Rotting Cactus Treatment – Causes Of Stem Rot On Cactus

By Darcy Larum, Landscape Designer

Recently, cacti and other succulents in fancy little glass terrariums have become a hot ticket item. Even big box stores have jumped on the bandwagon. You can go to almost any Walmart, Home Depot, etc. and purchase a cool little terrarium filled with a mix of live cacti and succulents. The problem with this, however, is they took a really cool idea and then figured out how to cheaply mass produce them. No thought is put into proper drainage of these terrariums or each plant’s specific growing needs.

To ensure that they’ll stick together through shipping and stocking, pebbles or sand are glued into place around the plants. They are basically made to look nice, just long enough for them to be sold. By the time you purchase them, they could have been severely neglected, watered improperly and sitting on death’s doorstep because of Dreschlera fungus or other rot diseases. Continue reading to learn if you can save a rotting cactus.

Causes of Stem Rot on Cactus

Dreschlera fungus is commonly known as cactus stem rot. The first signs and symptoms of Dreschlera cactus stem rot that you may notice are yellow to dark brown or black spots on the cactus. However, these spots are just what you see on the surface. Damage on the inside of the plant could be much more severe.

Stem rot on cactus plants usually begins near the bottom of the plant, then works its way up and throughout the plant. Dreschlera fungus is spread by spores that often infect plant tissues that are already damaged or weakened.

Symptoms can progress to a complete rotting of the bottom of the plant, causing the top to tip over or the center of the plant may sink in upon itself, or the whole plant may suddenly look like a shrunken mummy of a cactus. Cactus stem rot can kill a plant in as little as four days.

Some common factors that contribute to stem rot on cactus plants are over watering or improper drainage, too much shade or humidity and damaged plant tissues from insects, pets, humans, etc.

Rotting Cactus Treatment

Once a cactus plant has rotted so severely that the top has tipped over, has sunken in on itself or looks like a shriveled mummy, it is too late to save it. If it is only showing some small spots of rot, there are a few things you can try to save a rotting cactus plant.

First off, the plant should be removed from other plants, placed in a sort of quarantine and forced into a mock drought. You can simulate drought by placing the plant in sand, not watering it at all and using bright heat lamps. Sometimes, this is enough to kill small patches of Dreschlera fungus.

You can also try to wash away fungal spots with q-tips or a small brush and disinfectant soap. Simply, scrub away the yellow to black fungal spots. Fungal spots can also be cut out, but you will need to cut widely around the spots because healthy looking tissues around the spots may already be infected.

If you choose to try either of these methods, be sure to sanitize your tools, brushes or q-tips in rubbing alcohol or bleach and water between each scrub or cut. Immediately after scrubbing or cutting, spray the whole plant with copper fungicide, the fungicide Captan, or a bleach and water solution.

More Information about General Cactus Care
<<PREVIOUS3 2 1 ... 123NEXT>>
Print This Article
This article was last updated on
Did you find this helpful?
Share it with your friends!

Additional Help & Information

Didn't find the answer to your question? Ask one of our friendly gardening experts.

Do you know anything about gardening? Help answer someone's gardening question.

Read more articles about General Cactus Care.

Search for more information

Use the search box below to find more gardening information on Gardening Know How: