Black Sooty Mold on Mango Tree: Fungus Causes & How To Treat

Black sooty mold develops on a sticky substance called honeydew, which is produced by different insects that feed on plants.

Though sooty mold doesn’t directly harm the plant, its presence can indicate an underlying pest problem and negatively impact photosynthesis.

To treat black sooty mold on a mango tree, you must control the insects producing the honeydew that promotes mold growth.

The sooty mold can be washed off with a strong stream of water or soap and water mixture. Regularly check for pests, and apply insecticides when necessary.

When your tree is indicating that there is a problem, it’s important to act quickly before the problem grows.

Key Takeaways

  • Sooty mold usually appears on mango trees due to fungi that grow on honeydew, a byproduct excreted by certain insects as they feed on plant sap.
  • The primary strategy to control sooty mold growth is to manage and reduce populations of honeydew-producing insects, such as aphids, whiteflies, and soft scales.
  • While sooty mold will naturally flake off over time after the sucking insects are eliminated, it can be manually removed using a strong stream of water or a mild soap solution.
  • Keeping the mango tree healthy through proper fertilization, watering, and pruning can make it less susceptible to pests and, by extension, sooty mold.

Black Sooty Mold on Mango Tree

Mango trees can sometimes fall victim to an unsightly issue known as sooty mold.

Sooty mold, a species of fungi that grows primarily on the sticky compound known as honeydew, might colonize many types of surfaces.

As this mold grows, it creates a black, powdery layer on the plant parts, especially the leaves.

Honeydew, a sweet and sticky liquid that plant-sucking insects excrete, acts as a magnet for this type of fungus, indirectly damaging the plant by coating the leaves.

The mold uses honeydew produced by several kinds of insects as a food source. Thus, the larger the pest population is, the more black sooty mold you’ll find.

Black Sooty Mold Symptoms

When a mango tree is affected by sooty mold, its leaves, twigs, and sometimes even fruits exhibit a black, powdery substance on the surface.

This mold usually grows in patches and can spread to cover large sections of the plant, making it look as if it’s been dusted with black soot.

The affected plants often have leaves that appear dull, not glossy, as they are coated with sooty mold fungi.

If left untreated, these coated leaves also might prematurely age, and their ability to undergo photosynthesis efficiently is inhibited. This is because the mold covers the leaf surface, hindering light penetration.

Mango leaves heavily infested with black sooty mold.

Black Sooty Mold Causes

The primary cause of black sooty mold on mango trees, or on trees and shrubs in general, is the presence of honeydew.

This sticky substance is excreted by certain insects like aphids, whiteflies, and soft scales as they feed on the sap from a plant.

These insects assimilate what they need from the large volume of fluid they ingest and excrete the rest as honeydew.

This honeydew, deposited on plant parts and other surfaces, accumulates and acts as a food source for the sooty mold fungi.

Additionally, ants often tend to these honeydew-producing insects, protecting them from predators in exchange for honeydew, further exacerbating the pest problem.

Damage Caused by Black Sooty Mold

While sooty mold doesn’t directly harm the plant by penetrating its tissues, it can indirectly damage the plant by coating the leaves to the point that they can’t photosynthesize properly.

A thick layer of sooty mold can limit the amount of sunlight that reaches the leaf surface, disrupting the plant’s energy production.

Over time, if not addressed, the health of the tree may decline, leading to stunted growth, reduced fruit production, and increased susceptibility to other diseases.

Moreover, the aesthetic value of the tree is also compromised, making it less appealing in a garden or orchard setting.

Black Sooty Mold Treatment

The treatment for black sooty mold begins with managing the insect creating the honeydew, which is the primary source of food for the mold.

Identifying and controlling honeydew-producing insects can be done through natural predators, insecticidal soap, or targeted insecticides. 

Natural predators of these pests, such as ladybugs and lacewings, can offer biological control. If infestations are severe, consider using insecticidal soap or other specific insecticides.

Once the number of insects that produce the honeydew is reduced, the mold will gradually diminish as it loses its food source.

For immediate relief, sooty mold can be washed off with a strong stream of water or soap and water solution, especially mild soap and warm water.

Additionally, pruning can be helpful. Removing infested plant parts can reduce the pest population and subsequently decrease honeydew production.

Furthermore, maintaining good garden sanitation, trimming limbs touching buildings or the ground, and ensuring proper fertilization and water can help keep these pests at bay.

Pests That Cause Sooty Mold Growth

Sooty mold growth on mango trees and other trees and shrubs is not a direct result of the fungus itself but rather an indirect consequence of certain insect activities.

The mold thrives on honeydew, a sweet and sticky compound. But how does this honeydew come to coat the leaves in the first place? The culprits are often specific honeydew-producing insects.

Aphids

A plant stem completely covered with green aphids.

Aphids are tiny plant-sucking insects that are among the primary pests responsible for excreting large volumes of honeydew.

They feed on the sap of plant parts, especially the younger leaves and stems. From the sap, these insects extract and absorb what they need and excrete the rest as honeydew.

Aphids come in various colors, and their populations can explode in favorable conditions, leading to a significant sooty mold problem if not checked.

