eXtension

Norwegian Spruce Issue

Asked June 26, 2020, 3:18 PM EDT

I planted ten Norwegian spruce trees six years ago this summer. There have been no disease issues until recently. Regrettably, odd-looking brown knots have established themselves on every level of the horizontal branches. I have sprayed copious amounts of neem oil on the infected areas, but the oil appears to have no effect. What can I do to save my trees?

Spruce_300x300%2523

Cheboygan County Michigan

1 Response

Too bad you didn't sent pictures of the entire tree. Are these brown clumps present on all six of your spruces? To be honest, I've not seen this type of browning before.

While this is an unusual formation, it could be a clump of shoots (which would be an abberation) that have been attacked by Cooley spruce gall adelgids. Adelgids are insects that cause cone-like structures on new growth shaped like a cucumber. Adelgid feeding produces needle and shoot distortion and some yellowing. Galls appear early in the season as 2- to 4-inch cucumber-shaped growths. The galls are light green during late spring and early summer but dry out and become brown starting in mid-July. The galls often are mistaken for seed cones. Usually these critter are scattered on single shoots in various places on the tree rather than in a clump. I am unable to see a blown up image of your brown clump, so it's hard to tell.

If you can reach this clump, you should remove it if possible and examine it to see if it looks anything like the image below. There would likely be small holes where the insects have emerged (unless this is their first appearance). If you have dozens of these on every tree, it is likely something else. The links below provide additional information:



Plant Galls


If you can send pictures of the entire tree and also try to get a closer view of this mass of brown, I may be able to be more helpful. If you have these in every tree, you may wish to consult an arborist.

That is your best resource for diagnosing and treating your tree. An arborist is a certified and generally insured expert in trees and their problems. He or she can examine your tree and make recommendations regarding the health of the tree, any needed judicial pruning, and whether or not (in his opinion) it should be removed. You can find a certified arborist in your area here:

http://www.treesaregood.org/

Click on "Find an Arborist" at the top of the page; then click on United States from the pull-down menu. Then enter your State and City. This should bring up a list of certified arborists nearest to you. Or you may be able to locate one under "Tree Services" in your local Yellow Pages.