Powdery Mildew Control – Tips On Treating Powdery Mildew On Avocados

Many avocado fruits growing on an avocado tree
(Image credit: Hugo Grajales)

Avocado trees grow well in subtropical environments and make both a beautiful and a bountiful addition to warm climate gardens. These trees produce the delicious green fruits that are also nutritious. As with any fruit tree, there are pests and diseases that may strike and either kill or limit the harvest. Avocado powdery mildew is a fungus that is not uncommon, but also not too serious and easy to treat and manage.

Signs of Powdery Mildew on Avocado Trees

Avocado powdery mildew is caused by a type of fungus called Oidium. The disease only affects the foliage of an avocado tree, not the fruit. However, if the infection goes untreated and becomes severe, it can weaken the tree. In general, powdery mildew is not considered a serious disease impacting avocado trees. You are most likely to see it during the drier months of the year.

Signs that you may have powdery mildew will show on the leaves of your avocado tree. On younger leaves, look for darker green spots that are covered in a powdery substance. This is the fungus. On older leaves, the spots will become a brown or purple color with the powdery fungus.

Eventually, the powdery substance disappears and brown, net-like markings are left behind on the underside of leaves with yellowish markings on the top of the leaves.

Treating Powdery Mildew on Avocado Trees

While it is not considered a serious infection on avocado trees, powdery mildew control and treatment are important for keeping your tree as healthy as possible. If you see any signs of the fungus, treat it immediately with an appropriate fungicide to eliminate and prevent it from spreading throughout the tree.

Your local nursery, or even a local agricultural extension office, can tell you what fungicide to use. Typically, a solution of sulfur is used for treating powdery mildew on avocados.

Powdery mildew on avocado trees in your garden is nothing to be too worried about, but controlling infections like this is important for keeping your trees both healthy and attractive.

Mary Ellen Ellis

Mary Ellen Ellis has been gardening for over 20 years. With degrees in Chemistry and Biology, Mary Ellen's specialties are flowers, native plants, and herbs.