Black Spot on Leaves – Causes and Treatment

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Plants can help transform the dreary corners of your office and home into something cheerful and bright. You may be giving your plants lots of attention, but are you still having issues with plant health and appearance? One of the most common problems you may notice is black spots on the leaves of your plants.

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Here in this article, the causes of these black spots and potential solutions will help keep your plants black-spot-free.

What are Black Spots Found on Leaves

Black spots are not a cause for celebration. However, they do not automatically spell doom for your plant. The damaged leaves don’t die, and they often continue functioning.

The blackspots can be of different shapes and sizes. Some of them are round, while others have irregular edges. it is one of the common plant diseases. Although they are unlikely to disappear from the affected plant, new leaves will be spot-free once the cause is identified and remedied.

Causes for Black Spots Found on Leaves

A few reasons for black spots are serious, so you should not ignore them. The treatment varies as per the cause, so it is crucial to figure out the problem.

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The best method to prevent black spots is to keep the plant healthy. A robust plant is more resistant, and it will also recover and replace damaged leaves with fresh vegetation more quickly.

Overwatering the Plant

Overwatering of plants is the most common killer of houseplants today. The appearance of black spots is the plant’s way of calling for help. Damage from overwatering of plants begins with the roots and then moves upward. If the leaves are impacted, the plant is close to dying, and you must act fast.

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To verify that overwatering is the cause, you need to unpot the plant and look at the roots. If the roots are brown, black, and mushy or have a foul smell, your plant has been overwatered and requires assistance.

You can chop off the damaged roots and change out the soil in the pot. Ensure that issue doesnot reoccur by choosing well-draining soil.

Age Of the Plant

Sometimes, black spots aren’t caused by anything. They are symptoms of old, worn-out leaves. The natural deterioration occurs as a plant eliminates older leaves and transports the nutrients to other plant parts that are still growing. If age is the reason for the black spots, they should be exclusive to the bottom leaves. Additionally, the natural decline does not necessarily affect multiple leaves simultaneously. 

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You can slow down the aging process if you take superior care of the plant. You can do this by cleaning the leaves and rotating them in the sun.

Fungal Infection

If the plant suffers from a fungal infection, black spots on leaves will appear. Each plant is vulnerable to different types of fungal infections. The treatment for fungal infections is almost identical for all kinds of fungus.

Fungal pathogens thrive in wet conditions. They spread quickly due to drips and splashes. The key to solving the issue is preventing or stopping splashes and drips. The spores of the fungus can remain inactive for quite some time till they get activated by water. If a fungal infection is present, the plant is probably too moist, or the water has stayed on the leaves too long.

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You need to keep the plant drier and ensure the leaves don’t remain wet. Keeping the plant dry will help prevent and simultaneously treat the black spots on the plant leaves. The following tips that can help with this include:

  • You can give water to the plant at the base, not the top.
  • You can water the plant earlier during the daytime.
  • Ensure that area has plenty of ventilation in the area.
  • It would help if you did not mist the leaves.
  • You need to remove the affected leaves to ensure that the fungus doesn’t continue to spread. 

Once corrected, the fungus will not cause any permanent damage to your plant.

Viral and Bacterial Infections

Black spots can be bacterial or viral disease symptoms. If bacterial or viral infection infects plants, they will be stressed.

If you think that bacterial or viral infection is the cause of the black spots on your plant’s leaves, you must remove all the affected leaves. Some other tips for managing a bacterial or viral disease include sanitation and prevention.

You can do the following to help by

  • Keeping the plants that are not diseased away from those that are.
  • Sterilize any tools in between uses.
  • Give your plant extra attention and care.


A pest infestation can also cause black spots on the leaves of your plants. The most common offenders include mealybugs, spider mites, scale, and aphids. If you hose them off, the pests will leave your plant, and then use an eco-friendly pesticide like horticultural oil or insecticidal soap.

