Hedge maple leaves turning yellow then brown - Ask Extension
Hi there. I live in NE Portland and about 3 weeks ago the leaves on my hedge maple starting turning yellow and brown (mostly from the bottom of the tr...
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Hedge maple leaves turning yellow then brown #877377
Asked July 15, 2024, 6:34 PM EDT
Hi there. I live in NE Portland and about 3 weeks ago the leaves on my hedge maple starting turning yellow and brown (mostly from the bottom of the tree moving up) and it's now looking like I may ultimately lose them all. The tree is in the parking strip. I think I've watered it adequately, without overwatering. Any thoughts on cause and what I can do? Thank you very much.
Photos attached
Multnomah County Oregon
Expert Response
Hi Matt- Thanks for your question about your maple tree. The symptoms look like either drought/heat stress or a fungal disease called Anthracnose. Both have similar symptoms of the tan tissue along the leaf veins that I am seeing in your picture.
There is nothing to do now if it is Anthracnose, but you can spray the tree next spring with Bonide Fung-onil Multi-purpose Fungicide at 2.25 teaspoons/gal water. Follow the directions exactly!
If the cause is heat stress, which I think is more likely as maples are prone to this problem, there are a couple of things you can do. First, water more! The bark dust around the base of your tree can be hydrophobic, meaning that the water runs off rather than sinking into the ground. Stick your finger deep in the ground after watering to see if the water is really reaching the roots.
Second, see if you can give your tree some shade on our hottest days by making some kind of shade barrier to the southwest to give it a shadow in the afternoon.
https://www.heartwoodtree.com/are-your-trees-suffering-from-summer-heat-stress/
Keep the fallen leaves raked up in case it is the fungus, and keep an eye on possible new growth with some extra water.
Good luck,
There is nothing to do now if it is Anthracnose, but you can spray the tree next spring with Bonide Fung-onil Multi-purpose Fungicide at 2.25 teaspoons/gal water. Follow the directions exactly!
If the cause is heat stress, which I think is more likely as maples are prone to this problem, there are a couple of things you can do. First, water more! The bark dust around the base of your tree can be hydrophobic, meaning that the water runs off rather than sinking into the ground. Stick your finger deep in the ground after watering to see if the water is really reaching the roots.
Second, see if you can give your tree some shade on our hottest days by making some kind of shade barrier to the southwest to give it a shadow in the afternoon.
https://www.heartwoodtree.com/are-your-trees-suffering-from-summer-heat-stress/
Keep the fallen leaves raked up in case it is the fungus, and keep an eye on possible new growth with some extra water.
Good luck,
