If you've noticed any strange spots or discoloration on your succulents, you're not alone. It's crucial to learn how to identify various types of molds or spots - such as black, brown, white, or grey - and treat them. Identifying molds on succulents can be a challenge, but with the right knowledge and tools, you can take action to treat and prevent them. This guide will teach you to identify them, explain the causes of mold growth on succulents, and offer solutions to help you keep your plants healthy and mold-free. Let's get started!
Black spots/marks on succulents
01 Sunburn mark
Although succulents prefer enough sun exposure to thrive in color, too much can cause sunburn marks on their leaves, especially for outdoor or grounded plants. If the temperature stays above 90 degrees for a while, it's a good idea to provide a sunshade to prevent further damage. If the leaves turn pale and white, the sunburn is mild, but if they develop brown or black marks, the damage is irreversible, and new leaves will need to grow. That's why taking preventative measures is so important to avoid sunburn damage.
02 Anthracnose: black molds caused by C. gloeosporioides
Succulent anthrax is caused by infection with anthrax bacteria (C. gloeosporioides). The anthrax is most easily detected during the rainy summer months, particularly when the weather conditions are characterized by high temperatures and humidity. In environments with high humidity and insufficient ventilation, pathogens can generate conidia, which is the primary cause of infection. Anthracnose is a highly contagious disease that initially appears as one or more conspicuous black spots on the tender leaves. These spots are soft to the touch and can spread quickly if not managed effectively.
If left untreated, anthracnose can rapidly spread and infect adjacent succulents, leading to the shedding of a significant number of leaves even upon slight touches. Immediate action is crucial to prevent the propagation of black rot. If you notice any signs of anthrax on your succulents, it's important to take immediate action to prevent it from spreading to other healthy succulent plants.
Firstly, separate the infected succulent from the others, and locate it in airy location without direct sunlight. Then, dilute benzopyrazole with water at a ratio of 1:1000 or 1:1500 and spray it onto the infected succulent every 2-3 days. Continue spraying the infected area for two weeks, until the area scabs and the infected leaves fall off, and there are no new leaves infected. And please remember do not give other water during this period. If you don't have benzopyrazole, you can also use mancozeb and follow the same steps. It's important to monitor the other succulents for any black spots, which may indicate an infection. Plus, growing succulents in airy location is very important. By taking these steps, you can potentially save your succulent and prevent further damage.
03 Sooty Mold/Black Mold
Succulents suffer from sooty mold disease, which is manifested by a thick layer of black mold spots attached to the front or back of the leaves. Particularly the center of the rosette will quickly turn black and shrink, and soon mold spots will appear on the stems, followed by a large number of leaves wilting and falling off, leading the plant to die. In some cases, scale insects would appear together with sooty mold. It is imperative to bear in mind that sooty disease is contagious, and therefore, prompt action is necessary upon the identification of any signs of this disease.
Succulent plants can be susceptible to sooty disease due to two primary factors. Inadequate ventilation during high temperatures and humidity, which typically occurs during the summer and rainy seasons, is the first factor. The second factor is caused by insect pests that feed on the plant, such as mites, aphids, flies, and bugs. Sooty mold is a dual infection of parasitic fungi and epiphytic molds. To prevent and treat it, a combination of sterilization and insecticide is necessary. It is also essential to control the environmental humidity and maintain good ventilation and sufficient light.
If your succulents have been affected by sooty disease, it is important to take prompt action to remove any mold buildup. You can carefully clean the affected areas by using a cotton swab dipped in water. However, some spots may be difficult to remove and may have already caused damage to the succulent cells. To disinfect and clean the affected areas, use 75% alcohol. Then, dilute mancozeb or difenoconazole with water at a ratio of 1:1000 or 1:1500, following the instructions. Soak the infected plants by using the bottom watering method once every two or three days for three weeks. This will make the mold disappear, and your succulents will recover. Remember not to give the succulents any additional water during the treatment.
You may wonder know: what is bottom watering succulents?
Brown spots/marks on succulents
01 Rust disease/Rust spots
Have you noticed rusty patches on the leaves of your succulent plants? These patches usually appear as orange or tan spots that resemble iron rust. When the succulent rust disease is severe, the leaves may even look like the skin is chapped, which looks very scary. While some people may think that a lack of water is the culprit, rust disease is actually caused by fungal infections that thrive in humid environments. If you have succulent plants like Echeveria Suyon, Echeveria Melaco, x Sedeveria 'Letizia', Echeveria 'Hakuhou', or some Echeveria agavoides succulents, they may be particularly susceptible to rust disease. Fortunately, with the right knowledge and tools, you can take action to treat and prevent them.
To deal with rust disease, start by removing infected succulents from their original planter and washing the leaves, stems, and roots with clean water. Trim any excess hair roots with scissors. Dilute mancozeb powder with water at a ratio of 1:1000 and soak the succulent in the solution for 2-3 minutes. Afterward, let the plant dry for 2-3 days in a well-ventilated area. Once the wound has healed, replant the succulent in fresh soil. To help with recovery, continue to spray the diluted solution onto the infected areas of the plant twice a week for 2-3 weeks. Slightly infected leaves will gradually recover, while seriously affected leaves may fall off. With the right care and attention, your succulents can thrive and continue to add natural beauty to your space.
Sometimes sunburn can also be brown, as shown in the picture. The method of prevention is the same as before.
