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What Are Black Spots on Leaves and How to Get Rid of Them?

Black Spots on Leaves

The beauty of a plant lies in its vitality. Lush green leaves make houseplants more attractive. Imagine dry, damaged, or wilting leaves – an eyesore, right? Well, the appearance of your plant can also tell you a lot about its health. 

For example, black spots on houseplants leaves indicate a fungal disease, pest damage, or nutrient deficiency. It is the last thing you want to see on your houseplants. 

So, what should you do if your plan is suffering from this issue?

This article will tell you the causes of black spots on houseplant leaves and how to get rid of them forever with simple home remedies. 

What Are Black Spots on Leaves?

Almost all trees and plants are prone to some type of leaf spot disease. Black spots on leaves are irregularly shaped marks on the surface of the leaves. They can be small clusters or large circular spots. It is also known as leaf spot disease.

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Common Types of Black Spots on Leaves 

Little black dots on outdoor plants or houseplants can be of different types. Let’s explore some of the most common types of block spot diseases:

  1. Leaf Spot Blight Disease

Blight is a type of black spot disease that affects young green shoots and does not infect older plants. A few examples of black spot blight disease include Aschochyta blight and Venturia blight. 

  1. Leaf Spot Canker Disease

Cankers are a type of infection that causes round and oval-shaped blackish spots on leaves and other parts of a plant. As the infection grows, cankers lead to wilting and the death of infected leaves.

  1. Leaf Spot Downy Mildew

Downy mildew infections are first noticeable as light green spots on the upper side of the leaf that turns brown to black with time. This black spot disease affects the undersides of the leaves in humid conditions. 

Identification of Leaves Spots 

Black spots on leaves come in a wide variety of shapes and sizes. Here is how you can identify black spots on plants: 

  • Leaf spots are usually seen first on the lower surface of leaves, where the leaves are shaded, and humidity is higher.
  • The spots appear randomly on the leaf surface.
  • Leave spots can occur on both surfaces of the leaves (upper and lower) in various sizes.
  • Small black spots signify a younger infection, while large black spots indicate an older infection. 
  • You can often see the pathogen in the center of large black spots such as fungal spores or spore-producing structures.
  • The shape of the spots on leaves can be rounded, or angular, sunken or raised and have fringed or smooth edges. 
  • The color of black spots can range from tan, brown, and black. 
  • Black spots on leaves of trees weaken the leaves to drop prematurely, causing the tree or shrub to lose its leaves.

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Symptoms Of Black Spots on Leaves 

As the name suggests, the first sign of black spots is irregularly shaped spots. They are usually tiny but can grow to 1/2 inch in diameter if the damage is severe. 

The condition worsens when the leaves turn yellow and die, dropping prematurely from the plant. If not treated timely, the entire plant gets infected which makes it defoliate

Causes Of Black Spots on Leaves 

Here are the leading causes of black spots on leaves: 

  1. Overwatering

Overwatering the plant is also a serious possibility of black spot disease. Overwatering can kill houseplants, and black spots may be the final cry for help.

Water damage begins at the root, and as the plant worsens, the leaves start to get affected. To rule out overwatering as a cause, unpot the plant and examine the roots. If the roots are mushy with a foul smell, your plant is damaged due to root rot. 

If the soil is dry and the roots are healthy with an earthy smell, check for other causes of black spots. 

  1. Age

Make sure your plant or foliage isn’t simply old and worn out. Natural deterioration is normal when plants get older. Aging usually affects the bottom leaves. 

To reduce natural decline, take extra care of your plant and ensure it gets optimal sunlight and water for maximum longevity.

  1. Fungal Diseases and Infections

Fungal infection or disease causes the majority of black spots on leaves. Fungal spores are activated by water, so fungal pathogens attack wet plants. 

Fungal spores quickly spread in humid conditions or when a plant is too moist. They cause black spots where the water has lingered too long on the leaves.

  1. Bacterial Infections

Sometimes a bacterial infection may also cause black spot diseases in plants.

Home Remedies to Treat Black Spots on Leaves 

Fungal infections are usually not fatal or dangerous to plants if addressed early on. You can prevent severe or permanent damage by correcting the cause. There are many effective home remedies for black spot fungus treatment

We have listed below the best ways to remove black spots and cure your houseplant! 

  1. Wipe With Neem Oil

Neem oil is one of the most effective home remedies for black spots on plants. It is a natural treatment for pest control. Neem oil is also used to control different fungal diseases in plants. 

The best thing about neem oils is that it is all-natural and does not kill the infected plant. Coat the foliage of the affected plant with neem oil to prevent the spores from spreading to other neighboring plants. 

Neem oil is a safe treatment for most plants but avoid use on outdoor plants or those exposed to extreme sunlight. 

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  1. Spray With Baking Soda Solution

For a simple and economical treatment, use a baking soda solution. Spraying the infected parts with this concoction will alter the pH level of the leaf surface which creates an unlivable environment for the fungus. 

Mix a tablespoon of baking soda in 2-3 liters of water and add half a teaspoon of horticultural oil or insecticidal soap. This solution will stick to the leaves and render the growth of the pathogen causing black spots. 

  1. Dampen With Chamomile Tea

Chamomile tea has sulfur which fights a certain kind of black spot-causing fungus. All you have to do is soak a tea bag of Chamomile tea in a bottle of water. Spray the concoction on the affected houseplant(s).

Note: Do not drench the plant. Only lightly mist the affected area.

