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Progressive arborvitae dieback #807929

Asked August 25, 2022, 12:23 AM EDT

I submitted this question 7/27. I have yet to see any response. Thanks, Bob Dear Master Gardner Something is killing the Arborvitae on the NE corner of my house. I raised them from cutting of the previous plants that occupied this spot and grew too large after 25 years. This set was transplanted to this location summer 2019. 2020 they recovered from the transplant well. 2021 we had a drought and I watered them with a soaker hose daily (mistake). By fall the right plant was starting to shed leaves. By Christmas 2021 it looked similar to today. The next plant was just starting to show some brown Spring 2022. This spring I switched to drip irrigation running ever 4 days. As you can see the leaf shedding is now on all of the plants to varying degrees. Looking at you website, this has characteristics of spider mite, leaf blight, and pestalotiopsis. I haven’t seen any mites or eggs. I don’t see any signs of the leaf scales opening up to show anything inside. They just go brown. Likewise, I haven’t seen any spores. What am I dealing with? Is it possible to save any of the plants now? Is this contagious for any replacement plants in this location? Thanks, Bob Whitney 2520 166th Ave NW Andover, MN <personal data hidden>

Anoka County Minnesota

Expert Response

Hi Bob,

These arborvitae look like they’re showing signs of stress, not disease. The retaining wall is a difficult place for these arborvitae and I suspect they will continue to struggle. They’re tough plants but this location doesn’t give them much room and in winter with the elevation the arborvitae roots will go through cycles of freezing and thawing  which can lead to decline.

Though your previous arborvitae did well planted here our weather is changing. We have droughty summers and irregular snow cover, which is important for insulation when temperatures drop. In this raised location the roots of these plants have little protection from the big swings in temperature.

I’m sorry for all the care you’ve taken but this is not a location where these plants will thrive. 

Sorry you didn’t get a response before. Hope this helps.

MJ Replied August 25, 2022, 8:00 AM EDT

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