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Cacti are hardy and resilient plants, but they can still fall victim to various diseases that threaten their health and appearance. Recognizing these diseases early and understanding how to treat them is essential for every cactus enthusiast. In this article, we explore the top 10 cactus diseases and provide effective solutions to cure them.
1. Root Rot
Root rot is a common and serious disease caused by overwatering and poorly draining soil. It leads to decayed roots, which can cause the plant to wilt and die if untreated.
Signs: Soft, black, or brown roots; wilting; foul smell from the soil.
How to Cure: Remove the cactus from the soil, cut away affected roots with sterilized tools, and let the plant dry for a few days. Repot in well-draining soil and water sparingly.
2. Mealybug Infestation
Mealybugs are small, white, cotton-like pests that suck sap from cacti, weakening the plant and causing deformities.
Signs: White cottony masses on plant surface, yellowing, stunted growth.
How to Cure: Remove pests manually with a cotton swab dipped in alcohol. Apply insecticidal soap or neem oil regularly until infestation subsides.
3. Scale Insects
Scale insects appear as small, round, shell-like bumps on the cactus surface. They feed on plant sap and can cause severe damage.
Signs: Bumps on the cactus, sticky honeydew, yellowing leaves.
How to Cure: Scrape off scales with a soft brush or cloth. Use horticultural oil or insecticidal soap to eliminate remaining pests.
4. Fungal Diseases
Fungal infections can cause spots, mold, and decay on cacti. They often result from excess moisture and poor airflow.
Signs: Discolored spots, fuzzy mold, soft decay areas.
How to Cure: Remove affected tissue, improve ventilation, and reduce watering. Apply fungicides if necessary.
5. Bacterial Soft Rot
Bacterial soft rot causes parts of the cactus to become mushy and foul-smelling. It spreads rapidly if not addressed promptly.
Signs: Soft, water-soaked areas, foul odor, black or brown decay.
How to Cure: Remove and discard infected parts. Sterilize tools and treat the plant with a bactericide. Improve drainage and avoid overwatering.
6. Spider Mites
Spider mites are tiny pests that spin fine webs on cacti. They feed on plant sap, causing stippling and discoloration.
Signs: Fine webbing, speckled or yellowed tissue, leaf drop.
How to Cure: Spray with neem oil or insecticidal soap. Increase humidity and wash webs off with water.
7. Rust
Rust appears as orange or reddish pustules on cactus surfaces, caused by fungal or bacterial pathogens.
Signs: Colorful pustules, tissue damage, spots spreading over time.
How to Cure: Remove affected tissue, apply a fungicide, and improve air circulation.
8. Viral Diseases
Viral infections in cacti can cause mottling, deformities, and stunted growth. They are often spread by pests or contaminated tools.
Signs: Mottled or streaked appearance, abnormal growth patterns.
How to Cure: Remove and destroy infected plants. Prevent pest transmission and sanitize tools. There is no cure for viruses once infected.
9. Anthracnose
Anthracnose is a fungal disease that causes dark, sunken lesions on cactus surfaces, leading to tissue death.
Signs: Dark spots with concentric rings, sunken areas, spreading lesions.
How to Cure: Remove infected tissue, apply fungicides, and avoid overhead watering.
10. Sunburn
Sunburn occurs when cacti are exposed to intense sunlight without acclimation, causing tissue damage and discoloration.
Signs: White or brown scorched patches, peeling skin.
How to Cure: Move the cactus to a shaded area temporarily, gradually increase sun exposure, and ensure proper watering.