Skip to content
Pocket Botanist
Get the app

Eastern Cottonwood · Populus deltoides

Why does my Eastern Cottonwood have spots on its leaves?

Leaf spots on an Eastern Cottonwood are often caused by fungal infections that thrive in wet conditions. These spots can look like small brown or black dots scattered across the foliage. Check your tree after a period of heavy rain or high humidity.

Not sure it's this? Check a photo of your plant for free

spots on a plant
Photo: Scot Nelson, CC0

Check these first

  1. Look for spots on the lower branches first.
  2. Check if the spots have yellow halos.
  3. Examine the ground for fallen, infected leaves.

Likely causes

  1. Septoria leaf spot

    Most likely

    How to tell: Small, dark brown spots with lighter centers appear on the leaves. In severe cases, the leaves may turn yellow and fall off prematurely.

    What to do: Rake up and dispose of all fallen leaves beneath the tree to prevent spores from spreading. Improve air circulation by pruning away crowded or crossing branches.

  2. Marssonina leaf spot

    Possible

    How to tell: Dark brown or black spots appear on the leaves, often accompanied by yellowing. This fungus is most active during cool, wet springs.

    What to do: Apply a copper-based fungicide in early spring if you have a history of this infection. Ensure the tree is not being hit by overhead sprinklers that keep the leaves wet.

Leaf spots on other plants

Find out what's wrong with your eastern cottonwood

The list above covers the usual causes. Pocket Botanist looks at a photo of your actual plant and tells you the likely cause, how serious it is, and what to try first. Identification and a health check are free.

Download on the App StoreGet it on Google Play

When to worry

It is serious if the tree loses most of its leaves by mid-summer. Minor spotting late in the season is usually harmless.

Stopping it coming back

Water at the base of the tree rather than wetting the leaves. Keep the area under the canopy clean of debris to stop fungal spores from overwintering.

Eastern Cottonwood: spots? Check yours with a photo

Every plant is a little different. Take a photo of your eastern cottonwood and Pocket Botanist tells you which cause is most likely, how serious it is, and what to try first. A few checks a day are free. Save the plant and you get care reminders timed for it.

Download on the App StoreGet it on Google Play

Get the app · Or check it from a photo now, free

Questions people ask

Will leaf spot kill my tree?
It rarely kills a mature tree, but it can weaken it over several years. Focus on keeping the tree vigorous with proper watering.
Can I compost the spotted leaves?
No, do not compost them. The fungal spores can survive and re-infect your tree next year.

Guides to these causes

More problems with Eastern Cottonwood

Back to the Eastern Cottonwood guide

This article was generated with AI on from the plant’s care profile and is general information, not horticultural advice. Read about how we build these guides.