One of the few landscape trees that grow almost effortlessly indoors is Schefflera, also called umbrella tree. Schefflera's open, delicate growth habit and dark green, glossy foliage brings a tropical feeling to any home. Schefflera can grow to 8 feet tall indoors and demands little more than regular feeding and watering with an extra smidgen of humidity. Indoors, schefflera rarely suffers from diseases, though some rots or molds may develop under certain conditions. If the plant summers outdoors, it may be more susceptible to bacterial or fungal diseases.
Alternaria and Phytopthora fungi cause similar symptoms, including leaf spots and leaf drop. Some Alternaria fungi cause damping-off, which is lethal to seedlings. If the plant is outdoors in rainy weather, keep it away from any garden plants already infected with fungal diseases, since the spores can travel both by splashing water and on the wind. Do not over-water scheffleras. If the plant becomes infected, cut away as much diseased material as possible and dispose of it away from the plant. If the schefflera is severely infected, you may still save it. Take it out of its container, rinse off the growing medium and apply fungicide formulated with iprodione or mancozeb. Follow manufacturer's directions. Discard the growing medium and sanitize the container before repotting the plant.
Indoors or out, schefflera may be a target for spider mites or aphids, especially in warm, dry weather. These tiny insects not only suck the juices from the foliage, they leave behind a sticky substance called honeydew. Honeydew attracts ants, and it also serves as a growing medium for sooty mold, also called black mold. Wash the tops and undersides of the leaves to get the insects and honeydew off the plant. Use horticultural oil, following label directions, to control severe infestations. Repeat regularly to keep the schefflera free of insects and their leavings.
Dwarf Scheffleras may contract Pseudomonas leaf blight, which causes leaf drop and blighted areas that look waterlogged. Cut away infected areas and keep the plant's foliage dry. Xanthomonas leaf spot on both standard sized and dwarf cultivars causes scattered, beige spots that may eventually merge to form blotches between the still-green leaf veins. Prune out infected areas and increase the amount of fertilizer to help the plant fight off disease. Check English ivy growing nearby to see if it is the source of Xanthomonas leaf spot spores.
Chlorosis occurs when the schefflera's foliage turns yellow. This problem can mimic the symptoms of diseases but is generally caused by low light exposure. Increase the amount of light the plant gets and keep it away from indoor heating or air conditioning vents. Poor drainage or over-watering can cause root rot, which can kill scheffleras. The base of the plant or the roots may turn soft, dark and watery-looking. Transplant the schefflera to a container that has better built-in drainage and switch to a growing medium that has better natural drainage.