edu. You can contact Annette directly at ahm11@psu.edu.