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Oak Leaf Mountain Ash Diseases #812284

Asked September 26, 2022, 4:01 PM EDT

Hello,

I have an Oak Leaf Mountain Ash in a Fort Collins neighborhood that has exhibited chlorosis on one half of the tree for the past two years and this year is exhibiting browning and leaf curling with premature leaf drop at the tips of some branches.

Larimer County Colorado

Expert Response

Hi Steve,

Could you provide me with some photos of the tree? Both of the leaf damage and also the tree as a whole (base included). Thank you!

If it's easier, you can email me directly: <personal data hidden>
Alison O'Connor, PhD Replied September 27, 2022, 5:14 PM EDT
Thank you for your reply! 

I will send a couple of emails with photos of the tree. You will also notice the increased lean. I'm wondering if restaking the tree is still a viable option given its size...

Thank you, 

Steve Singleton 


From: askextension=<personal data hidden> <askextension=<personal data hidden>> on behalf of Ask Extension <<personal data hidden>>
Sent: Tuesday, September 27, 2022 3:14:30 PM
To: Steve Singleton <<personal data hidden>>
Subject: Re: Oak Leaf Mountain Ash Diseases (#0082214)
 
The Question Asker Replied September 28, 2022, 5:56 PM EDT
Hi Steve,

Perhaps the photos aren't showing the lean as much as you'd like. That's something that can be addressed with an arborist, but truthfully, correcting a lean would be difficult, if not impossible. I suspect the tree is stable, but an arborist can assess it for structural integrity.

The chlorosis could be for several reasons, and generally it's linked to some root issue. One of the things we see with trees that generally don't get chlorosis, is the cultural conditions. It could be getting too much water or the area around the tree may not have the best drainage. A root may be affected by construction, girdling, etc. Because the entire tree isn't affected, it's something specific with the roots linked to that portion of the tree. 

I don't know if I would worry about it at this point in the season. We're nearing leaf drop. One thing to consider would be to remove the rocks as mulch and replace them with wood mulch, keeping it a few inches away from the trunk. Water in winter, about once per month, and avoid stressing the tree. 
Alison O'Connor, PhD Replied September 29, 2022, 5:22 PM EDT
Thank you for your insight!


From: askextension=<personal data hidden> <askextension=<personal data hidden>> on behalf of Ask Extension <<personal data hidden>>
Sent: Thursday, September 29, 2022 3:22:37 PM
To: Steve Singleton <<personal data hidden>>
Subject: Re: Oak Leaf Mountain Ash Diseases (#0082214)
 
The Question Asker Replied October 02, 2022, 1:27 PM EDT

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