Quick answer: Sooty mold is a black film that grows on insect honeydew, and it wipes off the leaf. Anthracnose is a fungal disease that makes dark, sunken spots in leaves, flowers, or fruit, and it does not wipe off. Do a wet-cloth rub test. If the black comes off, treat the insects. If it stays, manage the disease.
Your mango leaves have black on them. Is it sooty mold or anthracnose? From across the yard, the two look alike. Up close, they are very different problems.
Sooty mold is a film that sits on top of the leaf. Anthracnose is a disease that lives inside the leaf. The fix is different for each one, so it pays to know which you have before you spray anything.
A note on sources: this guide relies on US and international university extension publications, linked at the bottom. Spray products, timing, and rules change by state, so always check the product label and your local extension office before you treat your tree.
Do the Wipe Test First (30 Seconds)
This one test sorts most cases. You only need a damp paper towel or soft cloth.
- Wet the cloth with plain water.
- Rub a black area on a leaf with light pressure.
- Look at the leaf and the cloth. If the black comes off and a clean green leaf shows underneath, you most likely have sooty mold. Queensland’s agriculture department describes it this way: the black covering rubs away, and the tissue under it is undamaged.
- If the black stays, it is part of the leaf. Look closely for the spots described in the anthracnose section below.
The wipe test: sooty mold rubs off and leaves clean green tissue behind
Sooty Mold vs. Anthracnose on Mango: Side-by-Side
| Feature | Sooty mold | Anthracnose |
|---|---|---|
| What it is | Fungi that grow on the surface of the plant | A fungal disease that infects the plant (Colletotrichum gloeosporioides) |
| What it feeds on | Sticky honeydew left by sap-feeding insects | Living plant tissue |
| What it looks like | A black, soot-like film, often over large areas | Small black or brown spots that grow, merge, and may crack or sink |
| Wipe test | Wipes off | Does not wipe off |
| Leaves feel | Often sticky (honeydew) | Not sticky |
| Where it shows up | Leaves, twigs, flower stalks, fruit | Leaves, flowers, twigs, and fruit |
| What helps it | Honeydew from scale, mealybugs, aphids, whiteflies, and similar insects; ants that protect them | Warm, wet, humid weather; rain or irrigation splashing spores |
| Harm to the tree | Mostly cosmetic. A heavy coat blocks light and can cause leaf drop | Can kill flowers, cut fruit set, and rot fruit |
| Fix first | The insects making honeydew | Sanitation, airflow, and protecting new growth and flowers |
What Is Sooty Mold on a Mango Tree?
What it looks like
Sooty mold looks like soot spread over the leaves. It is usually dark and thread-like, and it can cover leaves, twigs, and even fruit. The name comes from this sooty look.
What causes it
Sooty mold does not attack the plant. It grows on honeydew, a sweet, sticky liquid that sap-feeding insects pass while they eat. UC IPM explains that insects cannot use all the nutrients in the sap, so they release the extra as honeydew, and the fungus grows wherever it lands.
On mango, the University of Florida Extension names soft scales, mealybugs, aphids, whiteflies, and treehoppers as sources of honeydew. Ants make it worse. They feed on honeydew and protect the insects that make it from natural enemies.
Is it harmful?
Sooty mold does not infect the leaf. But a thick coat can block sunlight. UC IPM says that can slow growth and cause coated leaves to age early and drop. Light sooty mold is mostly a sign that insects are present.
Want the full treatment plan? See our guide to sooty mold on mango trees.
What Is Anthracnose on a Mango Tree?
Anthracnose is caused by the fungus Colletotrichum gloeosporioides. University of Florida Extension calls it one of the most serious mango diseases in Florida, especially where it rains during flowering and fruiting. The University of Hawaiʻi calls it the most important and destructive mango disease worldwide.
On leaves
Spots start small, angular, and brown to black. They can grow into large dead patches. In dry weather, the dead tissue may drop out and leave holes. Spots often form near the leaf edges, and young leaves on new growth are the most open to infection. Young spots may have a yellow halo.
