Brown Spots on a Potted Shrub

Anthracnose

• Anthracnose is a common leaf spot disease that also causes the shrub’s foliage to wilt and fall off. This fungal disease develops on dead foliage and debris that lies around, or in, the shrub’s container. The infectious fungal spores are transported onto the shrub by wind and rain, and often by pruning implements. The infected foliage initially develops small, brownish spots that turn into larger, sunken lesions and decaying spots, giving the infected shrub a blighted appearance.

Bacterial Blight

• Bacterial blight is a wilting disease that causes the infected foliage to develop brown spots before wilting and decaying. Similar to anthracnose infections, bacterial blight begins with tiny brown spots that grow into larger, dead areas. However, the brown spots are often encircled with yellowish halos. Bacterial blight infections often begin at the top of the shrub’s canopy and work their way down through the interior of the shrub. In severe infections, these destructive diseases also infect and decay a shrub’s stems and branches and cause the shrub to experience severe defoliation.

Rot

• Shrubs are susceptible to many rot diseases that can quickly debilitate and kill them. The potted shrub, however, is less susceptible to rot diseases because of its controlled environment. Still, the potted shrub can be infected with rot diseases under the right conditions. Poorly drained soil, excess watering, drought or high humidity levels can quickly hinder the health of the root system and result in an injurious rot disease.

Treatment

• Immediate treatment of the infected potted shrub reduces the potential injury. It's important to remove any infected foliage and stems with sterile shears. Repot the shrub, if necessary, to replenish the container with fresh, well-drained soil. Take the time to inspect the roots carefully during the repotting process for any signs of rot. Remove ailing and rotted roots from the root system with sterile shears to prevent the decay from spreading. Always use fresh soil when repotting your shrubs.