What is causing this? - Ask Extension
We have this spruce tree in our yard that seems to be dying rapidly! 2weeks ago it looked fine. We have used Triaziide on it the last several years-...
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What is causing this? #866757
Asked May 02, 2024, 11:33 AM EDT
We have this spruce tree in our yard that seems to be dying rapidly! 2weeks ago it looked fine. We have used Triaziide on it the last several years- it had small green worms on the needles. Used again now, saw no sign of worms… What could be the cause, and is there a treatment?
Lake of the Woods County Minnesota
Expert Response
Without better photos I can only make a few guesses. One is winter burn:
https://extension.umn.edu/planting-and-growing-guides/protecting-trees-and-shrubs-winter
A second is yellow-headed spruce sawfly:
https://extension.umn.edu/yard-and-garden-insects/sawflies
For sawflies, it is especially important to be vigilant. Check the tree every day, and apply pesticides as soon as you spot them. Once they reach the stage where the tree is being defoliated, it is too late. The most effective pesticide for sawflies is humble insecticidal soap.
There are other possibilities. Look here:
https://apps.extension.umn.edu/garden/diagnose/plant/evergreen/spruce/
You could also send us two or three high-quality photos of the damaged area, especially in the area between the most serious damage and the area where it is still green.
https://extension.umn.edu/planting-and-growing-guides/protecting-trees-and-shrubs-winter
A second is yellow-headed spruce sawfly:
https://extension.umn.edu/yard-and-garden-insects/sawflies
For sawflies, it is especially important to be vigilant. Check the tree every day, and apply pesticides as soon as you spot them. Once they reach the stage where the tree is being defoliated, it is too late. The most effective pesticide for sawflies is humble insecticidal soap.
There are other possibilities. Look here:
https://apps.extension.umn.edu/garden/diagnose/plant/evergreen/spruce/
You could also send us two or three high-quality photos of the damaged area, especially in the area between the most serious damage and the area where it is still green.
