Why Are There Yellow Leaves on Trees in Summer?

Why Are There Yellow Leaves on Trees in Summer?

Rich, green leaves are a staple of summer. They’re crisp, bright and a pleasant addition to every landscape. Plus, we love their shady canopy on sunny days.

So if you spot yellowing leaves on your trees, you want them to return to their green glory. An Ontario-based reader recently had a similar goal. She asked us why her river birch leaves were turning yellow and falling off – and how she could fix it.

There are many reasons why you too could see these symptoms. Run down the checklist below to help diagnose your tree.

Test 1: Test for dry soil

If trees aren’t hydrated, the leaves can turn yellow as they try to conserve water.

Test your tree’s moisture by sticking a screwdriver into the soil. If it’s hard to push in, chances are the tree is thirsty and could use a deep watering.

Test 2: Check soil moisture

If the screwdriver test proves there’s moisture deep into the roots, water less.

Your reflex might be to water at the sight of suffering leaves, but overwatering can also lead to yellowing and leaf drop.

Test 3: Inspect and treat

Yellowing leaves and premature leaf drop may point to a leaf disease or summer pest infestation. Consider a free tree inspection to identify the pest or disease and the best treatment.

If an infestation is ruled out, the checkup may reveal a deficiency called chlorosis, which strips leaves of the chlorophyll needed to keep them green.

Begin by performing a soil test and adding any necessary soil amendments. Fertilizer also replenishes lacking nutrients, which in turn helps your tree. Remember, these actions need to happen on a regular basis to have a lasting impact.

Why, specifically, is my birch or river birch getting yellow leaves in summer?

If you, too, are seeing yellow leaves on your birch tree, there could be a couple reasons why.

Run through this checklist just for birch trees to find out what the problem is:

  • Are there spots on those yellow birch leaves? If so, the problem is likely a leaf disease.
  • Do you see something sticky on the bottom of the leaves? If so, it’s probably an insect.
  • How much are you watering? As their name implies, river birches love to drink water. In the summer, when the water is limited, they’ll drop leaves if they get thirsty enough. To remedy, deeply water your birch tree each week, and add mulch to conserve moisture.
  • How hot is it? If it gets too hot for too long, these trees drop leaves to conserve energy. This happens most often to newly planted trees. They toughen up a bit as they mature because their root system becomes better established.
  • Didn’t see any of the above? Check the soil to see if there’s enough iron (or if the soil has too much pH). Remedy the problem with soil amendments or treatments.

Have a question about the appearance of your tree? Comment below for help from our Davey scientists!

  • The Tree Doctor July 14, 2017 >Hi Renee. This sounds like the leaves could be falling due to the extremely high temperatures your area has had recently. Watering excessively can actually be compounding the issue. Take a look at our blog post about watering trees during a drought for some tips, blog.davey.com/2016/08/how-often-to-water-trees-during-a-drought/. Here if you have any other questions, Renee.
  • The Tree Doctor July 14, 2017 >Hi Kim! We would recommend pruning your crabapple in late fall, when it is dormant season. We have passed along your request for fertilization to your local office, so they should be reaching out soon to set up an appointment. Or if you’d prefer, you can contact them at 303.515.7492 or davey.com/local-offices/east-denver-tree-service/. Here if you have any other questions, Kim.
  • Renee Braun July 14, 2017 >My i think its a (fruitless pear) tree is RAINing LOTS of leaves today. we live in Oakley Ca. It has been dry and very warm. But the sprinklers have been on daily so it is getting water. The soil is moist to wet on one side of the tree but near dry on the other. There was potted plants blocking the spray. My husband thought it was causing you much water too fall on tree. I think not enough. What do we do to help the tree?
  • Kim Prager July 13, 2017 >I need to get my oak fertilized and the spruce to the right of crabapple and left of water feature. Also what is the earliest I can cut my crabapple? January? Kim prager
  • The Tree Doctor August 29, 2016 >Hi again, Amelia! Ok, got it. Thanks for sharing! You've got a solid plan. Start with those steps, and see if your tree begins to improve. If not, have your arborist inspect your tree for pests when he's fertilizing in the fall. Wishing you and your trees all the best, Amelia. Always here if you need any further help.
  • Amelia Racca August 26, 2016 >Thanks for the info. Yes, my tree faces South. I seldom water the tree and never spray the leaves. The North side of the tree is just now starting to show fall colors. I will check the soil for dryness and will fertilize this fall. Any other advice? Thanks again for the quick response.
  • The Tree Doctor August 26, 2016 >Hi there, Amelia. Oh no - sorry to hear your pruned Japanese maple is struggling. Luckily, you're keeping a close eye on it! Our Davey scientists are curious... What direction is your tree facing? If your tree is facing South, this could be leaf scorch, due to the heat and sun. Also, are you watering your tree during the middle of the day? This could actually magnify the sun on the leaves and brown them. Hope this helps, Amelia. If you'd live to talk more, email us directly at blog@davey.com. Take care.
  • Amelia Racca August 26, 2016 >My Japanese maple's leaves are turning brown at a fast rate starting on one side of the tree. This is new....due to lack of water? Had the tree trimmed by you folks in May 2016. Needs fertilizer? Gropher problem? Thanks for your help.
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