Help with Giant Arborvitae - Ask Extension
I'm hoping that you can give me some advice on my two Giant Arborvitaes that appear to be very sick. I planted them about 3 years ago and they have do...
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Help with Giant Arborvitae #868224
Asked May 13, 2024, 2:49 PM EDT
I'm hoping that you can give me some advice on my two Giant Arborvitaes that appear to be very sick. I planted them about 3 years ago and they have done very well up until now. As you can see from the attached pictures they are both discolored and the bark on the trunk is cracked. Please let me know if you have any recommendations to save them?
Livingston County Michigan
Expert Response
Hello Gordon -
I have a question for you. Are the cracks in the bark on the south side of your tree? If so, I believe you have some frost cracks. Here is an article for you about them: https://sites.udel.edu/planthealth/2014/01/31/winter-injury-and-frost-cracking/ It's difficult for me to tell what the browning is from. It could be that we are having a dry spring thus far, from over fertilizing, or from salt damage. It could be from one of the following diseases that is found on arborvitae. Here is a link about them: https://ag.umass.edu/landscape/fact-sheets/arborvitae-needle-blight
If you want to see if your trees have one of these pathogens, you can get have it checked at the MSU lab for a small fee. https://www.canr.msu.edu/pestid/submit-samples/
I hope this helps you and your trees.
I have a question for you. Are the cracks in the bark on the south side of your tree? If so, I believe you have some frost cracks. Here is an article for you about them: https://sites.udel.edu/planthealth/2014/01/31/winter-injury-and-frost-cracking/ It's difficult for me to tell what the browning is from. It could be that we are having a dry spring thus far, from over fertilizing, or from salt damage. It could be from one of the following diseases that is found on arborvitae. Here is a link about them: https://ag.umass.edu/landscape/fact-sheets/arborvitae-needle-blight
If you want to see if your trees have one of these pathogens, you can get have it checked at the MSU lab for a small fee. https://www.canr.msu.edu/pestid/submit-samples/
I hope this helps you and your trees.
Thank you very much for this information!
I did check the cracks on both Arborvitaes and they are on the south and southwest sides of the trees. Hopefully they heal on their own.
Regarding the needle blight, I think it is likely that they have a pathogen. Would you recommend that I prune the needles on the parts that are infected? Or would it be better to treat them with something?
Thanks,
Gordon Smith
Hi again Gordon -
I'm sorry about your frost cracks. They should heal, but if you need to prevent them, there is some paper "tape" that you can wrap around the trunk of the tree to protect it in winter. With an evergreen, that might be challenging work, though.
We like to know what we are dealing with before making recommendations, but according to this link: https://extension.psu.edu/arborvitae-diseases both diseases seem to be treated in the same way. I would trim off the brown fans carefully, and discard them away from the trees. You could use a fungicide which could help in your situation.
Good luck!
I'm sorry about your frost cracks. They should heal, but if you need to prevent them, there is some paper "tape" that you can wrap around the trunk of the tree to protect it in winter. With an evergreen, that might be challenging work, though.
We like to know what we are dealing with before making recommendations, but according to this link: https://extension.psu.edu/arborvitae-diseases both diseases seem to be treated in the same way. I would trim off the brown fans carefully, and discard them away from the trees. You could use a fungicide which could help in your situation.
Good luck!
