Fastigiate Norway Spruce tree damage - Ask Extension
Two years ago in the spring, I noticed the center top of this tree turning brown. I had a similar looking problem on another tree in our yard where I ...
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Fastigiate Norway Spruce tree damage #807863
Asked August 24, 2022, 3:45 PM EDT
Two years ago in the spring, I noticed the center top of this tree turning brown. I had a similar looking problem on another tree in our yard where I found white pine weevils... that was solved by trimming the infected section. I also trimmed and inspected the Fastigiate Norway Spruce 2 years ago, but did not find weevils under the bark. Trimmed it again this spring with the same result. I just trimmed the Fastigiate Norway a 3rd time, found small entry holes, but no bugs when I removed the bark. See photos. The first photo is overall view. Another photo of a piece is about 1 inch diameter. The third is of the infected trunk remaining on the tree (about 1.25 inch diameter).
Can the tree be saved? How do I treat the problem?
Jefferson County Colorado
Expert Response
Hi, Tim: thanks for contacting the Jefferson County Extension Plant Diagnostic Clinic.
The holes in the trunk and twigs of our spruce are consistent with the presence of an insect. As discussed in the attached CSU publication, pine sawyers can create the types of holes in your photos. Like white pine weevil, pine sawyers typically do not attack healthy trees but prefer those under stress, caused by drought or other sources of stress that can affect roots. Because spruce trees (which live in the mountains on north-facing slopes, which are cooler and wetter than where, for example, native pines grow), the location of this tree in a rock bed, may be stressful. It would be very important to be sure that the soil around the tree and its roots remains evenly moist, neither soggy nor dry, by probing with a narrow implement to a dept of at least 15-18 inches. And to be sure and water during the winter each month without an inch of moisture (a foot of snow). Inadequate water in spring, summer and winter can create the stress that predisposes spruce to insect infestation.
Other possible but less likely insects are spruce beetle and spruce ips (the latter damage is concentrated on the tops of trees); as discussed in the other CSU Fact Sheet, these beetles produce sawdust and pitch near feeding sites or at the base of trees and small round exit holes.
If adults or larvae are not seen (from which a specific diagnosis can be made), the pattern of larval galleries can help identify which insect is causing the damage in order to consider possible control strategies. It would be important to look for gallery patterns wherever you removed bark on the trunk and to look for galleries under bark on twigs with exit holes. If you see galleries, you can send more photos in reply to this e mail or, more helpful, bring samples you have cut off the tree along with the photos to the Jeffco plant clinic, 15200 West 6th Ave golden 80401,<personal data hidden>, Tuesday through Friday 8:30 - 4:30.
Colorado Insect of Interest (colostate.edu)
Ips Beetles - 5.558 - Extension (colostate.edu)
Pat B, Jeffco plant clinic master gardener
The holes in the trunk and twigs of our spruce are consistent with the presence of an insect. As discussed in the attached CSU publication, pine sawyers can create the types of holes in your photos. Like white pine weevil, pine sawyers typically do not attack healthy trees but prefer those under stress, caused by drought or other sources of stress that can affect roots. Because spruce trees (which live in the mountains on north-facing slopes, which are cooler and wetter than where, for example, native pines grow), the location of this tree in a rock bed, may be stressful. It would be very important to be sure that the soil around the tree and its roots remains evenly moist, neither soggy nor dry, by probing with a narrow implement to a dept of at least 15-18 inches. And to be sure and water during the winter each month without an inch of moisture (a foot of snow). Inadequate water in spring, summer and winter can create the stress that predisposes spruce to insect infestation.
Other possible but less likely insects are spruce beetle and spruce ips (the latter damage is concentrated on the tops of trees); as discussed in the other CSU Fact Sheet, these beetles produce sawdust and pitch near feeding sites or at the base of trees and small round exit holes.
If adults or larvae are not seen (from which a specific diagnosis can be made), the pattern of larval galleries can help identify which insect is causing the damage in order to consider possible control strategies. It would be important to look for gallery patterns wherever you removed bark on the trunk and to look for galleries under bark on twigs with exit holes. If you see galleries, you can send more photos in reply to this e mail or, more helpful, bring samples you have cut off the tree along with the photos to the Jeffco plant clinic, 15200 West 6th Ave golden 80401,<personal data hidden>, Tuesday through Friday 8:30 - 4:30.
Colorado Insect of Interest (colostate.edu)
Ips Beetles - 5.558 - Extension (colostate.edu)
Pat B, Jeffco plant clinic master gardener
Thank you for your timely, detailed reply. See the above photos for an update. I have removed the rock, as suggested. Landscaping cloth was removed for the area now covered in mulch. During this process, I found and filled 2 air pockets 3 inch dia, 6 inch deep in the root area. The damaged branches have all been near the tree top, with small round holes (see attached photos from a cutting today). This tree was planted 6 years ago.
Your opinion is appreciated. Would the tree benefit from insecticide? Also, let me know if it would be helpful to bring the samples to the plant clinic.
Best,
Tim
On 09/02/2022 12:16 PM Ask Extension <<personal data hidden>> wrot
Hi Tim,
Thank you for the additional photos. It is very helpful to see what's going on underneath the bark. Without actually seeing the insect or the larvae, I think it's best that you bring some samples in to our Plant Diagnostic Clinic for a closer look before making a diagnosis. The treatment methods may be different depending on what insect is causing the damage. Bring several samples of twigs or small branches with the holes and photos of the damaged area of the tree. And let us know if you saw any signs of sawdust around the trunk when you removed the rock.
Our address is 15200 W. 6th Ave., Golden, 80401. Our hours of operation are Tuesday - Friday 8:30-4:30. if you have any questions, or need more information about sample collection, you can call us at<personal data hidden>.
Hope to see you soon.
Lynne C.
Thank you for the additional photos. It is very helpful to see what's going on underneath the bark. Without actually seeing the insect or the larvae, I think it's best that you bring some samples in to our Plant Diagnostic Clinic for a closer look before making a diagnosis. The treatment methods may be different depending on what insect is causing the damage. Bring several samples of twigs or small branches with the holes and photos of the damaged area of the tree. And let us know if you saw any signs of sawdust around the trunk when you removed the rock.
Our address is 15200 W. 6th Ave., Golden, 80401. Our hours of operation are Tuesday - Friday 8:30-4:30. if you have any questions, or need more information about sample collection, you can call us at<personal data hidden>.
Hope to see you soon.
Lynne C.
