Why Does My Rubber Plant Have Spots On Leaves?

Are the spots brown?

Has the temperature dropped below 40 °F recently?

Are there any large, brown, ringed circles on the tips of leaves or near the leaf shaft?

Are there any tiny, water-soaked dots that grow into irregularly shaped, brown lesions?

Are the spots yellow but turning brown as they age?

Are the spots black and powdery, leaves are sticky from honeydew?

Are the spots white and powdery?

Temperatures below 40 °F can injure a rubber tree. For outdoor container plants, covering the tree with a blanket if it gets below 40 °F for a night will offer some protection. Indoor plants should be placed away from air conditioning vents. If the rubber tree is exposed to cold temperatures, large brown spots will form on leaves, and new leaves may wrinkle and turn brown. Unless the cold was severe enough to kill the roots of the tree, eventually it will recover.

Botrytis blight is a fungal disease that affects plants in cool, wet conditions. The blight appears as large, brown, ringed circles on the tips of leaves or near the leaf shaft. Remove affected leaves when you see them, and clean any plant debris from around the base of the tree. Water the soil at the base of the plant to keep water off of leaves. Water the rubber tree when the top inch of soil dries and be sure to use a pot with drainage holes for container plants. Avoid overwatering.

Water-soaked spots on rubber plants leaves are caused by bacterial blight. The copper spray will help in reducing the spread of the disease. Remove all leaves with brown spots from plants, and also remove any dropped leaves to help break the life cycle of this disease.

A potassium deficiency can cause yellow-brown dead spots along the edges of lower leaves. Rubber trees planted in heavily alkaline soil are more susceptible to potassium deficiency. Feed rubber trees once a month during the active growing period with a 3:1:2 or similar rate fertilizer diluted to one-half strength. For example, if the fertilizer calls for 1 tablespoon dissolved in 1 gallon of water and poured into the soil, use 1/2 tablespoon dissolved in 1 gallon of water.

Anthracnose is a fungal disease that causes yellow spots on leaves. The yellow spots turn brown as they age. Frequent misting can bring on the disease for indoor plants. Avoid overhead watering to keep water off the leaves, and follow a regular watering schedule to keep the soil from becoming too wet. You can also spray leaves with a copper fungicide when you notice the spots to help prevent spread.

Black spots or patches on the leaves are caused by a fungal disease Sooty mold. This fungus grows on honeydew produced by aphids, whiteflies, and scales. The black coating doesn't harm the leaves directly but it does reduce the intensity of photosynthesis. Sooty mold is best controlled by dealing with the insects that are producing honeydew. Remove honeydew and sooty mold from the leaves by wiping it with the damp cloth.

White, powdery spots, or patches on the leaves are caused by a fungal disease Powdery mildew. Powdery mildew usually appears in damp places. Encourage good air circulation around the affected plants by thining them and any surrounding plants. Water plants from bellow to keep foliage dry. Any affected leaves should be cut off and removed. Any commercial fungicidal spray will protect your plant from further infections.

Rubber plants suffer from sunburn when they're suddenly exposed to too much light. This can happen when plants that are used to low light are moved to a brighter spot. Symptoms include the appearance of yellow or white spots and patches on the leaves. The spots may turn brown as the tissue dies, and the leaves may fall off the plants. Acclimate your rubber plant to bright light in stages, gradually moving them into brighter and brighter locations until they're placed in their final spot.