Will these spots kill my tree?

Usually no, as Osage orange is a very tough tree. It is mostly an aesthetic issue unless the infection is severe enough to cause total defoliation.

Should I use a fungicide?

Fungicides are rarely needed for mature trees. Focus on cleaning up fallen leaves and improving airflow instead.

Osage orange: spots, causes and fixes

Check these first

Inspect the underside of the leaves for signs of fuzzy fungal growth.
Check if the tree is crowded by other plants that block airflow.
Look at the weather patterns over the last two weeks for excess rain.

Likely causes

Fungal Leaf Spot
Most likely
How to tell: You will see dark or brown spots appearing on the leaves during periods of high humidity or frequent rain. The spots may grow larger or cause the leaf to yellow prematurely.
What to do: Remove and destroy any fallen leaves from around the base of the tree to stop spores from spreading. Prune away crowded branches to improve air circulation through the canopy. Avoid overhead watering that wets the leaves.
Bacterial Blight
Possible
How to tell: This often looks like angular, water soaked spots that eventually turn dark brown or black. It spreads quickly during cool, wet spring weather.
What to do: Prune out infected twigs and branches during dry weather to prevent further spread. Sterilize your pruning tools with rubbing alcohol between every cut. Ensure the tree is planted in a spot with full sun to help foliage dry out quickly.

Leaf spots on other plants

Find out what's wrong with your osage orange

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.

When to worry

It is normal to see a few spots after a very rainy season, but you should worry if the entire canopy is defoliating. If the spots are spreading rapidly and causing significant leaf drop, take action.

Stopping it coming back

Keep the area under the tree clear of debris and ensure it gets full sun to keep the leaves dry.

Osage orange: spots? Check yours with a photo

Every plant is a little different. Take a photo of your osage orange 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.

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

Questions people ask

Will these spots kill my tree?: Usually no, as Osage orange is a very tough tree. It is mostly an aesthetic issue unless the infection is severe enough to cause total defoliation.
Should I use a fungicide?: Fungicides are rarely needed for mature trees. Focus on cleaning up fallen leaves and improving airflow instead.

Guides to these causes

Leaf Spot

Why are there dark spots on my Osage orange leaves?