Even if your favorite cactus is a prickly little guy that you shower with love, it’s not totally invincible. These exotic survival experts can still fall victim to infections and viruses. I’m here to walk you through the best ways to handle these issues so your green friend can get back to its healthy self in no time!
Fungal Infections: The Most Common Culprit
In the plant world, fungal infections are pretty widespread across all kinds of species. Unfortunately, cacti and their sensitive root systems aren’t immune. The good news? If you catch the infection early, you can usually save your succulent and stop the spread. Here’s a breakdown of the three most common fungal issues and how to treat them:
Anthracnose (Gloeosporium)
- What to look for: Sunken, round brown spots that feel hard and corky.
- How to treat it: Carefully cut out the damaged areas. Dust the fresh cuts with sifted charcoal powder and then spray the plant with a specialized fungicide like “Saprol Pilz-frei.”
- Pro Tip: To play it safe, treat your neighboring cacti too—prevention is key!
Fusarium Wilt (Fusarium verticillioides)
- What to look for: Dark brown discoloration at the tips, a reddish-purple spore coating on the skin, and visible wilting as it gets worse.
- How to treat it: Isolate the cactus from your other plants immediately. Repot it and spray both the roots and the body with a “Chinosol” (8-hydroxyquinoline) solution.
- Pro Tip: Always “bake” your cactus soil in the oven to disinfect it before planting to kill off any lingering spores.
Root and Stem Rot (Phytophthora)
- What to look for: A soft, mushy, brownish body. The discoloration usually starts at the base, and in advanced cases, the roots will be completely rotted.
- How to treat it: Cut off the healthy top part of the plant and let it root as a head cutting in loose, mineral-rich substrate.
- Pro Tip: You can prevent rot by keeping your cactus dry during its winter dormancy and being careful not to overwater during the summer.
Dealing with Viral Diseases
Cacti can also catch viruses. Common signs include stunted growth, weirdly shaped stems, or the plant just failing to thrive. These viruses are usually spread by insect bites or—more commonly—by using dirty pruning tools. Unfortunately, there’s currently no known cure for viral infections in cacti.
If you suspect a virus, you need to quarantine the plant immediately to protect the rest of your collection. If the diagnosis is confirmed, the cactus sadly has to go in the trash. To prevent viruses from spreading in the first place, always use clean tools and disinfect your shears with rubbing alcohol between every cut.
