Diagnosing leaf discoloration on parrotia

Question: We've noticed some discoloration on some of the leaves of a parrotia persica that we planted about a year ago. The tree looks fairly healthy overall, but I first noticed discolored spots/edges on some of the leaves after the first time I watered the tree a few weeks after the rain stopped for the season. The discoloration on the edges is dried and crispy in some spots. I've only watered the tree a second time this season, and I can't tell whether the spots are the same or worse. The tree is planted about 15 feet northwest of the house, and the spots seem to be mainly occurring on the leaves on the east side of the tree, which is more shaded. 

Any idea what might be causing this? I've attached pictures below.

responder: Jacki D., Master Gardener Diagnostician Volunteer (Washington, Multnomah and Clackamas Counties) Oregon State University Extension Service Volunteer Metro Master Gardeners (http://metromastergardeners.org/) Replied June 12, 2023, 12:31 PM EDT
response: A photo of a leaf underside may help diagnosis. Pick one and work with your camera in good lighting and closeup settings if needed. Do top side also. Capture the texture—are there little fruiting spores? Additionally, a stressed tree is a disease and insect susceptible tree. This is a good chance to review basic planting and care. Pull back the weeds and freshly mulch the root zone. Describe how the tree was planted: hole size, depth, amendments used, if any, how root ball was treated, any wrapping materials dealt with. See EC 1438.

responder: The Question Asker Replied June 12, 2023, 3:51 PM EDT
response: Thanks for your help, Jacki. I've attached some additional leaf images. The texture appears smooth to me -- just kind of burnt and dried. I don't see anything that looks like spores as far as I can tell, but I may be missing something. I don't know much about the other information on hole size, depth, root ball treatment, etc. The tree was planted by a professional landscaping company, but I didn't watch the process. I haven't added any amendments.AlissaOn Mon, Jun 12, 2023 at 9:31 AM Ask Extension <<personal data hidden>> wrote:

responder: Jacki D., Master Gardener Diagnostician Volunteer (Washington, Multnomah and Clackamas Counties) Oregon State University Extension Service Volunteer Metro Master Gardeners (http://metromastergardeners.org/) Replied June 14, 2023, 9:50 PM EDT
response: I’m concerned your tree might be planted too deeply, and that burlap or root cage might not have been removed. Landscapers often make these errors. Gently pull back soil & mulch around the trunk and share photos of the root flare. The link is a pretty big slideshow from Clemson that’s maybe overkill, but the photos are excellent. The reason I’m bringing this up is because a stressed tree more easily succumbs to leaf spot problems. After you reply, I’ll probably refer your question to another expert to help determine if the leaf problem is disease or drought response.

responder: The Question Asker Replied June 16, 2023, 12:53 AM EDT
response: Thanks, Jacki. I've attached pictures of the base of the trunk before and after pulling away the soil and mulch around the root flare. Thanks for your help!AlissaOn Wed, Jun 14, 2023 at 6:50 PM Ask Extension <<personal data hidden>> wrote:

responder: Jacki D., Master Gardener Diagnostician Volunteer (Washington, Multnomah and Clackamas Counties) Oregon State University Extension Service Volunteer Metro Master Gardeners (http://metromastergardeners.org/) Replied June 16, 2023, 10:30 AM EDT
response: The tree is planted too deep. I’m wondering if the roots were spread out, or if left in circling shape from when growing in a pot. Many potted trees are too deep even when purchased. Eventually, circling roots can “strangle” a tree, and buried roots struggle to get the oxygen needed. I think your leaf damage along the margins and tips is from drought. The tree now needs deep watering right to the rootball in addition to the surrounding soil. How much? Not soggy, but leave the hose on drip for awhile each week and dig into the soil a bit to check where the water is going. No weeds and organic (not bark) mulch over the root area will help hold soil moisture. The goal is to keep the tree healthy while the roots spread out into the surrounding soil. Roots follow moisture, and water doesn’t easily move between soil that’s different. This is why shaking off planting compost, spreading roots, and never amending the tree planting hole is part of current planting recommendations. (Planting tips) It’s a thought to dig and replant your tree this winter. You could prune circling roots if any and adjust the planting depth. As a volunteer, that’s a big step for me to recommend and I’m not sure it’s necessary. You could hire a certified arborist to make a recommendation. Also, though, I’ll refer this question thread to an OSU Extension Agent for review.  Parrotia persica is described in this OSU page. It’s a favorite tree of mine, and I hope yours grows well for many years.

responder: The Question Asker Replied June 22, 2023, 2:48 PM EDT
response: Thanks for all of your help, Jacki. I've started on some deep watering and will clear out a wider mulched area around the tree. Thanks, too, for forwarding the question thread to an OSU Extension Agent. I appreciate it. AlissaOn Fri, Jun 16, 2023 at 7:30 AM Ask Extension <<personal data hidden>> wrote:

responder: Jacki D., Master Gardener Diagnostician Volunteer (Washington, Multnomah and Clackamas Counties) Oregon State University Extension Service Volunteer Metro Master Gardeners (http://metromastergardeners.org/) Replied June 23, 2023, 12:59 AM EDT
response: You’re welcome. The agent let me know he had nothing to add.