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How to save a rotting cactus

5 min read

How to save a rotting cactus


Cacti are like the tough, cool kids of the plant world. They have unique shapes and textures, they boast stunning and showy flowers, and they can survive in extreme conditions while requiring very little care. Cacti are symbols of strength and endurance; they only need minimal upkeep and they are perfect for our busy modern life. However, despite their hardiness, cacti are very fragile and vulnerable when it comes to rotting. 

Rotting is one of the most common complications for cacti lovers. Rotting can be a devastating issue, as it can damage or kill the plant if left unchecked. Signs of a rotting cactus include soft and mushy stems, discoloration and browning of the top, wilting and foul odor. When rot sets in, it can quickly spread to other parts of the plant, causing irreparable damage. It's essential to learn how to identify the signs of succulent rotting and take the necessary steps to prevent it from happening. 

What causes rotting in cacti?

Rotting in cacti is typically caused by excessive moisture due to overwatering or poor drainage. Cacti are adapted to survive in arid conditions, so they are sensitive to too much moisture. When a cactus is overwatered, the soil becomes waterlogged. Oxygen supply to the roots is reduced, which can lead to anaerobic conditions that favor the growth of anaerobic bacteria and fungi. These microorganisms can attack the root tissues, causing them to decay and die. As the roots rot, they lose their ability to absorb water and nutrients from the soil, which can cause the cactus to wilt and eventually die.

Physical damage is also a significant contributor to cactus plant rotting, as it can create wounds that leave the plant's inner tissues exposed to environmental factors that promote decay. Animals and insects that feed on cacti can also cause damage, leaving behind open cuts that increase the risk of rotting. These cuts can provide entry points for bacteria, fungi, and other microorganisms that can infect the plant and cause it to rot.

Physical damage is also a significant contributor to cactus plant rotting
Physical damage is also a significant contributor to cactus plant rotting

Bacteria is one common reason why your beloved cactus is rotting. One common bacberium is Erwinia carotovora. It causes soft rot in cacti, as well as in many other plants. Soft rot caused by Erwinia carotovora typically appears as a watery, slimy rot that causes the affected tissue to turn brown or black and become mushy. The bacterium can enter the plant through wounds or natural openings and can spread rapidly through the plant tissues.

Fungal infections and diseases can also cause rotting in cacti. Fungal diseases are often caused by overwatering or poor air circulation, which creates conditions that are favorable for fungal growth. Fungal and bacterial infections can also cause rotting in cacti, particularly if the plant has been damaged or stressed in some way. The most common pathogens that cause rotting in cacti are species of Fusarium, Pythium, Phytophthora, Rhizoctonia, and Anthracnose. These pathogens can infect the roots, stems, and leaves of the cactus, causing them to turn soft or mushy and eventually decay and rot. In severe cases, the plant may emit a foul odor as a result of the infection.

Moreover, overfertilizing might also make your cacti rot, as the excess nutrients can burn the roots and create an environment hospitable to bacteria and fungi that can cause rotting in the plant.

Type of rotting and how to save your cactus

Root rot

Signs of root rot in cacti may include soft or mushy roots, yellowing or wilting of the plant, a foul odor, stem bending (due to weak roots), and a lack of new growth. The plant may also appear to be discolored or have dark spots on the stem or leaves, and it may be more susceptible to damage from pests or diseases.

To save a cactus with rotting roots, it is important to act quickly. 

First, remove the cactus from the soil and carefully remove any rotting or dead roots using a clean, sharp tool such as a pair of scissors or a knife.

Next, allow the plant to dry out for several days until the cut areas have callused over.

Then, repot the cactus in a well-draining soil mix, making sure to avoid overwatering and providing good airflow around the plant to prevent further rot. It may also be helpful to treat the plant with a fungicide to prevent any remaining fungal spores from causing further damage.

Stem rot from top down

When a cactus is rotting from the top down, it can be a severe issue that requires prompt action to save the plant. Here are some steps you can take to try and keep a cactus that is rotting from the top:

First, you need to identify the affected area and remove the damaged tissue then use a clean, sharp tool such as a pair of scissors or a knife to carefully remove any damaged or rotted tissue. Be sure to cut away any brown or black areas, as these are signs of dead tissue that cannot be saved.

Next, allow the plant to dry out completely before treating it with any fungicides or bactericides. This can help prevent the spread of the infection. Once the cactus has dried out and callused over the affected area, you can treat it with a fungicide or bactericide. Be sure to follow the instructions on the product label carefully and avoid over-applying the treatment.

Finally, cacti need plenty of bright, direct sunlight to thrive, and they also require good airflow to prevent the development of mold and other fungal infections on the open wound. It may be helpful to move the plant to a brighter location or to increase the amount of air circulation around it to help it recover from the rot.

Bottom rot or crown root rot

If your cactus has minor signs of rotting in the bottom of the stems or the crown root, you can first try to save it by applying fungicides, reducing watering, and moving your plant to an airy, dry spot. If your plant’s stem bottom is otherwise heavily affected, it may be too late to save the entire plant. In such cases, it is recommended to remove the healthy parts of the cactus and propagate them. 

To propagate a rotting cactus, you can follow these steps: 

First, use a clean, sharp knife or scissors to cut healthy segments of the cactus stem or pads. Make sure to leave a clean cut, and avoid crushing or damaging the segments. Let the cuttings dry for a few days, until the cut ends have callused over and are dry to the touch. 

Next, plant the callused end of the cuttings into a well-draining cactus soil mix, or a mix of sand and perlite, and put them in a warm, airy, bright spot away from harsh direct sunlight. Water the cuttings sparingly, only when the soil is completely dry to the touch.

With proper care, the cuttings should start to root and grow into new cactus plants. It is important to monitor the cuttings for any signs of rotting or other issues and to make sure they are not overwatered or exposed to extreme temperatures.

How to prevent rotting

To prevent rotting in cacti, it is important to avoid overwatering and ensure that the soil has good drainage. You can choose a well-draining soil mix that is composed of sand, perlite, and peat moss. It is also important to monitor the plant for signs of damage or stress, such as wilting, yellowing, or brown spots on the leaves. If such symptoms are observed, the plant should be examined carefully for signs of rotting, and appropriate measures are taken to address the problem. These may include reducing the watering frequency, improving drainage, or controlling fungal and bacterial infections.

To prevent rotting in cacti, it is important to avoid overwatering
To prevent rotting in cacti, it is important to avoid overwatering

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