With over 180 species of aloe, aloe vera (Aloe barbadensis) grows in many homes as a houseplant or commercially in tropical and subtropical areas. Although it originated in Africa, its history stretches back 6,000 years as many cultures used it for a variety of maladies, now especially as treatments for sunburns and cuts. Like most plants, though, aloe is subject to diseases and pests, which sometimes cause brown spots to form on its leaves.
Aloe vera, which is a succulent, produces a cluster of fleshy leaves lined with short spines. In desert areas, aloe bears flowers in the spring. The leaves cluster around a centre spike and grow up to 10 inches long with patches of light green or grey speckles. These flowers look tubular in shape and form on top of long stems, which can grow up to 3 feet tall.
Aloe vera makes its home in dry, desert conditions, thriving any place where temperatures do not freeze. It is sun loving and needs bright light when grown as a houseplant; just make certain to keep it out of direct sun. According to the University of Arizona Extension, you should water aloe vera deeply during the summer but let the soil dry out between watering times, as overwatering will cause the roots to rot.
Either bacteria or fungi cause leaf and rust spots to form on an infected aloe plant. These dark spots appear where water has stood on the leaf, causing it to rot. Rust and leaf spot rarely kills an aloe plant but instead renders it unsightly.
Having a weakened or unhealthy plant ups the chances that it will contract a fungus or bacteria that will cause problems for your aloe. When watering, make certain to water the base of the plant instead of the leaves. To keep your plant healthy, make sure it has plenty of bright light, good circulation and proper drainage.
Setting an aloe vera plant too long in the sun can cause it to become sunburned and display either orange or dark brown spots. These spots differ from the wet-looking ones caused by fungus or bacteria in that they appear as stiff, woodlike spots. When an aloe plant becomes sunburned, the internal tissue dries up and brown spots appear on the outside of the leaves. Bright but not direct sunlight creates sufficient lighting for an indoor aloe plant. If sunburn spots appear, move the plant to a shadier place.