Common Diseases Affecting Aloe Vera Plants and How to Treat Them

Common Aloe Plant Diseases and How to Treat Them

Aloe vera is a succulent plant that is popular for its therapeutic properties and ornamental appeal. However, aloes can fall victim to various diseases that can compromise the health and appearance of the plant. By learning to recognize the signs of disease and taking appropriate preventative and treatment measures, you can help your aloe vera thrive.

1. Soft Rot

Soft rot is one of the most common aloe diseases. It is caused by various bacteria that infect the plant, such as Erwinia, Pseudomonas, and Clostridium. The disease causes the inner fleshy leaves to become discolored and take on a foul odor. Eventually the rot spreads throughout the leaves, causing them to become mushy and melted. Soft rot can rapidly kill aloe vera plants if left unchecked.

To treat soft rot, carefully remove any affected leaves, cutting at least 2 inches (5 cm) below visible signs of rot. Sterilize your pruning shears with rubbing alcohol or a disinfectant between each cut to prevent spreading bacteria. Apply a copper-based fungicide to protect healthy tissue from infection. Improve airflow around the plant and water sparingly to prevent excess moisture leading to bacterial overgrowth.

2. Fungal Leaf Spot

Leaf spots are circular lesions that form on aloe leaves. They are caused by various fungal pathogens, such as Anthracnose, that infect the plant. Spots begin small but can increase in size. As they age, the spots become necrotic with dark borders. Heavily infected leaves turn yellow or brown and may wither.

To manage leaf spot diseases, remove and destroy affected leaves. Be sure to sterilize pruning equipment between cuts. Apply a broad spectrum fungicidal spray to protect healthy leaves from infection. Improve air circulation to reduce surface moisture that encourages fungal growth. Water plants in the morning to allow ample drying time.

3. Black Soft Scale

Soft scales are common aloe pests that extract plant fluids. Black soft scale is particularly problematic, forming black or brown crusty deposits on leaves. Heavy infestations cause yellowing, stunting, and leaf death. Sooty mold may also grow on the sugary excretions (honeydew) of the scales.

Controlling black soft scales starts with pruning off heavily infested leaves. Use an insecticidal soap or neem oil spray every 5-7 days to suffocate juvenile scales. Systemic insecticides that are taken up by the plant, like imidacloprid, are also effective against scale insects. Introduce natural predators like ladybugs or lacewings to keep scale populations in check.

4. Mealybugs

Mealybugs are tiny sap sucking insects that look like bits of cotton. They gather in clusters around aloe plant stems and leaf bases. Mealybugs excrete a sticky honeydew substance that leads to unsightly black sooty mold growth. These pests cause yellowing, distortion, and stunting when abundant.

To control mealybugs, use a cotton swab dipped in rubbing alcohol to remove visible insects. Follow up with insecticidal soap sprays every 5-7 days to kill nymphs that hatch from eggs. Systemic insecticides can help eliminate mealybugs living deeper in plant tissue. Releasing natural predators like lady beetles and green lacewings can provide ongoing control.

5. Aloe Rust

Aloe rust is a fungal disease caused by various Puccinia species. Symptoms appear as powdery orange-brown growths on the undersides of leaves. Rust pustules eventually break open, releasing spores that spread the infection. Leaves become stained and necrotic. Severe infections cause premature leaf drop.

Rust diseases require both chemical and cultural control. Apply fungicides containing azoxystrobin, myclobutanil or triforine every 7-10 days. Improve airflow and reduce overhead watering to keep leaves dry. Remove and destroy severely infected leaves to limit spore production. Periodic applications of horticultural oil can also help suppress rust fungi on aloes.

6. Root Rot

Root rot can have serious consequences for aloe vera. While aloes don’t mind dry soil, excessive moisture promotes root rot fungal diseases. Affected plants deteriorate as the roots are unable to take up water and nutrients. Leaves turn yellow, wilt, and drop off.

Control aloe root rot by improving drainage and only watering when the top few inches of soil become dry. Cut back on watering during cooler months when growth slows. Remove diseased roots and repot plants in fresh, sterilized potting mix. Apply a broad spectrum fungicide drench to protect healthy roots from infection.

7. Crown Rot

Crown rot affects the main stem at soil level. Infected tissue becomes discolored and mushy. As crown rot advances, the entire plant collapses and dies. The fungus Phytophthora is often the culprit behind aloe crown rot.

Prevent crown rot by providing well-draining soil and avoiding overwatering. Improve airflow around the base of the plant. Remove diseased crown tissue and apply a copper fungicide to protect the newly cut stem. Disinfect gardening tools after use on infected plants to avoid spreading the pathogen.

8. Leaf Curl

Aloe leaf curl manifests as upward curling and twisting leaves. The deformity is caused by the phytoplasma pathogen that is transmitted by insects like leafhoppers. Leaf curl causes stunted, deformed growth and yellowing leaves.

Unfortunately leaf curl has no cure, however the disease progression can be slowed. Keep plants vigorous by providing optimal growing conditions. Remove and destroy affected leaves to limit spread. Control insect pests that may transmit the pathogen. Rogue out badly infected plants to prevent contamination of healthy specimens.

Preventing Aloe Diseases

While even the best cared for aloes can develop diseases, implementing preventative practices can help reduce your plants’ risk:

• Choose disease resistant aloe cultivars when possible.
• Inspect new plants closely and quarantine for a few weeks before introducing to your collection.
• Provide well-draining soil and avoid overwatering.
• Disinfect tools after pruning infected plants.
• Improve air circulation around plants.
• Remove dying leaves/stems which can be entry points for disease.
• Control insect pests that may vector pathogens.
• Apply appropriate fungicides/insecticides preventatively.
• Rogue out incurably infected plants to protect healthy ones.

While aloe vera has wonderful healing properties, the plants themselves are prone to diseases. By learning to properly identify and treat issues early, you can keep your aloe houseplants looking their best for years to come.

With prompt care and preventative practices, most aloe vera diseases can be successfully managed. Don't give up on your plants at the first sign of sickness. With persistence and vigilance, you can continue enjoying the beauty and usefulness of aloe vera in your home.

Disclaimer: This article is for informational purposes only and does not constitute medical advice. Always consult with a healthcare professional before starting any new treatment regimen.