Identifying and Treating Harmful Acacia Diseases

Acacia on a white background.
What You'll Need
What You'll Need

Acacia are beautiful flowering trees that can enhance the aesthetic of any home or garden. They grow in a wide variety of climates and are easy to care for. Like all flowering trees, however, acacia diseases — powdery mildew, stem cankers, and other conditions— may threaten your acacia trees. Read on to learn about some of the most common diseases of acacia plants, and how to identify and treat them effectively.

Identifying and Treating Powdery Mildew

Powdery mildew is a disease caused by one of several fungi. Although there are a variety of fungi that cause slightly different conditions in acacias, they may be grouped together under the same category of powdery mildew.

Powdery mildew is named such because the condition is denoted by a powdery white coating over the leaves, branches, and other parts of a tree. This coating is actually fungal spores that grow over the surface of the acacia. Left untreated, these fungal spores may prevent the tree from receiving the nutrients that it requires, killing part or all of the plant.

It may be difficult to identify powdery mildew initially, as it typically first appears as a small, patchy section. However, these white spots expand and thicken quickly, and a close observer is likely to catch powdery mildew before it advances very far. Powdery mildew typically develops late in the blooming season.

Management of powdery mildew may be accomplished with a fungicide. Consult with a gardening center for a list of appropriate fungicides for use with acacia. Incorrect fungicide can damage the plant itself in addition to the fungus in question. If you prefer not to use fungicides to treat the powdery mildew affecting your plants, you may also attempt to remove the parts of the tree that are damaged by the fungus. However, this is not a surefire treatment method. Fungal spores may still exist in the area.

Identifying and Treating Stem Cankers

An acacia tree.

Generally, a canker is a section of a tree where the bark is damaged or missing. Cankers are wounded areas and do not typically develop on their own. If cankers develop in certain crucial areas of the tree, or if a canker becomes large enough that it compromises an entire section of the tree, you may need to cut a large section of that tree or perhaps even have it removed entirely.

Stem and other types of cankers are also caused by fungal infections. Left untreated, a cankerous tree poses a threat to other plants in the vicinity. Watch for oozing or unusually dark sections of the branch or trunk of your tree. If a canker develops, take immediate action to prevent further damage.

Cankers are not treatable with fungicides or other chemicals. The canker and surrounding areas must be excised and removed from the tree. In some cases, this may require felling the entire tree.

If you suspect that your acacia suffers from powdery mildew, stem cankers or some other tree disease or condition, consult with a gardening expert for advice on how to best control the situation and prevent recurrences. Doing so is your best chance of saving the tree and the surrounding flora.