03 Brown spots on the leaves
If one observes the presence of brown spots on succulent plants, it may be attributed to a fungal infection or overwatering while under direct sunlight. In order to address this issue, it is recommended to combine carbendazim powder with water at a 1:1000 ratio and pray the solution to the leaves every 2 days for two weeks. It is imperative to avoid watering the succulent while it is under direct sunlight and to ensure that there is no accumulation of water on the leaves. The optimal times to water your succulents are in the morning or after sunset during hot summers. Adequate ventilation is essential when growing succulents indoors.
01 Powdery mildew on succulents
If you're growing succulents indoors, it's important to keep an eye out for powdery mildew. This pesky problem can be caused by watering habits and the planting environment. While some growers prefer to water their succulents at night, it's important to note that this can increase the risk of powdery mildew if there is poor indoor ventilation and high humidity. It's generally not recommended to water succulents at night, except during the summer months. To prevent powdery mildew, it's important to keep your environment well-ventilated and to water your succulents during the day.
Avoid watering the leaves or spraying water on them like you would with other indoor houseplants. To sum up, pay attention to factors like ventilation, soil, and moisture. Use soil with good drainage properties and make sure the planter pot has bottom holes to improve drainage.
To keep your succulents healthy, it's essential to take action if you notice powdery mildew. First, isolate the infected plants to prevent the spread of the disease. For mild cases, you can moisten the affected succulent leaves with a 75% alcohol solution. Make sure the soil has proper drainage, and repeat this process 2-3 times a week for two weeks to see improvement.
To address severe powdery mildew, you may dilute benzopyrazole powder with water at a ratio of 1:1000 or 1:1500. It's also important to ensure good ventilation for the succulent's growth. You can apply the mixture by spraying it 2-3 times a week for a week. Instead of spraying the solution onto the leaf's surface, bottom watering may be more efficient to deal with this fungal infection.
If you notice white fluff on your succulent, it could be the natural farina on the plant, or mealybugs if it looks like white bugs or insect eggs. Mealybugs usually hide between the stems and leaves of the succulent, and they can quickly spread to other plants. To avoid further damage, it is essential to treat the infestation promptly.
If you decide to use homemade organic fertilizers, keep in mind that they may attract pests like mealybugs due to their strong odors. This can cause infestations as the bugs lay eggs and reproduce rapidly. Additionally, environments that are hot and humid can also contribute to scale insect infestations.
If you encounter mealybugs, it's important to thoroughly clean the entire plant with clean water, paying special attention to the stems and roots. After cleaning, you can then spray the plant with 75% alcohol several times or use neem oil for treatment. If the mealybug infestation is not severe, you can replant the treated succulents at this point. However, in more serious cases, you may need to use an Imidacloprid solution to treat the mealybugs according to the instructions provided.
You may wonder know: How to use neem oil to deal with mealybugs on succulents.
03 Cochineal on leaves
Did you know that cochineal insects have both male and female categories? The males are very active and can fly thanks to their wings, while the females stay put on the cactus. Interestingly, the female bugs produce carminic acid, which is a natural coloring agent used in food and cosmetic products.
Cochineal insects mostly occur on cactus plants and are mostly cultivated artificially for business. If you notice cochineal insects on your cactus plants, don't worry. You can cut off the part where the cochineal insects are growing. As stem-cutting propagation is an efficient way to propagate cacti, don't worry this solution will destroy the growth of the cactus. In more severe cases, carbamate can be used to treat the problem. However, it's important to follow the medication instructions closely to avoid causing damage to the entire plant through overuse.
Green spots on succulent leaves
01 Green raise spots/Ellen spots
Green raised spots are mainly caused by exposure to rain for a long time. Because these green raised spots often occur on Graptopetalum sp (‘Ellen’), some people also call this spot Ellen’s spot. If this happens, don’t panic, just move the succulent to a dry and ventilated environment. If you can't tell the difference between Ellen's spot and anthracnose infection, you can try treating it with a carbendazim solution. Even if it is Ellen's spot, spraying a diluted solution of carbendazim will not affect the normal growth of succulents.
02 Coloration spots/bloody spots
Coloration spots are a condition in which, under extreme circumstances, some succulent cells in the leaves rupture, and anthocyanins stain the leaves locally. Generally, when the temperature drops suddenly in winter and there is good sunlight during the day, the frostbitten leaf cells are partially destroyed, and the anthocyanins produced after rapid repair dye the leaves red.
Many Echeveria elegant succulents can easily form blood spots.It may be worth your while to explore Echeveria x gilva 'Gilva', Echeveria lala, Echeveria Blood Warbler, and Echeveria The Next Gardener Bloody Peach. These plants are known to develop blood spots, which serve to enhance their appeal. With appropriate exposure to sunlight, their colors become more vibrant. As temperatures decline, the entire plant may turn red, and the edges of the leaves will become translucent, resembling jelly. Additionally, the leaves will be adorned with blood spots, creating a breathtaking visual display.
It is common for succulents to develop spots or marks due to infections caused by high temperatures and humidity, especially in summer. To keep your succulents healthy, it's important to monitor them for any unusual spots and take prompt action. Delaying treatment can result in the loss of many succulents. However, appropriate solutions can save your succulents and also help you learn more about gardening. When treating infected succulents, remember to treat all succulents nearby the infected one to reduce the risk of spreading. Plus, prevention is always better than treatment. Improving ventilation all year round can prevent infections.
Most fungal infections are covered by the tips mentioned above. If you encounter an unfamiliar fungal infection, you can send us a picture, and we'll do our best to provide a solution. If you find this blog helpful, please save it and share it with your fellow succulent enthusiasts.