Skip to content
Pocket Botanist
Get the app

Mulberry · Morus

Why does my mulberry fruit look like popcorn?

If your mulberry fruit is swelling into strange, white, puffy shapes, it is likely suffering from a fungal issue called popcorn disease. This fungus targets the developing fruit and ruins the harvest.

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. Examine the fruit for white, puffy distortions.
  2. Check if the weather has been unusually wet lately.
  3. Look at the density of the tree branches.

Likely causes

  1. Popcorn disease fungus

    Most likely

    How to tell: The fruit becomes enlarged, white, and distorted, resembling a piece of popcorn. This usually happens during wet, humid spring weather.

    What to do: Remove and destroy all infected fruit immediately to stop the spread of spores. Do not compost the infected fruit, as the fungus can survive in the pile.

  2. Poor air circulation

    Possible

    How to tell: The tree canopy is very dense, trapping moisture and humidity around the developing fruit. This creates the perfect environment for fungal growth.

    What to do: Prune the tree during the winter to open up the center of the canopy. This allows sunlight and air to reach the inner branches, keeping the fruit dry.

Leaf spots on other plants

Find out what's wrong with your mulberry

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

This is a serious issue for your fruit harvest, though it rarely kills the tree itself. If you see it, act quickly to prevent the fungus from spreading to the rest of the crop.

Stopping it coming back

Clean up all fallen leaves and fruit from beneath the tree in the autumn. Keeping the area under the tree clear reduces the amount of fungus that can infect the tree next spring.

Mulberry: spots? Check yours with a photo

Every plant is a little different. Take a photo of your mulberry 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

Is the fruit safe to eat if it has popcorn disease?
No, you should not eat fruit affected by this fungus. It is best to discard it entirely.
Will this disease kill my tree?
No, it is a fruit disease and generally does not harm the health of the tree itself. It just ruins the current season's harvest.

More problems with Mulberry

Back to the Mulberry 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.