The common name "white mold" typically refers to Sclerotinia stem rot, which mainly affects field crops. If you have white mold on your succulent, you are more likely dealing with powdery mildew, a common houseplant ailment that is easy to treat. It can live on both stems and fleshy leaves of succulents.
Powdery Mildew
Powdery mildew prefers the same type of habitat as succulents: warm, relatively dry areas. Because succulents and powdery mildew thrive in similar living conditions, succulents are the most susceptible type of plant. The infection may present as the classic white, powdery coating. However, it can also have a gray appearance with round, yellow, brown, or black growths. The powdery mildew can appear in just one spot, but more commonly, it spreads to other leaves, stems, and buds of the plant.
Effects
At first, powdery mildew may seem harmless. Your succulent may be able to live with the white, moldy-looking disease and even thrive for some time. However, as the infection progresses, you may notice deflated, damaged, or deformed leaves. The leaves and stems may also turn pale green and then yellow. If your plant has a severe infection, it may lose leaves, fail to flower, or even die. Once one of your plants has powdery mildew, the disease can spread to others.
Treatment
To treat powdery mildew, gently remove any infected leaves and stems that show signs of damage, and apply a fungicide. The fungicides containing sulfur, neem oil, or triforine may kill powdery mildew on healthy leaves, stems, and buds. Also, use the fungicide on nearby plants as a preventative measure. Some gardeners have reported success with baking soda mixed with horticultural oil.
Prevention
If possible, separate your infected plants from your healthy plants. Next, work to increase air circulation to help slow spore production. Do this by selectively pruning plants, moving them to windier locations, or using fans to circulate more air in your home. Spores need some humidity, so switching to early-morning watering can help slow or prevent the spread of powdery mildew.
Source: sfgate.com
Links
- Succupedia: Browse succulents by Scientific Name, Common Name, Genus, Family, USDA Hardiness Zone, Origin, or cacti by Genus