Kalanchoe Leaf Problems

The kalanchoe is a succulent, flowering plant from Madagascar, which the German hybridizer Robert Blossfeld introduced to the Western World in 1932. The plant, which people commonly use as a decorative houseplant, produces clusters of four-petaled flowers that bloom white, yellow, orange, pink, magenta or red, as well as thick, dark green, waxy leaves with scalloped edges. Unfortunately, the leaves of kalanchoe plants are susceptible to several problems that can cause the plants to suffer aesthetically.

Black spot is a fungal disease that causes dark-colored blotches to appear on kalanchoe leaves. In addition to causing aesthetic damage, black spot can damage leaves at the cellular level and even cause them to fall off: a phenomenon that is known as defoliation. To treat kalanchoe plants with black spot, pick off the infected leaves and provide the plants with more sunlight.

In some instances, it's hard to detect the existence of powdery mildew on kalanchoe leaves, as the mildew may only produce a fine, white webbing. However, other symptoms of powdery mildew can include mottling, yellow spotting, ring or line patterns and flecks. As powdery mildew progresses, a dusty, grayish-white coating may appear on kalanchoe leaves. Like black spot, powdery mildew is a fungi-based problem. However, powdery mildew consists of minute hyphae, or branching filaments, as opposed to spores. Treat kalanchoe plants with powdery mildew by rubbing them clean and by applying a potassium bicarbonate mixture.

An infestation of mealybugs can cause the leaves of kalanchoe plants to turn yellow and droop. In addition, the appearance of mealybug egg sacks and excrement on kalanchoe leaves can be aesthetically displeasing. Mealybugs are small, slow-moving insects covered with a powdery wax. The insects feed on the sap of kalanchoe plants and commonly accumulate underneath plant foliage, where they are hard to see. Treat kalanchoe plants with mealybugs by applying pesticides or by wiping down leaves with alcohol.

Like mealybugs, aphids are small insects that feed on the sap of kalanchoe plants. While small populations of aphids do not usually cause significant damage, large populations can cause kalanchoe leaves to yellow, curl and otherwise distort. The honeydew that aphids release on leaves may encourage the growth of fungal infections. To remove aphids from kalanchoe leaves, pick the insects off or treat the leaves with a narrow-range oil, neem oil or insecticidal soap.

Browns scales are another variety of sap-sucking insect that can invade kalanchoe plants. While brown scales in the nymph stage have functioning legs, older brown scales remain permanently attached to leaves, appearing as broad, brown, scale-like features. In addition to being visually displeasing, brown scales can cause kalanchoe leaves to yellow and decline in health. Remove brown scales by scraping them off of leaves.