What could be wrong with this tree

[Jonathan Problemtree]

Hello,

In my backyard, I have two trees of the same type. They are about 10 meters from each other; one looks quite happy while the other appears to be having problems.

The happy tree:


The sick tree:


The sick tree had leaves on it just three months ago. I am located in San Francisco; this is our dry season, so most large plants are expected to rely on their roots' access to groundwater. In my particular location, the water table is typically not very far from the surface.

Can anyone help me to figure out what is wrong with this tree? Are there particular spots that I should take pictures of?

 

[TNTreeHugger]

How tight is that wire tie around the trunk?

 

[Jonathan Problemtree]

How tight is that wire tie around the trunk?

Thank you for the reply. The ziptie is quite loose around the bark of the tree.

 

[TNTreeHugger]

Thank you for the reply. The ziptie is quite loose around the bark of the tree.

Well, it can't be that then.
I'm not a tree expert, just trying to help until an expert comes along.

The leaves on the happy tree look like they may have some kind of spots on the ends?
What kind of trees are they?

 

[BC WetCoast]

It's an ash, but I can't figure out which species. The closest I could determine was an Arizona ash. Someone with more California experience will know better.

Did the leaves just fall off? Did they wilt from the tips in? Did the leaves look like they were being munched on?
Has anything changes in your garden ie moved plants, painted back wall, added stone facing to your house etc

Have you checked the water level below the tree? The soil looks dry on the surface, but that can be deceiving.

 

[unclemoustache]

Ash? I was thinking willow.

 

[TNTreeHugger]

Not a Russian Olive?

 

[BC WetCoast]

I thought olive and willow at first glance as well, but then notice the opposite leaf arrangement.
The only trees that have that are:
MAD Cap Horse - Maple, Ash, Dogwood and Horsechestnut. The Cap being Caprifoliaceae which are mainly shrubs like honeysuckle.

 

[TNTreeHugger]

Umbellularia californica?

 

[BC WetCoast]

Alternating leaf structure, whereas the OP's is opposite.

 

[TNTreeHugger]

Actually, they look whorled to me... with white flowers?

 

[unclemoustache]

better pics of the leaflets would help, but the question is about health rather than ID, but I'm more interested in ID than health, since it isn't my tree.

 

[TNTreeHugger]

better pics of the leaflets would help, but the question is about health rather than ID, but I'm more interested in ID than health, since it isn't my tree.

Me too.

 

[JeffGu]

...so most large plants are expected to rely on their roots' access to groundwater...

Did you explain this to the trees? Did they agree to the plan? From the looks of that bone dry dirt, I think they might be thirsty. If it didn't leave a suicide note, I'd try watering them.

 

[TNTreeHugger]

It's an avocado

 

[TNTreeHugger]

 

[Jonathan Problemtree]

Did you explain this to the trees? Did they agree to the plan? From the looks of that bone dry dirt, I think they might be thirsty. If it didn't leave a suicide note, I'd try watering them.

Thank you for all of your responses.

I had been away for a little while, so I didn't get to see how the leaves were lost. I doubt that they were taken by insects, though.

Last year, our weather was extremely dry. Because of this, I watered my trees using a drip system that delivers a deep watering over the course of 2 hours, at night, every 3 days. I turned this system off because spring of 2016 had been unusually wet.

(My various plants and trees had been perfectly fine reaching groundwater in other years.)

When I noticed the state of the tree (a week ago now?), I gave it a deep, manual watering. It also got automatic watering afterwards. I have yet to see any change.

As for the ID, I don't know what kind of tree it is. I'm pretty sure its not avocado; my neighbor has one and they look nothing alike.

 

[treesmith]

Looks like a buddleia to me from the picture, can't say for sure though

If it is you can chop them to ground level every year to keep them vigorous, or they get leggy, weak and can decline

 

[Jonathan Problemtree]

Did you explain this to the trees? Did they agree to the plan? From the looks of that bone dry dirt, I think they might be thirsty. If it didn't leave a suicide note, I'd try watering them.

The tree has now been getting regular water for two months but still looks the same. Its "cousin" elsewhere in the yard is doing wonderfully.

To recap, this tree got no intentional watering for 3 months. Everything else in the yard did fine, but this tree lost all of its leaves. Another of the same species in the yard is doing great. The unhappy tree has been getting regular water for the past 2 months, but has not regained its leaves.

Does anyone have any ideas? How can I tell if this tree is clinging to life and save it if it is?

 

[TNTreeHugger]

Why is it there?
Do you want shade? Food? Shelter for wildlife?
Seems to me, especially if you don't know what it is, and it's an eyesore, I'd get rid of it and either replant with something you want to serve a specific purpose (since the yard looks to be very small and space limited), or put something like bird feeder in it's place.
Just my opinion...