Diseases of Succulents

Rhizoctonia Rot

• If a succulent turns transparent, rhizoctonia rot is the likely culprit. This fungal disease begins in the stem and produces whitish-gray threads on the soil. Follow the general procedure and get rid of the diseased plant and any others affected. Place the other plants in new, uncontaminated soil after a fungicide soak in benomyl or captan fungicides, or one containing 8-hydroxyquinoline sulphate.

Helminthosportium Stem Rot

• Helminthosportium stem rot thrives during low temperatures and high humidity. It appears as a soft, green coating over the plant and causes young succulents to quickly wither. Remove any affected plants, treat healthy surrounding plants with a fungicide containing captan and place them in new soil.

Epiphyllum Mosaic Disease

• Plants that turn pale yellow, develop sunken lesions at the edges of leaves and have difficulty flowering may be infected with epiphyllum mosaic disease. It often affects Schlumbergera and Rhipsalidopsis cacti and Zygocactus. Remove affected plants from the soil and destroy them; soak other nearby succulents in benomyl to prevent the spread of disease.

Anthracnose

• Anthracnose is identified by round, dry, sunken spots that may be brownish or light-colored. The succulent may have a bark-like consistency in places. Cut back any infected tissue from plants, disinfecting the knife after each cut to see if the plant improves. Apply triforine, maneb powder spray, captan or mancozeb.

Fusarium Rot and Wilt

• Fusarium rot and wilt is caused by a fungus that attacks the neck of the root, turning it brown and then wilting the shoots as it moves through the plant. If you see reddish-brown discoloration after cutting open a shoot or reddish or violet spores on a succulent, it is likely fusarium rot. Remove plants that are infected and apply benomyl spray to the rest. Keep the temperature and humidity low to prevent fusarium rot and wilt from returning.

Wet Rot

• Pythium and Phytophthora cactorum cause wet rot, which attacks the base of the stem, turning it pulpy and rotten. Remove and destroy any infected plants and pots, and apply a fungicide containing prothiocarb or fenamiphos to remaining succulents that could be infected. Avoid watering plants in cool weather.