Whiteflies

Several whiteflies congregating on the stems of mango tree leaves.

Similar to aphids in their feeding habits, whiteflies are another major pest that can produce the honeydew sooty molds thrive upon.

They are tiny, white-winged insects that often reside on the undersides of leaves. When infested plant parts like leaves are disturbed, you might see a cloud of these tiny insects flying off.

Whiteflies can lead to dual problems: direct damage through feeding and indirect damage through the production of honeydew, which, in turn, fosters mold growth.

Scale Insects

Several soft scale insects on a green leaf.

Soft scales are yet another group of honeydew-producing insects. They have a more domed appearance than aphids and can vary in color.

These insects excrete honeydew as they feed on the sap from a plant. Unlike other pests, they often remain stationary on a particular spot once they start feeding, making them appear like a part of the plant.

Ants

Ants farming aphids on a plant stem.

While ants do not produce honeydew, they play a pivotal role in the spread and protection of honeydew-producing insects.

Ants farm these pests, especially aphids, tending to them and protecting them from predators. Why? Because the honeydew acts as a source of food for them.

By doing so, ants inadvertently promote the increase of honeydew on plants, thereby increasing the potential for sooty mold growth.

To manage sooty mold, it’s essential to keep ants out of trees and away from honeydew-producing insects.

How To Remove Sooty Mold From Mango Leaves

Sooty mold, as alarming as it looks, is often more of a nuisance than a death sentence for your mango tree.

Although sooty mold doesn’t pose a direct threat to the leaf’s cellular structure, it does inhibit photosynthesis due to the darkened surface of leaves.

Understanding its nature and life cycle is essential for effective management.

Natural Shedding

First and foremost, it’s crucial to know that once the source of honeydew (typically sap-sucking insects) is eliminated, the sooty mold will gradually lose its food source.

Over time, without this sustenance, the sooty mold will dry up, become flaky, and naturally shed off as the leaves grow and as the rain washes them.

This process might take time. Patience is required as nature takes its course to remove the mold.

Water and Gentle Agitation

For those looking for quicker results, using a strong stream of water can be highly effective. A garden hose with a spray nozzle can help dislodge the sooty mold from the leaves.

However, be sure to use this method in the morning or early afternoon to allow the leaves to dry properly before nighttime, preventing any potential for other fungal issues.

Soap and Water Solution

If water alone doesn’t do the trick, a mild solution of soap and water can help. Mix a few drops of mild soap in a bucket of warm water. Using a soft cloth or sponge, gently scrub the affected leaves.

The soap will aid in breaking down the mold’s structure and make it easier to remove. After scrubbing, rinse the leaves with clean water to remove any soap residue.

Maintaining a Healthy Tree

The healthier your mango tree, the less susceptible it will be to pests and the consequent sooty mold problem.

Regularly fertilize and water your mango tree, ensuring it gets all the necessary nutrients.

Prune any dead or diseased branches, ensuring proper airflow and sunlight penetration. A healthy tree can resist pests better and, by extension, reduce the chances of sooty mold appearance.

Ongoing Vigilance

Remember that the recurrence of sooty mold is directly tied to the presence of honeydew-producing pests.

Regularly inspect your tree for signs of these pests, and manage them promptly. Prevention is always better than cure.

Frequently Asked Questions:

What Is the Cause of Mango Sooty Mold?

Sooty mold on mango trees results from the growth of specific species of fungi that thrive on honeydew.

This honeydew is excreted by various plant-sucking insects, such as aphids, whiteflies, and soft scales.

The presence of these insects and the consequent honeydew deposits lead to the growth of sooty mold.

What Kills Black Sooty Mold?

Eliminating the source of honeydew, which are honeydew-producing insects, is the primary step. Once these pests are managed, the sooty mold loses its food source and will eventually flake off.

For quicker results, affected leaves can be cleaned with a strong stream of water or a mild soap and water solution.

What Do You Spray on Black Sooty Mold?

A strong stream of water can help dislodge sooty mold from leaves. If that’s insufficient, a mild solution of soap and warm water can be used to gently scrub the affected areas.

It’s essential to rinse off any soap residues thoroughly after cleaning. Keeping the tree healthy and free from honeydew-producing pests will prevent mold recurrence.

Does Neem Oil Get Rid of Sooty Mold?

Yes, neem oil can be an effective treatment, not directly against sooty mold but against the insects that cause honeydew production.

By managing these insects, neem oil indirectly reduces the possibility of sooty mold growth. It’s a natural insecticide that targets pests without harming beneficial insects.

What Is the Black Stuff on My Mango Tree?

The black patches are likely sooty mold fungi growing on honeydew deposits. Honeydew is a sticky liquid excreted by certain insects like aphids, whiteflies, and soft scales as they feed on plant sap.

The mold uses honeydew as a food source, leading to the characteristic black patches on affected parts of the tree.

Closing Thoughts

Black sooty mold on mango trees is primarily a cosmetic issue, but its presence indicates an underlying insect problem. By addressing the insects, you’ll inherently manage the sooty mold problem.

Regular monitoring and prompt action, like the use of insecticides and ensuring trees are free from ants, will help your mango tree remain healthy and vibrant.