Azalea bushes are susceptible to a variety of fungi that may create severe injury on your home garden plants with the potential for plant death. Provide the essential preventive care to your bushes for vigorous plants that may resist or fight fungi. Familiarize yourself with what to look for as well as reliable control methods should fungus attack your azaleas.
Vigorous azalea bushes are much more likely to resist attack or have the capability to fight off fungal infections when compared to stressed or injured plants. Grow azaleas in areas that offer partial shade, like beneath a tree that filters sunlight, according to the Clemson University Extension. Excessive sun may cause injury. Azaleas thrive in well-drained, acidic soil with a pH of 4.5 to 6.0. Wet sites are ideal for the germination of fungi, so avoid waterlogged soil.
Different types of fungi affect azaleas in a variety of ways. Root and crown rot is an infection of azalea bushes caused by the fungus Phytophthora. Fungi live in water and infect the roots of your plant. Another widely observed problem is dieback, a fungal infection caused by the fungus Botryosphaeria dothidea that primarily infects one branch of your azalea plant, according to the Clemson University Extension.
Root and crown rot of azalea bushes is one of the most common fungal infections of the home garden. Once fungus takes hold of your plant, you may notice curled leaves and brown stem bases as well as black, softened roots, according to the Clemson University Extension. This fungus can severely injure or kill your plant as rotten roots inhibit azaleas from the ability to absorb water and nutrients. Dieback of azalea bushes results in plants that often look healthy but display dead leaves as well as discolored wood on one branch when bark is stripped away. Look for a red to brown color on affected wood. One or more branches of your azalea bush will die under this infection.
When selecting and planting azalea bushes, choose resistant varieties or those known as the least susceptible to lower the incidence of infection by fungus. For root and crown rot, resistant varieties include, but are not limited to, "Corrine," "Glacier," "Merlin" and "Polar Sea," according to the Clemson University Extension. For dieback, those azaleas considered the least susceptible are "Pink Gumpo" and "Snow."
For control of root and crown rot of azalea bushes, depend mostly on planting resistant varieties and proper care. Fungicides are effective but will only control the problem without curing it. These fungicides contain the active ingredients metalaxyl or mefonoxam, according to the Clemson University Extension. For control of dieback on azaleas, handle plants with care to avoid creating wounds through which fungi invade. Apply a fungicide with the active ingredient mancozeb. For both problems, sanitize pruning tools between each cut and from one bush to the next to prevent fungal spread.
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