What Are Black Spots On Succulent Leaves?

Succulents are generally easy to grow. They are more resistant to diseases than most plants, they are hardy, and can live on a bare minimum diet. Also, succulents don’t need a lot of water. The ease to keep doesn’t mean that they don’t experience challenges. Black spots on succulent leaves are some of the symptoms to look out for so that you can take remedial measures to help your plant.

Why Are There Possibly Black Spots on Succulent Leaves?

The followings are some causes of black spots on succulent leaves and some of the actions you can take to remedy the situation.

Reason 1: Overwatering

The first thing that should come to mind when you ask yourself the question, ‘why are there black spots on my succulent leaves?’ Is water. This is because overwatering is probably the most common mistake people who keep succulents make. How do you tell which black spots are caused by overwatering? If the spots are mushy and soggy, then your plant is drowning. You are giving it too much water.

But how does a succulent drown? Succulents are adapted for arid and semi-arid regions and deserts. These are water-scarce areas and no matter how hardy a plant is, it will always need water. As a result, succulents spend relatively less water for their physiological functions while at the same time storing as much water as they can. They have specialized tissue in the stems, and leaves, and sometimes a succulent can have a caudex, which is an enlarged root that keeps the water.

When the succulent is having too much water, it keeps bringing water to the water storage tissue. This tissue, in return, bloats and ultimately explodes. The exploded tissue makes way for fungi to infect the plant thus the black spots as the leaves rot in the infected places.

How do you save a plant from black spots on leaves due to overwatering?

It might be possible to save the plant by just reducing the amount of water you are giving it to drink. In fact, if you notice these mushy black spots on the leaves you can stop watering the plant entirely for a time. However, you need to be sure that the roots are still healthy. Succulents’ roots are unlikely to be healthy if the pottage was waterlogged due to overwatering. However, if the substrate on which the succulent is planted is sufficiently pervious, the roots may have survived.

You will need to unpot the succulent to check the roots. Re-pot it and go easy on watering if the roots are healthy. If the roots have rotten, the plant can’t be saved. However, you can cut off the damaged parts and use the good parts to propagate new plants.

Reason 2: Fungus Infections

Fungal infection on the leaves usually manifests in the form of black spots. It is often referred to as ‘sooty mold’ due to the powdery black stuff that grows on the leaves when the plant is infected. The fungus scientific name is Capnodium citri. It is a saprophytic fungus which means it feeds on decaying matter. This fungus develops on the surface feeding on the structures of your succulent that are rather rich in carbohydrates.

The infection starts slowly with the fungus forming tiny black spots on the leaves of your succulent’s leaves. Yet as they continue feeding and reproducing, the spots get bigger and bigger if no treatment is offered. Ultimately Capnodium citri forms a black fil that is very evident on the entire leaf surface. This condition is usually prevalent where insect pests such as aphids, mites, and mealy bugs are present. Their feeding on the plant gives the fungus access. Destruction of chlorophyll by fungi inhibits photosynthesis in the plant weakening it and delaying development in the plant. This means that sooty mold always accompanies other pests and you need to deal with these other pests to treat them.

How does one get rid of sooty mold fungal infection? You can do it in the following clear stems.

1. Removing vanguard pests such as aphids, scale insects, and mealybugs using an organic contact pesticide: You can spray them with ginger spray, pepper, or neem oil. Organic pesticides are recommended because they are practical and are not as toxic to humans as synthetic ones. The consideration of toxicity is critical because some of these plants grow indoors.
2. The removal of the black soot from the leaves: You can remove the soot physically if the leaves aren’t too far gone: However if a much larger surface of the leaf is infected, you should go ahead and remove it. Pruning may be necessary at this juncture. You can remove the soot by cleaning each affected leaf with water and potassium soap and then dry the leaf gently with a dry cloth. You can use copper-based fungicides if the soot proves too stubborn for soapy water. Ensure you move the plants outdoors before spraying them since these fungicides are toxic.

Read more: How To Treat Fungus On Succulents.

Reason 3: Water Warts

Water warts are primarily a result of too much humidity in the air. Succulents are desert plants or at best adapted for arid and semi-arid regions. This means that even if you don’t water the succulent, they are still vulnerable to water warts as their leaves experience excess humidity.

It is a fungal infection that appears like a black wart on the surface of the leaf. You need to apply fungicides on your succulent to get rid of the infection. You can keep the issue from recurring by keeping regulating the amount of humidity your plant is experiencing if possible. If regulation is impossible, apply fungicide on the succulent weekly as a deterrent measure. Also, reduce the amount of water you are feeding your succulent.

Reason 4: Rot

Rotting is one of the worst things that can happen to your succulent. If it occurs, you will notice your plant has black spots on the leaves, stem, and roots. Rot is usually caused by a fungus which in turn finds its way into the plant through injuries that happen internally or externally. You can manage rot by removing the infected parts if the problem is not too extensive. If the damage is too great, you will have to destroy the plant or remove the unaffected parts for propagation. Besides the black spots, you can tell the plant is rotting from the smell and sogginess of the affected parts.

