Spruce needle cast

Asked May 22, 2019, 4:23 PM EDT

I have a very large Colorado Spruce that is dropping green needles (in addition to the typical brown needles). I am attaching photos which I hope will be helpful. I have had three arborists diagnose it and now have three different opinions; I await word from a fourth and hopefully from you folks as well. First opinion: Tree is declining and is not treatable: Second: Rhizosphaera Needle Cast; Third: spruce bud scales. Would you like to comment or diagnose? I can send more photos if it would be helpful. Many thanks for whatever help you might offer! Patty Martinson

Hennepin County Minnesota scale insects spruce diseases rhizosphaera needle cast

3 Responses

It's possible that all three diagnoses are correct.

And here is a fourth: The samples shown in the photos are also affected by pine needle scale. Go here to learn about that and compare the small white patches on the samples to those shown at the following website:

We do not see any spruce bud scales on the samples shown in the photos. However, the scales are easy to overlook and may be present elsewhere on the tree.
Go here to learn about them and see what they look like:

Rhizosphaera needle cast may be present (it's very common) but we would have to see the tree onsite or sharp photos of the tree as a whole to render an opinion about that. Also, some other needle cast diseases resemble Rhizosphaera and laboratory analysis is often needed to identify them. Go here to learn about Rhizosphaera:

The long-term effects of unfavorable growing conditions, pests and diseases can lead to irreversible decline.

Although we don't know whether the tree in question is a Colorado blue spruce, much of the information in the following bulletin also applies to other spruce species:

If you aren't exhausted yet, information in the following diagnostic tool may be of interest.






Hi Bob,

Thank you for your comprehensive answer to my question. It seems to me that probably the first opinion was correct - that the tree is failing, probably on several fronts. I tried to take some photos but they didn't turn out too well. I had the tree trimmed up last year, so the bare branches are pretty recent damage. I hate to lose the tree, but I think it probably has to go - if you have a different opinion please let me know.

I truly appreciate your help, the websites you directed me to were quit helpful, and all the information helped put it in perspective.

Thanks again,

Patty

If many branches appear to be mostly dead or dying, it's probably time to let the tree go. However, without seeing the tree, this is just a generic statement.