What is the disease? - Ask Extension
We have notice many of our pine trees are suffering from the same disease. And wonder what we can do for them. (Many trees in the neighborhood are s...
Knowledgebase
What is the disease? #579946
Asked July 14, 2019, 1:37 PM EDT
We have notice many of our pine trees are suffering from the same disease. And wonder what we can do for them. (Many trees in the neighborhood are similarly infected.) The three images: 1) close up, 2) a little back, 3) the tree (close up branch is on the bottom right).
Conifer CO, 8600 feet elevation.
PS... The answer is: Western Spruce Budworm.
see: https://csfs.colostate.edu/media/sites/22/2017/06/csfs-the-budworms-are-back-synopsis-june-2017.pdf
We visited the local Forest Service office and they provided the above answer and PDF.
Jefferson County Colorado
Expert Response
Hello,
Thank you for your question. Yes, Western Spruce Budworm affects both native fir trees and spruce trees. The trees in your photos are Fir trees, likely Douglas Fir (Pseudotsuga menzezii).
An integrated approach to control is recommended.
The USFS document you were given by the Forest Service: https://csfs.colostate.edu/media/sites/22/2017/06/csfs-the-budworms-are-back-synopsis-june-2017.pdf
CSU Fact Sheet on Western Spruce Budworm: https://static.colostate.edu/client-files/csfs/pdfs/05543.pdf
Best regards,
Thank you for your question. Yes, Western Spruce Budworm affects both native fir trees and spruce trees. The trees in your photos are Fir trees, likely Douglas Fir (Pseudotsuga menzezii).
An integrated approach to control is recommended.
- Let natural predators do their work...that is, don't apply chemicals unti other strategies have been tried and the trees are infested for 3-4 consecutive years. Oubreaks do tend to be cyclical.
- Thin your stand of trees to create a less-hospitable environment for western spruce budworm. An open forest setting, where tree crowns do not touch and the height of the tree canopy is fairly uniform is less supportive of outbreaks. A good rule of thumb for ideal tree spacing is to multiply tree diameter in inches by 1.5 to determine the desired number of feet between tree trunks. (Thus a 12-inch diameter tree should be at least 18 feet away from the trunk of the nearest tree.)
- Chemical controls can be considered after 3-4 consecutive years of significant defoliation of high-value trees.
- Timing is everything: spray just after the bud caps come off the tree tips and the new tips and needles begin to expand.
- Effective control of spruce budworms feeding on a tree requires that nearly all the foliage be covered with the insecticide.
- Insecticide options are listed in the USFS publication that you sent me.
- A licensed arborist could do this for you. If you don't have one, use the "Find an Arborist" tool at www.isa-arbor.com.
The USFS document you were given by the Forest Service: https://csfs.colostate.edu/media/sites/22/2017/06/csfs-the-budworms-are-back-synopsis-june-2017.pdf
CSU Fact Sheet on Western Spruce Budworm: https://static.colostate.edu/client-files/csfs/pdfs/05543.pdf
Best regards,