Related resources:

• What Is Succulent Root Rot & How To Fix It
• Succulent Stem Rot – How To Save Succulent With A Black Stem

Reason 5: Too Much Sun

Not all succulents are sun-hardy and even the sun-hardy, it isn’t to the same degree. The vast majority of succulents won’t withstand sunburns when the heat gets to 40^oC (104^oF). If you put a succulent under direct sunlight in these conditions, it will likely suffer sunburns which often manifest in black or brown spots on the leaves. Leaves usually suffer the worst of it due to their orientation and wider surface area.

Reaction to intense sunlight varies from succulent to succulent. Some will have a change in foliage color before they start showing sunburns. Once sunburns occur on the leaves, there is no remedy for them, you will just have to allow the affected leaves to outgrow the damage.

When you notice your plant getting sunburns, the best thing to do is move it from direct sunlight and position it under a shade. This will ensure it gets no more sunburns while giving it an opportunity to heal from previous injuries. You can make a shade on location if your succulent pots are too hard to move. Just ensure your plants are protected from the sun. Also, you may have to choose between allowing the leaves to outgrow sun damage or removing them altogether.

A guide on how much sunlight is enough for succulents >>

Reason 6: Frost

Most succulents are not cold-hardy, only some species in the Sempervivum genius can endure the frost. Exposure to frost causes black spots on the succulent’s foliage. The best way to deal with succulent frostbite is by protecting them. You can protect the succulent by moving them indoors when temperatures go below their tolerance threshold. If the winter isn’t too cold, you can cover your succulent using a winter cloth for the duration of the threat. It is vital to find out the level of cold your succulent can endure before planting them. Avoid any plant that wouldn’t survive the sustained winter temperatures of your area especially when growing it in a garden outdoors.

Reason 7: Too Much Fertilizer

The need for additional feeding exists for some succulents. Some will need additional phosphorus, nitrogen, or some other mineral according to their needs. It is vital for you to know when to feed the plant and how much fertilizer to feed it. Never feed the succulent during its dormancy season because chemical salts from the fertilizer accumulate in the soil as the plant is not taking it up.

The accumulation of these soils causes chemical burns in the roots and the rest of the plant including leaves. Burns manifest as black spots. Fertilizer has this same effect on the plant if too much of it is fed even in the right season. Some succulents need to be fed weekly during the growing season, some monthly, and some annually. Also, the concentration of the fertilizer varies from species to species. Find the need of your species and feed it accordingly.

You can deal with the problem if it has already occurred by stopping to feed the succulent, the black spots may just disappear as the plant heals. The other option is to water the plant thoroughly, the water should dissolve the chemicals in the soil and reduce their concentration. You may decide to repot the plant so that you give it an entirely different substrate.

Reason 8: Virus

Succulents can suffer from viral infections that can manifest as black spots on the leaves. Spots from viral infections tend to form in circular patches. It would help if you treated the virus early enough to ensure it doesn’t spread to the rest of the plant.

Reason 9: Pests

Pests such as aphids, mealybugs, scales, spider mites, whiteflies, slugs, and snails are may attack your succulent and feed on it. They feed on the succulent primarily by sucking the sap from them. The places where they attach as they suck the plant’s juices usually show injuries as black marks. The more pests there are in the plant, the more spots there will be on the leaf’s surface.

How to Prevent Black Spots On Succulents?

Effective preventive measures for these black spots depend on their causes. For example, you can keep your plants from getting spots by watering them sparingly. You can use the soak and dry method where you water the pot thoroughly and then allow water from that drink to dry out before giving it another drink. Planting your succulent on previous soil is another preventive measure. The soil should have such gravel content that it can allow excess water to pass through leaving only moisture in the soil.

Also, ensure you plant the succulent in a pot with drainage holes so that excess water can find its way out. Terracotta pots are the best in this regard because, besides the drainage holes, they have a breathable membrane that allows the evaporation of excess water.

You can keep fungal infections at bay by controlling pests such as mealybugs, scale insects, etc. Spray your plant with systemic pesticides such as neem oil to make the succulent unpalatable to these pests. This way you will keep them from being infected by pests. Spray organic contact pesticides on the succulent immediately after you notice even a single one on your succulent. It will keep them from reproducing. Another approach to pest control is isolating any infested plant to prevent it from infecting others. By controlling the pests, you will protect your succulent from the black spots caused by pests and the ones caused by fungus.

Related resource: Best Pest Control For Succulents.

It is easy to prevent the black spots caused by sunburns and frost bites. Find out how much the plant can tolerate and move it when weather conditions exceed this threshold. Concerning viral infections, isolate and treat any affected succulent and destroy any whose condition proves stubborn. You will save other succulents in your garden by doing this.

Read more: What Are White Spots On Succulents?

Final Words

Protection of succulents from black spots on the leaves is a better approach than treating them. As you may have noticed, prevention is as easy as following the husbandry rules which are not difficult anyway. Keep your succulents healthy and looking good by growing them in the right environments.