Crassula ovata, commonly known as Jade Plant, is one of the most popular succulent houseplants. There are many varieties from which to choose, each of which has similar cultivation needs. Jade Plant problems that cause black spots range from insects, viruses, fungal disease and even incorrect care. Native to South Africa, Jade Plant has low moisture needs and can become seriously damaged in poorly draining containers and planting media. Sucking insects and various diseases can also take a toll on foliar health and appearance.
It is important to investigate possible causes for black spots on Jade Plant leaves. Proper diagnosis can lead to correction of the issue and the return of your plant's health.
Insect pests of Jade Plants include mealy bugs, spider mites and aphids. Mealy bugs appear as tiny balls of white cotton. Removal with cotton swabs dipped in alcohol is the recommended treatment. Spider mites are tiny black insects thriving on dusty plants and feeding on the undersides of leaves, causing the Jade Plant to look speckled. Control of spider mites involves wiping Jade Plant leaves with water or alcohol. Aphids are sucking insects that feed in colonies. Color of aphids range from green to yellow, brown or black. Honeydew excreted by aphids provides a growing medium for sooty mold, causing black discoloration on Jade Plant leaves. Wash infected leaves to remove aphids as soon as they are discovered. Insecticidal soaps should not be used on Jade Plants.
Black spots on Jade Plant leaves can be caused by viruses. Black ring is a virus that appears as black spots on the undersides of leaves. Tomato-spotted wilt virus, a topsovirus, also creates dark or black spots on leaves of infected plants. Although viruses do not kill Jade Plants, viruses can be systemic, so infected plants should not be used for propagation. Spread by insects, viruses are controlled best through prevention of insect infestation.
Fungal disease can cause black spots on Jade Plant leaves. Due to their succulent tissues, Jade Plants are less troubled by fungal disease than many other types of plants. However, anthracnose and other fungal diseases can disfigure Jade Plants when humid conditions prevail. Pruning plants with infected tools contributes to the spread of fungal disease. Wipe pruning equipment with alcohol or other disinfectant to prevent spread of disease.
Jade Plants require good drainage. Planted in sandy soil in clay pots, Jade Plants need water only when dry. Too much water causes root rot or edema. Root rot results in dropping leaves and death of the plant. Edema, swollen cells resembling blisters, begins on lower, older leaves. Blisters become discolored and turn corky. Often, affected leaves fall off the plant.
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