Tree problems · Disease
Sooty mold: signs and what to do
Sooty mold is a tree disease, often seen on crape myrtle, maples, southern magnolia. Look for: a black, soot-like coating on the upper side of leaves, twigs or fruit.
General information, not a diagnosis. A certified arborist or your county extension office can confirm.
- Disease
- Crape myrtle
- Maples
- Southern magnolia
- Tulip poplar
- Linden
- Dogwood
Signs to look for
Tick what you see. More ticks make it more likely, but only an on-site look can confirm.
0 of 6 signs ticked. Ticks stay in this browser only.
Season
It shows up during the growing season when sap-feeding insects are active and honeydew builds up. The black coating often grows thicker in warm, humid weather.
How it spreads
Sooty mold fungi live on honeydew, the sugary waste of insects such as aphids and scale. It is not an infection of the leaf itself. The mold appears wherever enough honeydew falls, and it does not move from tree to tree on its own.
Where it is found
Sooty mold can show up anywhere in the United States where trees host sap-feeding insects. It is a common landscape problem rather than a regulated pest.
Official sources
What to do
- 1
Look closely under leaves and on twigs for aphids, scale or other sap-feeding insects.
- 2
Take photos and bring a sample to your county extension office to identify the insect.
- 3
Treat the insect problem, not the black coating. Extension sources say most sooty mold is controlled by controlling the insects.
- 4
Ask your extension office before using any pesticide on a home tree. Right product and timing matter.
- 5
Rinsing leaves with a strong stream of water can wash some of the coating off.
- 6
Keep the tree watered and healthy so it can cope with the insects.
Safety first: do not climb, do not cut near power lines and do not use a chainsaw on storm-loaded wood. Call the utility for downed lines and 911 if anyone is in danger.
Prevention
Watch trees for insects early in the season, since the mold only grows when honeydew is present. Healthy, well-watered trees cope better. Choose a mix of tree species when you plant. Ask a certified arborist about options that fit your tree, and avoid spraying more than needed, because broad sprays can also harm helpful insects.
When to call a pro
Call a certified arborist if a valuable tree has heavy honeydew and black coating year after year, if branches are dying, or if you are not sure what insect is causing it. Work on tall trees near power lines and buildings should be done by a trained, insured crew.
Not sure who to call? Read how to hire a tree service or check is my tree dangerous?
Trees it affects
Usually seen on: Crape myrtle, Maples, Southern magnolia, Tulip poplar, Linden, Dogwood, Pecan, Live oak.
- Crape Myrtle
- Red Maple
- Silver Maple
- Southern Magnolia
- Tulip Poplar
- American Linden
- Flowering Dogwood
- Pecan
- Southern Live Oak
See all species in our tree library, or pick a tougher tree with the tree picker.
For tree companies
How to explain sooty mold to a customer
Explain that the black coating is a sign, and the real question is which insect is making honeydew. Be honest that sooty mold is mostly a cosmetic and sticky-mess problem. Do not sell removal for it. Offer to identify the insect and give a clear, written treatment option.
Send this page to the customer after your visit so they can read the signs in plain words. See also selling plant health care and the job photo checklist.
Questions
What is sooty mold?
It is a black fungus that grows on honeydew, the sticky waste left by insects such as aphids and scale. It sits on the surface of the leaf like a layer of soot.
Does sooty mold kill trees?
Usually not by itself. A thick coating can block some light from the leaf. The bigger concern is the large number of sap-feeding insects that made the honeydew.
How do I get rid of it?
Control the insects that make honeydew. Once they are gone, the mold slowly weathers away. Rain or a water rinse can help wash it off.
Why is my tree dripping sticky stuff?
That is honeydew from insects feeding on the tree above. It can land on cars, decks and patios. Washing it off soon is easier than letting it dry.
Should I spray fungicide?
Fungicide usually does not fix the cause. Extension sources point to dealing with the insects. Ask your extension office what fits your tree.
Why are there ants on my tree?
Ants feed on honeydew. They often protect the insects that make it, so lots of ants can be a clue that aphids or scale are present.
Can Lirevon diagnose sooty mold on my tree?
No. Lirevon is a remote marketing team for tree service companies and does not do tree work. This page is general information, not a diagnosis. A certified arborist or your county extension office can confirm what is wrong with your tree.
How do I find a good local pro for this?
Search Google Maps for certified arborists or tree services near you, read their reviews and ask for proof of insurance. Get two or three written quotes. Our guide on how to hire a tree service lists the questions to ask.
Related tree problems
- Aphids (Insect)
- Cankers (Disease)
- Girdling Roots (Other damage)
- Herbicide damage (Other damage)
- Scale insects (Insect)
- Sunscald (Other damage)