Brown crown on spruce tree
Hello, I have a young Black HIlls Spruce (4 years old) whose crown turned brown last year. I cut it back but now the branches below are brown. It looks otherwise healthy. We live in Glenwood at 6,000 ft. Do you know of any causes for this symptom? Thank you.
Garfield County Colorado
Thank you for using the Ask an Expert system.
Spruce trees can be hosts to multiple pests, including fungal pathogens, insect and mite pests, and additional environmental problems. That being said, it is difficult to determine the cause of 'browning' symptoms based on descriptions- as many pathogens can show similar effects on a tree itself.
The best way to get to the bottom of what is causing the crown to turn brown is to investigate the area of the tree that is transitioning (from healthy green needles to browning and yellowing needles). Investigate the bark and stems for any holes and damage, that may have lead to the decline.
Is there a way that you could upload pictures of your tree to this thread? A closeup of the transition area, and a picture of the entire tree. That would enable me to get a better visual of what is going on with your Spruce.
Good morning, Abi. Here are two photos, the top of the crown (I trimmed the dead parts back twice) and a picture of the top of the tree. Look forward to your insights! Have a great day.
Thank you for including such great photos!
Upon examining them, you appear to have a Spruce tree that has been attacked by a pest called White Pine Weevil.
These beetles show a very characteristic damage, resulting in the wilting and die-back of the central leader of the tree (you may have observed it to look like a Shepherd's Hook before cutting it back). This is further confirmed by a visible exit hole, from which the weevils emerge from the tree.
(I have included a copy of your picture, with the exit hole highlighted, for your information).
Here is a Fact Sheet on the White Pine Weevil, and the best management practices recommended for this pest:
The timing of pesticide application is a very important component of reaching effective control, and the recommendation is to utilize an appropriately labeled pesticide (containing the active ingredients: Bifenthrin, Permethrin, OR Cyfluthrin) during the spring, when the adult beetles will begin feeding on the trees and laying eggs- when daytime high temperatures are around 70 F.