  1. Cornmeal Keeps Black Spots at Bay 

Cornmeal stimulates the growth of a fungus that fights with the fungi causing black spots. Cornmeal is also rich in nutrients which strengthens the damaged plant. Take ½ cup cornmeal and sprinkle it on the affected leaves. Cover the plant with bark mulch.

  1. Cinnamon Fights Fungal Spots 

Cinnamon is a potent spice with many medicinal benefits for plants and humans. It is said to fight fungal leaf spots. All you have to do is rub some ground cinnamon on the black spots on leaves. Use a small quantity and only apply to the affected area as too much can burn the healthy leaves.

  1. Use Fungicides

Unfortunately, there are not many effective chemical treatments for houseplants. But you can use some effective fungicides to treat infected plants. However, fungicides are harmful to the environment. 

Many brands are now introducing organic fungicides. You can get them to treat fungal infections of houseplants. 

Note: Fungicides are a protective measure and should be applied before the infection worsens on the leaves. The timing of black spot fungicide application varies depending upon the plant and the cause of the disease.

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  1. Remove The Damaged Leaves 

If the black spot disease is severe, it is better to remove the affected leaves. Safely destroying the damaged leaves will prevent the infection from spreading to other parts and other plants. Moreover, if your plant is damaged beyond repair, just get rid of it. 

Tips To Prevent Black Spots on Leaves 

Treating a fungal leaf spot disease can be tricky, and all the home remedies in the world might not work. The best thing to do is to prevent black spots on leaves in the first place. 

Here are the best tip and tricks to keep your houseplants healthy and safe from infections that can lead to black spots: 

  1. Take Extra Care 
  • Keep The Plant Dry 

Keep the plant a bit dry and make sure the leaves are not wet for long. It is the best prevention for any kind of infection or disease as most pathogens are attracted to wet and humid conditions. 

  • Give Ample Sunlight 

Your plant will thrive if it is well fed. Make sure your houseplants get ample light and water for photosynthesis. A strong and healthy plant has the ability to fight or outgrow any infection.

  • Use Milk to Prevent Fungus 

Yup! Milk is an effective agent to fight fungus. When you coat the leaf surface with milk, the milk proteins and lactic acid prevent spores from embedding in the surface. Make a concoction with 1/3 cup of milk in 2 cups of water. 

Shake the mixture well before you spray it on the plants. Spray until the leaves are dripping. Unlike chemical fungicides, this solution is 100% safe to use on plants leaves. (And it doesn’t smell!)

  1. Improve Watering Habits 
  • Water At the Base 

Instead of watering the plant from the top, pour the water on the soil. Nestle the hose or watering pot at the base to avoid damping the leaves. You can also place the plant in a shallow water tray to make the soil soak the moisture up the roots from below.

  • Water During the Day 

Try to water your plants early in the day when natural light is at its peak. This allows the water to get absorbed quickly, and the plant remains dry. 

  1. Improve Air Circulation 
  • Provide Good Ventilation 

Ensure your indoor plants are kept in a well-ventilated room to air out the leaves. If you live in a humid environment, open the windows or take the plant to a balcony or any outdoor spot to let the air dry out any damp spots. 

  • Don’t Over Crowd 

Keep your plants at a proper distance from each other to allow them to breathe. If you group your plants close together, it can get humid. Moreover, if the foliage of one plant touches the other, it makes it easier for the infection to spread to other plants. 

  1. Prune and Groom Regularly 

Groom your houseplants regularly to remove aged leaves and increase light penetration. This will also improve air circulation throughout the plants.

  1. Prevent Invention from Spreading 
  • Remove Affected Leaves  

Treat affected foliage before the disease spreads to other leaves and destroys the foliage. You can reduce further contamination by discarding the affected parts safely. 

  • Sterilize Your Tools

The best way to prevent and manage bacterial or fungal infections is sanitation. Sterilize your plant tools before, between, and after uses. Just wipe them with isopropyl (also known as rubbing alcohol). 

FAQs

Should I remove leaves with black spot?

If you see black spots on the leaves, remove them and dispose of them. It is not necessary to disinfect the pruners, as long as you avoid touching the black spots with your hands. The same procedure should be followed for all plants in your yard or garden that are susceptible to black spot. The pathogen survives on plant debris and can reinfect any plant that comes into contact with it.

What causes black spot?

Black spot is caused by a fungus called Colletotrichum laccase. It causes black spots on the leaves of your plant and they can completely destroy your plant if not treated. There are many ways to treat black spot, but the best way is to prevent it from happening in the first place. To prevent this fungus from infecting your plant, you should make sure that the conditions are not favorable for it to grow.

How is black spot spread?

In the case of black spot, it can usually be spread by walking through an infected area and touching a plant that has black spot. With spores landing on your hands, you can then transfer them to healthy plants in your garden. This can lead to the infection of more plants and increase the spread of the disease.

Wrapping Up

There’s nothing more devastating for a plant parent than finding ugly black spots on leaves. You can take preventative measures to keep your houseplants safe from fungal infections. For example, keep the leaves dry as wet surfaces attract spores. 

God forbid if your plant does get infected, don’t you worry; this guide contains the best home remedies to treat infected plants. Unfortunately, if they cannot be saved, discard the infected leaves. 

Written by Chris Buckland

Hello, I’m Chris. I’m a houseplant expert. I have been Cultivating and Growing Houseplants for 20 years. Plants are like my children. I love to write about Indoor plants and share my experience. That's why I started writing everything I know about houseplants.

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