There are many different types of bottle brush trees and shrubs, including the red bottle brush and weeping bottle brush varieties. Although generally healthy, these plants have been known to show damage from a variety of fungal diseases. These fungal diseases can be prevented with proper care of the soil and the plant.
Phytophthora root rot is a disease that infects bottle brush plants that have been exposed to overly moist soil conditions. Under wet conditions, the fungus that causes root rot grows rapidly and infects the root systems of surrounding plants. Symptoms of infection include the yellowing of leaves, early defoliation, reddish-brown roots that are brittle to the touch, the die back of branches and the discoloration of branches or the trunk of the plant. In severe cases, root rot can kill the bottle brush plant.
The best method of control is to prevent the soil below the plant from becoming overly saturated in the spring and summer months. The application of fungicides available at local garden centers has also been effective in treating this disease. Apply fungicides per manufacturer instructions.
Cankers are caused by a fungus and have been known to cause damage to bottle brush plants. (See Reference 4) Plants that have become infected will display cankers, which appear as either sunken or swollen areas on the branches or trunk of the plant. As this disease progresses and the fungi spreads, it is capable of stunting the growth of the plant and even killing branches or the entire tree.
Infected areas of the plant should be pruned and disposed of. Fungicides can also be purchased at local garden centers and applied per manufacturer instructions to control this disease.
Twig gall is a fungal disease caused by Sphaeropsis tumefaciens. This disease is known to infect a number of woody ornamentals, including the bottle brush. Bottle brush trees infected with twig gall may have branches that have become enlarged and swollen. Another common symptom of the disease is the presence of many shoots coming from the branches and trunks of diseased plants. As this disease progresses, it can cause severe damage to the plant.
Control twig gall by preventing the soil around the plant from becoming overly saturated with water, thus promoting the growth of the fungus that causes the disease. Branches that show signs of this disease should be pruned and disposed of. After every cut, sterilize the shears to prevent the spores of the fungus from being spread to other branches or neighboring plants. This fungal disease loves warm, moist climates and is the most prevalent in bottle brush trees planted in Florida and the Caribbean.