On flowers and twigs
On flower clusters, the first sign is tiny black or dark-brown specks. They can spread, merge, and kill the flowers before fruit forms. Twigs can get black, spreading lesions and die back from the tip.
On fruit
Fruit gets dark, sunken spots that can spread and rot the flesh. Some fruit shows long “tear stain” marks and cracks. Many infections stay hidden on green fruit and show up only as the mango ripens. So a mango can look clean at harvest and still develop spots later. In wet weather, you may see pinkish-orange spore masses on the lesions.
How it spreads
Rain and irrigation splash spores from one spot to another. The fungus survives between seasons on infected twig tips and older leaves, according to the University of Hawaiʻi.
Anthracnose spots are part of the leaf or fruit. They do not wipe off.
Can a Mango Tree Have Both?
Yes. The two problems have different causes, so one tree can show both at the same time. Sooty mold follows insects and honeydew. Anthracnose follows wet, humid weather.
Here is a simple way to check. Wipe the black film off a leaf first. Then look closely at the clean leaf. Any dark spots left behind are not sooty mold.
Other Problems That Can Look Similar
Bacterial black spot, mango scab, and thrips damage can also leave dark marks on leaves. If the wipe test fails and the spots do not match the anthracnose description, read our guide to why mango tree leaves turn black. It covers seven possible causes.
What To Do Next
If it is sooty mold
- Find the insects. Check the underside of leaves and the young shoots. Our guide to scale insects on mango trees shows what to look for.
- Control ants. UC IPM notes that ants protect honeydew-making insects. Keeping ants out of the tree lets natural enemies do their job.
- Clean what you can reach. A strong stream of water, or soap and water, washes sooty mold off small trees. See how to remove sooty mold from mango leaves safely.
- Do not expect a fungicide to clear the black. University of Florida Extension notes that a general-purpose fungicide may kill the fungus but does not remove the black color.
If it is anthracnose
- Clean up. The University of Hawaiʻi advises yearly pruning and removing fallen plant debris, because the fungus survives on dead and infected plant parts. For safe cuts, see our pruning guide for mango.
- Open the canopy and give trees room. Wider spacing helps leaves dry faster and slows epidemics, according to the University of Hawaiʻi.
- Keep water off the leaves when you can. Splashing water moves the spores.
- Protect flowers and new growth. University of Florida Extension says copper fungicide, used as the label directs, controls anthracnose, and advises starting when flowers begin to form. The University of Hawaiʻi says timing is critical and sprays begin when flower clusters first appear and continue until the fruit is about 1½ to 2 inches long.
Before you spray anything: read the label and make sure it lists mango or fruit trees and your use site, such as a home landscape. Follow the label for rate, timing, protective gear, and bee safety. Product registrations differ by state, so check with your local extension office. I am not giving mixing rates because they depend on the product label. University of Florida Extension also notes that most pest and disease problems on home-landscape mangoes are not intense, so ask your local office whether spraying is worth it for your tree.
If you have both
Work on both. Start with whichever one threatens flowers and fruit, which is usually anthracnose, and handle the insects at the same time.
What About the Mangoes?
Sooty mold on fruit: UC IPM says fruit covered with sooty mold is still edible. Wash it off with mild soap and warm water.
Anthracnose on fruit: This one is different. Spots can go deep into the flesh, and the University of Hawaiʻi notes that lesions can spread and rot the fruit. Food-safety writers often advise cutting away small, shallow spots and throwing out fruit that is soft, watery, or smells off. When in doubt, throw it out.
Common Mistakes
- Judging by color alone. Both problems look black. The wipe test takes 30 seconds.
- Spraying fungicide on sooty mold. It does not remove the black film, and it does not stop the insects that cause it.
- Ignoring ants. Ants keep honeydew-making insects safe, so the problem returns.
- Waiting until anthracnose spots show up. Timing is critical. Sprays work best when flowers and new growth are protected early.
- Leaving fallen leaves and fruit under the tree. They carry the fungus into the next season.
- Using a product that is not labeled for mango. The label is the law. Do not guess.
