Arizona Cypress trees dying from trunk to branch tips - Ask Extension
We have two Arizona Cypress trees that were planted about 9 years ago. The trees are about 40 feet high now.
This was the first summer we noticed th...
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Arizona Cypress trees dying from trunk to branch tips #877390
Asked July 15, 2024, 8:49 PM EDT
We have two Arizona Cypress trees that were planted about 9 years ago. The trees are about 40 feet high now.
This was the first summer we noticed the trees looked like they were in trouble. Both trees seem to be dying from the trunk out to the branch tips and from the bottom much worse than the top.
We also made some landscape changes in the past few years. We live on a hill and installed a wall with a French drain at the base, and filled the gap between the wall to make more flat space. The trees are 10ft downhill of the new wall.
We also removed the 4GpH drip line each tree had, thinking that trees this mature don’t need additional water.
If this is a water issue, can we “rehydrate” the trees’ soil and save them? If it’s another issue, photos attached might offer some clues.
Benton County Oregon
Expert Response
Your intuition that the landscape changes you have made could be responsible for the decline of your trees is quite likely correct. A tree that is stressed - and this can often be seen on stressed conifers - often loses older (inner) foliage. Random branch die-back can also be a symptom of stress.
It could be a water issue. If I understand your description, the combination of the French drain and removing the irrigation line may have suddenly reduced the amount of water available to it. Even for a drought tolerant tree, this could be a shock, especially since we have been having increasingly hot summers. MANY plants that have been fine up until now are starting to suffer. Arizona cypress is moderately drought-tolerant, but not extremely so. And you have been watering it, so that is what it is used to.
In addition, the wall, and the backfill, is actually pretty close to the tree, and you may have smothered some roots under the backfill. Roots generally extend much further from trees than we think they do.
There are other possibilities, though. Is there any chance the French drain is draining water TO the tree - making the soil wetter? That could cause similar symptoms. Also, there are diseases that could possibly be present. I suggest you check the moisture of the soil. If you can get a long-probe soil moisture meter, you could check about 18" down. If not, dig a couple of holes at least a foot deep and see if the soil is very dry, very moist, or somewhere in between. If it is moist or wet you don't want to add any more water!
If the soil is indeed very dry, then yes, slowly re-hydrating it could well help. You won't see results immediately, but it could help the trees get through the rest of this summer without further stress.
Also, inspect the branches, both dying and healthy, for any signs of disease or insects. Anything that looks like it might be growing on it. If you find any, send pics.
Good luck.
It could be a water issue. If I understand your description, the combination of the French drain and removing the irrigation line may have suddenly reduced the amount of water available to it. Even for a drought tolerant tree, this could be a shock, especially since we have been having increasingly hot summers. MANY plants that have been fine up until now are starting to suffer. Arizona cypress is moderately drought-tolerant, but not extremely so. And you have been watering it, so that is what it is used to.
In addition, the wall, and the backfill, is actually pretty close to the tree, and you may have smothered some roots under the backfill. Roots generally extend much further from trees than we think they do.
There are other possibilities, though. Is there any chance the French drain is draining water TO the tree - making the soil wetter? That could cause similar symptoms. Also, there are diseases that could possibly be present. I suggest you check the moisture of the soil. If you can get a long-probe soil moisture meter, you could check about 18" down. If not, dig a couple of holes at least a foot deep and see if the soil is very dry, very moist, or somewhere in between. If it is moist or wet you don't want to add any more water!
If the soil is indeed very dry, then yes, slowly re-hydrating it could well help. You won't see results immediately, but it could help the trees get through the rest of this summer without further stress.
Also, inspect the branches, both dying and healthy, for any signs of disease or insects. Anything that looks like it might be growing on it. If you find any, send pics.
Good luck.
