Succulents thrive well in places with a dry climate. They can survive for days and weeks without water since their leaves and stems retain water, helping them to survive hot temperatures. However, during cold weather, the plants become prone to fungal diseases. In this article, let us get to know the common fungal infections among succulents as well as treatment measures.
Common Types of Fungus on Succulents
1. Sooty mold
Scientific name: Capnodium citri
Sooty mold is also called black mold, and is considered the least damaging among the fungal infections. It is caused by pests like mealybugs, whiteflies, scales, and aphids. These pests excrete honeydew, a sweet substance which the mold feeds upon. To eradicate the sooty mold you should also remove the pests.
Sooty mold is less damaging than other fungi, but it can alter the photosynthesis process, especially if the colonies are massive.
2. Grey Mold
Scientific name: Botrytis cinerea
Grey mold spreads easily during cold and wet weather, and especially during early spring and summer. It forms grayish-brown spore masses on the surfaces of succulent leaves. This fungus prefers decayed or damaged plant tissues and spreads easily. You have to cut off the affected plant areas and burn the damaged tissues to avoid the spread of infection.
3. Fusarium Wilt
Scientific name: Fusarium oxysporum
This fungus causes heavy stress, yellowing, wilting, and death among succulents. It prevents the plants from taking up water. It enters the plant through the roots and multiplies in the vascular tissues. The tissues become blocked, so the plant is unable to absorb enough water for nourishment. You will notice brown streaks if you cut the leaves of infected plants.
To prevent this fungus from penetrating your plants, see to it that your gardening tools are well-sanitized. Affected plants that are still at the early stages of infection should be sustained with enough water and feeding to help them survive and grow new tissues. Avoid overwatering so there won’t be further fungal growth.
Scientific name: Colletotrichum spp.
This fungus affects many succulents and cacti and is characterized by moist, tan-colored rot with orange, red, or pink pustules on the surface. The spots spread quickly on crowns and leaves, so you need to remove the affected parts to avoid the spread of infection.
The infection spreads easily through contaminated soil and pots. Avoid reusing the soil and make sure that your tools are clean and sanitized.
5. Leaf spots
This fungal infection is caused by the leaf spotting genera of fungi that include the following:
This type of fungal infection is usually harmless, but it can disfigure succulents. You may notice shallow tan lesions and spotting in the leaves, although most plants can tolerate the spots. However, while the infection may not cause damage, it can be transferred and could affect other plants.
6. Root and crown rot
This fungal disease is caused by soil-borne fungi such as the following:
- Phytophthora spp
- Pythium spp
- Rhizoctonia solani
- Fusarium spp
Root and crown rot can lead to the deterioration of a succulent’s root system and lower branches near the soil line. It is a chronic infection that can lead to the death of plants. The symptoms during the early stages are not specific, which makes it difficult to differentiate this disease from other infections.
The affected plants become wilted, stressed, and change colors. They eventually die from a slow rot that starts from the soil level. Some ways to protect your plants from this disease include planting succulents in fast-draining soil and avoiding overwatering them.
Treatment Methods for Fungus on Succulents
These are some of the most common treatment methods for fungus on succulents:
Through the use of fungicides
Using fungicides such as copper methyl thiophanate, dicyclidine, or benomyl is an effective treatment for fungus on succulents. However, these chemicals can only stop the spread of the infection and protect other plants from being affected.
The damaged plant areas cannot be restored anymore. You need to properly identify the type of fungal infection so it can be treated with the right fungicide.
Copper fungicides control and treat various infections like black spots, powdery mildew, and bacterial leaf spots. To prepare, mix one half to two ounces of copper fungicide with one gallon of water.
You need to identify what infection you are dealing with since some types of fungal infections do not need fungicides. Spray the fungicide liberally, repeating the procedure every seven to ten days until there are no visible traces of the disease.
Recommended fungicides include Bonide Neem Oil, Pure Crop 1, and Regalia Biofungicide.
Here are some tips when purchasing fungicides:
- Be sure to diagnose the disease correctly.
- Read the label to ensure if the product is safe to use in the home environment and around humans and animals.
- Take special notice of the mixing instructions.
- Through the use of homemade or DIY fungicides
These are eco-friendly and cost-effective DIY fungicides to treat fungus on succulents:
- Baking soda – Simply mix four teaspoons or one heaping tablespoon of baking soda in one gallon of water.
- Dishwashing soap – Dilute it with water before applying it to affected areas. Make sure that it does not have harmful ingredients like bleach.
- Pyrethrum – Chrysanthemums are also used as a fungicide. You need to dry the flower heads and grind or soak them overnight in ⅛ cup of alcohol. Mix it with four gallons of water and strain it through a cheesecloth.
- Bordeaux mixture – It is also called a Bordo mix and consists of a mixture of copper sulfate and quicklime. Simply mix four parts of copper sulfate and four parts of quicklime with 50 gallons of water. This fungicide may be toxic in the long run so you need to reduce the doses gradually to prevent the copper from leaching into the soil.
Succulents are prone to fungal diseases, especially during cold, wet weather in the early spring and summer. Common fungus on succulents includes the fusarium wilt, sooty mold, and grey mold.
Commercial fungicides are effective treatment measures, but you can also prepare homemade fungicides through the use of baking soda or dishwashing soap.
Image: istockphoto.com / soniabonet