When To Call Your Local Extension Office
- You cannot tell which problem you have after the wipe test
- Spots keep spreading to flowers or fruit
- Your tree gets heavy leaf spots or dieback every year
- You want to spray and are unsure what is allowed in your state
Send close-up photos of the top and underside of a leaf, a whole branch, and the whole tree. A fresh sample is even better.
Frequently Asked Questions
1. How can I tell sooty mold from anthracnose on a mango leaf?
Rub the black area with a damp cloth. Sooty mold wipes off and leaves clean green tissue. Anthracnose spots are part of the leaf, so they stay put and often sink or crack.
2. Does sooty mold turn into anthracnose?
No. Sooty mold fungi live on honeydew sitting on the surface. The anthracnose fungus invades plant tissue. One does not change into the other, but a tree can have both.
3. Is sooty mold harmful to mango trees?
Sooty mold does not infect the tree. A heavy coat can block light and slow growth, and coated leaves may drop early. The bigger issue is the insects making the honeydew.
4. Is anthracnose worse than sooty mold?
For the crop, anthracnose can do more harm. It can kill flower clusters and rot fruit. Sooty mold is mostly cosmetic, but it signals an insect problem that needs attention.
5. Why are my mango leaves black and sticky?
Sticky leaves usually mean honeydew, and black on top of it usually means sooty mold. Look for scale, mealybugs, aphids, or whiteflies, and check for ants on the trunk.
6. Can I eat mangoes with sooty mold?
Yes. UC IPM says fruit with sooty mold is still edible. Wash it with mild soap and warm water.
7. Can I eat mangoes with anthracnose spots?
Be careful. Small, shallow spots can be cut away, but anthracnose can spread deep into the flesh. Throw out fruit that is soft, watery, or smells off.
8. Will fungicide get rid of sooty mold?
Not by itself. A fungicide may kill the fungus but does not remove the black color, according to the University of Florida Extension. Controlling the honeydew-making insects is the real fix.
9. What weather causes anthracnose on mango?
Warm, wet, humid weather. Rain or irrigation splash spreads the spores. It is most damaging when rain falls during flowering and fruit set.
10. When should I spray for anthracnose?
Extension sources point to protecting flowers and young fruit, starting when flowers begin to form. Exact products and timing depend on your state and the label, so confirm with your local extension office before you spray.
Sources and Further Reading
- UC IPM: Sooty Mold (Pest Notes, UC ANR Publication 74108) — what sooty mold is, honeydew insects, ants, damage, washing off, edible fruit
- University of Hawaiʻi CTAHR: Mango Anthracnose (PD-48) — symptoms on leaves, flowers, and fruit; disease cycle; sanitation and spray timing
- UF/IFAS Extension, St. Lucie County: Mango Tree Sooty Mold — insects behind mango sooty mold; fungicide does not remove the black color
- UF/IFAS Extension, St. Lucie County: Mango Anthracnose and its Management — anthracnose in Florida; copper fungicide timing
- UF/IFAS Extension, St. Lucie County: Common Problems of Mango in the Florida Home Landscape — home-landscape context and advice to contact local extension
- Queensland DPI: Mango Problem Solver — sooty mold black covering rubs away to undamaged tissue
- Eat or Toss: Dark, black slightly sunken spots on mango — food-safety guidance for anthracnose on fruit
This article is general information. It does not replace the product label or advice from your local extension office. Pesticide rules vary by state. Always read and follow the product label.
Rebecca Vittetoe
I’m Rebecca Vittetoe, a field agronomist working with farmers through Iowa State University Extension.
Most of my time is not spent in an office—it’s spent in the field. I work directly with farmers, crop scouts, and ag professionals to solve real problems they face every season. From pest pressure to nutrient issues, I focus on what is actually happening in the field—not just what is written in books.
Over the years, I’ve learned that good farming decisions come from a mix of research and real-world experience. That’s what I try to bring into everything I do.
At toagriculture.com, I share simple, practical insights from the field:
What I see in crops during the season
Common mistakes farmers make
What works—and what doesn’t
My focus areas include crop management, pest management, soil health, and cover crops. I’m especially interested in helping farmers improve productivity while keeping their farming systems sustainable.
Agriculture is always changing. My goal is to make that change easier to understand—and easier to apply in the field.