Least Likely Causes Of Black Spots On Plant Leaves

Some of the less likely reasons for black spots are as follows.

  • Nutritional Deficiency – Lack of nutrients can cause leaf streaking and spotting. The color of the damage is typically yellow to brown.
  • Sunburn – Intense direct sunshine can scorch and damage leaves. Sunburn usually results in bleached foliage or crispy brown splotches on the leaf’s surface.
  • Low Humidity – Low-Humidity stress causes dry spots and patches on leaves, besides slow growth and a dull appearance.
  • Cold Temperatures or Drafts – Plants stressed from cold or drafty conditions can develop spotted or otherwise marred foliage.
  • Water Quality – Leaves can become unevenly discolored if your watering source is highly mineralized or your plant is sensitive to contaminants.

How to Cure Black Spots on Leaves 

Usually, black spots are mainly a cosmetic issue, but they can be detrimental to the plant’s health in severe cases. Luckily, it is easy to cure black spots on plants by using homemade fungicidal and anti-bacterial solutions to kill the spots at the right source.

Step 1: Combine three tablespoons of apple cider vinegar with one-gallon water in a lawn and garden sprayer. Spray the plants with this vinegar mixture every morning until the black spots disappear.

Step 2 -Spray down the infested plant with water from a water hose. Spraying will loosen the fungus’s hold on the plant. Mix one tablespoon of baking soda, two and a half tablespoons of vegetable oil, half a tablespoon of castile soap, and one gallon of water in a garden sprayer. It would help to thoroughly cover the plants with the mixture weekly until the spots dissipate.

Step 3: Simmer eight ounces of elder leaves in sixteen ounces of water for half an hour. Strain the leaves and combine the liquid with one tablespoon of castile soap and sixteen additional ounces of water. Mix them well and apply to afflicted plants and spray once weekly until the black spots are cured.

Step 4: Mix 3 ounces of minced garlic with one ounce of mineral oil and let it soak for one whole day. Strain out the garlic and save the garlic oil in a glass container. Combine one tablespoon of fish emulsion with sixteen ounces of water and store in a glass container. Mix two tablespoons of garlic oil with one ounce of fish emulsion and spray on afflicted plants to cure black spots.

Step 5: Combine one part water with one part milk in a lawn and garden sprayer. It would be best to spray the infested plants with the mixture once every three to four days to eliminate black spots. The milk changes the acidity of the surface of the leaves, like apple cider vinegar. Due to this, it becomes harder for black spots and fungus to take hold and live on the plant.

Fungal Treatments for Black Spots on Leaves

Besides removing spotted leaves and keeping the leaves dry, it’s good to treat the fungal infection directly. There are several approaches to fungal treatment:

Fungicides – You can use some effective fungicides available on the market. These come in convenient spray bottles. Some of the brands claim to be organic. Commercial fungicides can treat a limited infection of a few plants, but they are expensive for more significant outbreaks or landscape plants.

Neem Oil – You can use Neem Oil as a natural means to control pests. It is an all-natural treatment that also contains various kinds of fungus. It smothers fungi spores, thereby preventing their spread. It’s necessary to coat the leaves of affected plants for maximum effect and best results.

It is safe for the environment and most plants, but it can burn foliage exposed to direct sun. You must not use it on the stressed or very young specimen.

Home Remedies – An economical and straightforward treatment is traditionally made by mixing a tablespoon of baking soda in a gallon of water. Add a half teaspoon of insecticidal soap or horticultural oil to make it stick to the plant.

Spraying the fungus with this mixture changes the leaf surface’s pH and creates an unlivable environment for the fungus. It costs only pennies per gallon.


Black spots are the last thing you want to see on our beautiful plant’s leaves. It isn’t uncommon, though some plants are more prone to the issue. Several issues can lead to black spots on your plant’s leaves. To fix the problem, you must figure out the cause of the problem to provide the correct type of treatment to get rid of them and restore your plant’s health.

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