Autumn maple, please with brown edges

Question: I have two relatively new autumn maple trees in our backyard in Highland Ranch, Colorado. Moisture meter I bought from Home Depot says they have plenty of water. I have fertilized them in the past three months. When has been in the ground two years, the second one has been in the ground one year. They are both developing leaves with brown/yellow edges. I'm trying to figure out what the solution is, if there is one. It is the beginning of September. Thank you for your support.

responder: Kind Regards,  Replied September 04, 2024, 1:00 AM EDT
response: John,  Thank you for reaching out to us. We appreciate the clarity of the photos you provided, but unfortunately, it's tough to tell the cause of your leaf scorch just by looking at the leaves themselves. There are many factors that can cause such damage, including over watering, under watering, over fertilization, heat stress, etc.   While your moisture meter may be indicating the soil is adequately moist, the depth of the extent of that moisture makes a big difference in determining if you tree is getting enough water, or if it's only adequate to ensure happy turfgrass roots. It's also been pretty hot lately, so if the tree roots aren't getting enough water, the brown margins and yellowing of the leaves may indicate the trees struggled to cope with the high temperatures.   Then again, too much water can result in the same signs of stress caused by inadequate oxygen availability in the soil.   Another possibility could be that the type and quantity of the fertilizer you used could have caused a build up of excess salts, which can also burn roots.   Basically, we'll need more photos of the trees (both close-up and wide angle), and more information on their location on your lot (i.e. what direction they're facing), what lies beneath them (e.g. grass, rock mulch, wood mulch, etc), how you water them, how often you water them, how much you water them during each irrigation session, what sort & quantity of fertilizer you applied, when the leaf scorch was first noticed, and any other details you can think of. This will be very helpful to us in determining the cause of the damage. We can, however, confidently say that the signs of stress your maple leaves are showing are not due to the onset of a change in seasons.  Please do send the additional information when you're able to. We look forward to being of further assistance to you, both on this matter and any other gardening issues you encounter.  If you'd like to read more about leaf scorch, please go to CSU's fact sheet on the subject at <https://extension.colostate.edu/topic-areas/yard-garden/leaf-scorch-2-911/>

responder: The Question Asker Replied September 04, 2024, 5:22 PM EDT
response: Download full resolution imagesAvailable until Oct 4, 2024Thank you for getting back to me so quickly. I have included some additional information below.BTW, you might have to click on a link to download these videos and pictures because they take a lot of space. Hope this works.First, the yard is facing nearly south in the back. It does catch a lot of sun, and including a lot of reflected sun from the house.  The tree by the fence with plant two years ago and has been healthy since the beginning. The tree that is located away from the fence by the house was planted early last summer and has been healthy. Both trees showed a little yellowing of the edges of the leaves earlier this summer, but that went away. Now they're both showing it, of course we've had some very hot weather too.I have not been watering more or less, and in fact, we had the centennial water people come by and make a recommendation how much we need to water the yard and keep within their budget, and that's what we do. Both trees are in the watering area. By the split rail fence, there is a French drain because that swale area used to get too wet due to the sump pump action from my neighbors. So it shouldn't be an issue now.I've enclosed a bunch of new pictures, and a video, I hope it helps. I also showed a picture of the fertilizer that I've put sparingly on the tree by the house, not the one by the back fence.Click to DownloadIMG_2977.MOV102.5 MBjohnOn Sep 3, 2024, at 11:00 PM, Ask Extension wrote:

responder: Kind Regards,  Replied September 04, 2024, 6:32 PM EDT
response: John, Thank you for sending these pictures.  The first thing we noticed is that your tree was likely planted too deep.  Properly planted trees show the flare at the bottom of the tree, the trunk should not look like a telephone pole.  This link may be helpful: https://csfs.colostate.edu/colorado-trees/selecting-planting-and-caring-for-trees/From our research, when maple tree leaves turn brown and yellow, there can be many causes:  overwatering, injury to the tree's trunk or root, improper planting, excessive fertilization, herbicides, drought or other reasons.  You might dig down a bit to see how wet the soil is.  The grass looks very green in that area, and it could be caused by overwatering. Since we are in September, you will be watering less this month.regards,Extension Master Gardeners of Douglas County, Colorado<personal data hidden><personal data hidden>Your garden can help feed the community. Learn more now at growandgivecolorado.orgOn Wed, Sep 4, 2024 at 3:22 PM Ask Extension <<personal data hidden>> wrote: