Cactus Plant Turning Brown and Yellow: Cause and Cure

Cactus are low-maintenance plants that have become popular houseplants these days. They don’t need much care to grow but a few issues are there. Cactus turning brown is one of them.

Though it is not a big problem. If you find your lovely cactus turning brown you should start treatment immediately which is as low cost as the maintenance of the cactus.

There are a few reasons which propagate a cactus turning brown. All of them have different solutions.

The reason behind a cactus turning brown

Whenever one finds their cactus turning brown the first thing coming to their mind is why it is turning brown. There are a few reasons one can find behind it. 

1. Overwatering

Cactus are desert plants and don’t need much water to live. If someone overwaters them then that can be harmful to the plant.

Overwatering will fill the air spaces in the soil. It kind of suffocates the roots by stopping them from aeration. Overwatering also helps in creating the perfect thriving condition of fungi and bacteria which causes diseases to the plant.

Ultimately, the roots rot due to it and disease-spreading organisms get in the plant’s body.

Symptoms

The bottom of the cactus turns brown and mushy.

Solution:

Stop overwatering. Keeping the plant on the schedule will not help in this case. One should depend on soil check for this purpose. Check your plant’s soil before watering it. If you find its top 2 inches wet, don’t water it.

It could happen that you are watering your cactus once in a few days in summer, once in a month in winter and never in monsoon. To check the humidity of the soil, one can use a soil probe also.

2. Poor drainage  

poor drainage cactus pot

Cacti should get put in soil which doesn’t retain water for long. Because wet soil makes the root rot which allows the disease-spreading fungus and bacteria to enter the plant’s body.

Solution:

Don’t use heavy soil as it remains wet for long. Use cactus and succulent mix as soil. One can add perlite with soil to improve the drainage. The soil must have sand and small stones mixed in it.

Don’t use a bigger pot than the plant need. Big pots can retain much water. Just provide a pot as big as the plant wants to fit in. Choose a pot that has a hole in the bottom for drainage purposes.

If one wants to plant the cactus outside, first choose the perfect soil for it. Or else prepare it by mixing sand and small stones proportionately. It is better to plant it on a mound or slope for better drainage.

3. Injuries 

Unhealed injuries of your cactus can get it sick. So, heal it as soon as possible.

Even take care while repotting because it can leave a root injury.

Injuries and cuts are the ways for the pathogens to enter the plant’s foliage. They can make the bottom of the cactus appear brown and mushy. Then it keeps on growing upwards making the cactus turn brown.

Solution:

Use a cleanser containing bleach to dust on the wounds till it turns into scabs. It can take about a week but might take longer if the wound is big or grave.

4. Insects and pathogens 

There are various insects and pathogens who harm cacti and make them rot and so, the cactus grow brown.

There are a few kinds of fungus and bacteria that make cacti diseased and rotten. In this case, the plant can start turning brown from other parts rather than roots also and it starts spreading.

Fungus infections are very common in cacti. The lesions caused by fungus infections can be brown and ooze brown sap also which is a symptom of severe infection. These lesions are round, flat, irregular and any other shape.

The plant can get contracted with fungus’ spores via air, soil, and water.

Solution of fungal infections

Fungal infections are hard to prevent. Mild infections can be treated by fungicide though. But severe infections kill the cacti. 

One can spray Copper Sulphate fungicide mixture on their cactus to remove fungal infections

An insect called the cactus longhorn beetle causes serious harm to cacti.  Its larva prepares burrow in the plant. It thrives by eating cactus’s water storage tissues. Due to it, the cactus grow brown.

It introduces the plant to new diseases alongside eating it from inside and making it rot which ultimately results in turning the cactus brown. The cactus starts turning brown usually from its base in this case.

There are a few scales and mites that are brown in color that can build a colony on your plant’s body. They are brown in color and too small to get recognized. So, they might look like brown spots only and you can find your cactus turning brown due to their infestation.

Scales thrive on plant juices and thus weaken the plant. Red spider mites are red in color and very small in size.

The symptom of their infestation is white spots at the top of the plant’s body, which will turn rusty brown gradually. These mites can kill your plant by eating up its outer layer of tissue.

Solutions to insect infestations

Treat wounds of the plant properly to stop the pathogens from entering the plant’s body. Don’t overrated, so the roots will remain healthy which will obstacle the pathogen invention.

For the cactus longhorn beetle, the most effective measure one can take is handpicking the adult insects from the plant and putting them in soap water or insecticides.

To get rid of scales pore some weak solution of mild detergent over the plant. For large infestations of scales, use malathion insecticide. One can suffocate the scales to death by dabbing horticultural oil over them with a cotton swab also.

One can use miticides to treat large infestations of red spider mites. For a few mites, shower your cactus with a strong flow of water.

5. Corking

In the case of corking the tissues of the cactus become stiff and bark-like. Its colors are brown. So, the cactus turn brown also.

It starts from the base of the cactus and moves upward. Corking is the natural process to show that the cactus is aging.

6. Sunburn

People think cacti are fond of sunlight as they are habituated with harsh and hot weather but that’s not true actually.

There are few cacti species that are happy to be indoors. If you put them under harsh sun for long, they can get harmed. In this case, due to the scorching sun, the top of the cactus turns brown.

If you are keeping your cacti in shade for a long time and expose them suddenly to the sun, even if they are outdoor cacti; they will get brown at the top and the portion facing the sun.

Sunburn appears like a whitish spot at first. Severe burns look brown and they last forever. It can damage the plant seriously.

Solution:

Keep indoor cacti away from direct sunlight for long. Try to keep them indoor, near the window where they can get adequate sunlight indirectly. Don’t expose cacti, who are kept in shade for a long time, to direct sunlight. They can get sunburned.

There are few species that are not allowed to be exposed to direct sunlight at all. So, please know about the species before putting it in direct sun.

Only cactuses with white spots can get treated by putting them in the shade as they are not damaged immensely. Brown severe spots can’t get treated.

Don’t transfer your plant directly to the hot sun. Try to move them gradually to sunnier places. This way you can avoid sunburn and prevent your cactus from turning brown.

How to revive a brown cactus 

It is very easy to take care of cacti. As they don’t need much food and water, they can get reared in a very economic way. They don’t even want much time from one.

But few mistakes like overwatering can harm them very hard. But still, if your cactus has turned brown you can get it back to the right track. One just needs to follow these few steps.

1. Treatment of rot

Rot can turn a cactus brown and mushy. Cactus rots are caused by diseases or insects or water which have got inside the plant’s body through any wound.

A cactus can turn brown and mushy due to overwatering. Overwatering causes damage to the roots of the plant which might become severe if left untreated and can kill the cactus.

If one finds brown spots at the bottom of the plant and if that potion is mushy, un-pot the cactus. For that wrap a few layers of newspaper around the plant to avoid bruises from its thorns.

Pull out it gently. Brush away soils from its roots gently and look for the black or brown roots. If most of the roots are still unaffected then it is in a better stage and can get treated easily.

But if one finds most of the roots damaged then the condition is severe and needs longer to get healed.

For not-so-severe conditions, one needs to cut away the damaged roots and let the cactus dry out of its pot. The soil in the pot might get replaced as it has more water than the cactus need. It also might not be the right kind of soil a cactus needs. So it must get replaced.

Once the cut of the cactus gets healed and turns into a scab, put it in the soil and start watering it as much as it needs. Overwatering again can make it face the same issue.

But if the condition is severe and the bottom of the plant is terribly rotten, cut off the top of the cactus with a clean and sharp knife. The cut must be made 2 inches above the rotten place.

Now allow it to dry and form a scab out of its pot. It can take 1-3 days to heal properly. Keep it away from direct sunlight and cool temperature. One can sprinkle sulfur powder at the cut also. Sulfur powder prevents infections and works as a fungicide.

In between, change the soil of the pot with a dry cacti mix. Plant the cactus in the fresh soil once it gets properly healed.

Put it deep enough so it does not get toppled over. Water once in a week when it’s forming new roots there. Once it gets finely rooted in the new soil, water it only when the top layer of the soil is totally dry. Overwatering can damage it badly again.

Stem rot

The cactus can rot from the top also. It is called stem rot.

In this case, the plant starts rotting from its top portion which spreads towards the bottom. It can look like a small brown spot at the first stage. But deep inside the cactus’s body, it must be enough spread.

How to remove stem rot

Choose a sharp pruning tool for the cutting. Clean and sterile it properly. Try to dip it in rubbing alcohol after every cut. This way the spread of diseases can be stopped.

As stem rot gets spread widely inside but has little exposure outside. One should remove it layer by layer. Even the portion which looks healthy from the outside might be rotting inside the stem. As one moves downwards the plant by removing the layers, they will find the rot getting thinner gradually.

But remove all the brown mushy material from the plant. Even a single dot of rot can spread and rot the whole plant.

If the cactus is put outdoor, make the last cut in an angular way. So that water won’t settle on its top. Keep it under shade to protect it from rain until the wound becomes a scab.

Why is the cactus turning yellow?

cactus turning yellow

There are several reasons why a cactus turns yellow.

  1. Inadequacy of light:  Due to the scorching sun, a cactus can turn yellow.
  2. Wet soil: If the soil doesn’t dry easily, it can make your cactus rot. As result, the cactus turns yellow.
  3. Lack of Nutrients: If the plant doesn’t get the proper nutrients from the soil, it can turn yellow.
  4. Improper watering: If one provides it with more or less water than it needs, it will turn yellow.
  5. Weather issues: Cacti are habituated with desert-like weather which is hot in the daytime and cold at night and the atmosphere remains dry. So, humid weather can make the plant rot and turn the cactus yellow.
  6. Bug infestation: Bugs can make big colonies and destroy the plant’s health by turning the cactus yellow.

Taking precautional measures in all these issues can solve the problem

Care for pruning

Once you prune your cactus, you should keep an eye on them as they go through a stage afterward. If they develop a new rot even after pruning, Apply the same steps to remove the new rot.

Once the wound gets healed, the plant develops new growth near the cut which adds new beauty to it.

Conclusion 

In spite of the above solutions of your cactus turning brown and yellow, it is not always possible to stop your plant. If the issue is terribly severe, you might not be able to solve that.

It might happen that the whole situation slipped out of your grip even before you had laid your hand on it. But don’t forget to try.

It’s very common for cactuses to turn brown or yellow and the solutions are also there. All it needs is your love and care for your cactus.

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