Hawthorne tree distress

Question: My hawthorne was slow to leaf out this spring and some branches never did get leaves.  Now many leaf tips are brown.  What is this and what do I do?

responder: Alison O'Connor, PhD  Replied July 01, 2024, 1:59 PM EDT
response: Hi Paula,  The tree is very chlorotic (yellow) and the leaves are essentially "sunburned" because there is no chlorophyll pigment (green color) in the leaves to protect the leaves.   But now the question is: Why is the hawthorn so chlorotic? This is a tree that does very well in our soils and environment. Tell me more about the tree and how it's cared for - does it get fall/winter water? Was it planted at the correct depth? It's in the lawn, which I assume receives regular irrigation - how often (days/week) and how long (number of minutes) do you irrigate each week?  Thanks!

responder: The Question Asker Replied July 01, 2024, 10:12 PM EDT
response: Thanks for the answer.  The tree was planted in 2003 and had been happy until this year.  The first few years I watered roughly monthly throughout the winter, but haven't for several years.  However I have changed my summer watering as a result of a Fort Collins Loveland Water District sprinker audit last summer.  I got new nozzles and changed the run times.  The tree is centered on a slightly sloping grass area and gets water from two different zones, the top half of the yard and the bottom half.  Each zone runs 20 minutes, twice a week.  I believe previously  I was watering 3 days a week for the same amount of time.  The grass under the tree is green and happy, but that outside of the tree's shade doesn't seem to be getting enough water.  Should my first step be to increase the watering?   Paula   From: ask=<personal data hidden> <ask=<personal data hidden>> on behalf of Ask Extension <<personal data hidden>> Sent: Monday, July 1, 2024 11:59 AM To: Paula Galloway <<personal data hidden>> Subject: Re: Hawthorne tree distress (#0145248)

responder: Alison O'Connor, PhD  Replied July 01, 2024, 10:21 PM EDT
response: Hi Paula,  No, watering more may not be the solution, because chlorosis can be linked to overwatering, which isn't likely happening (unless there's a leak). It can also be caused by compacted soils, salts (unlikely on treated water), or cold soils (common in early spring).  Is the tree suckering at the base? Does it have a root flare? Any damage to the tree or the trunk?

responder: The Question Asker Replied July 03, 2024, 11:39 AM EDT
response: There isn't any suckering at the base.  I don't see much flare. There hasn't been any damage to the tree.  On Mon, Jul 1, 2024, 8:21 PM Ask Extension <<personal data hidden>> wrote:

responder: Alison O'Connor, PhD  Replied July 03, 2024, 12:14 PM EDT
response: Thanks, Paula.  It might be planted a little deep. One thing to consider would be to remove the grass below the tree - as far out as you wish - and then add some wood mulch, keeping it a few inches away from the base.   This will eliminate any maintenance of the grass around the trunk (which can be damaging). Equipment can "ding" the trunk and cause significant injury.   Let's see how the tree does over the next couple of months - we do have a Tree Team, comprised of volunteers, that could come out and assess to see if there's additional recommendations. The cost for the visit is $25. If you're interested in this, please email me directly and include your full contact information (including phone number, Zip code, and address).  My email is: <personal data hidden>