Magnolia scale shows up as small, shell like bumps on the bark and branches of a magnolia, usually along with sticky honeydew and black sooty mold on the leaves below. The insects feed on sap beneath those shells, so the bumps, the stickiness, and the blackened leaves together point to a scale problem.

What does magnolia scale look like on the tree?

Small, shell like coverings fixed to the bark and branches, which can read at first as rough patches or growths on the wood. Each covering hides an insect feeding on the tree's sap, and the bumps tend to gather along the twigs and branches rather than on the leaves.

What other signs point to magnolia scale?

A sweet, sticky residue called honeydew, which the insects excrete and which drips onto the leaves and anything beneath the tree. Black sooty mold then grows on that honeydew, and a heavily infested magnolia can also show yellowing, stunted growth, and general weakening.

How is magnolia scale treated once it's identified?

With horticultural oil applied to the wood where the insects feed. Spraying Horticultural Oil Insect Spray onto the trunk and branches during the growing or dormant season, though never while the tree is in flower, helps manage the scale, and controlling the scale is what keeps new sooty mold from forming.

Frequently Asked Questions

Is there an option for a magnolia too large to spray?

Yes. When the branches are out of reach, Once A Year Insecticidal Drench w/Merit can be poured around the base before flowering, giving the tree 12 months of protection against scale.

Can horticultural oil be sprayed while the magnolia is blooming?

No. Spraying is skipped during flowering and done in the growing or dormant season instead.

Do other scale insects attack magnolias?

Yes. Magnolias can be susceptible to other scale insects as well, which bring similar yellowing and stunted growth.

Will the black leaves clear up once the scale is treated?

Not on their own. Controlling the scale stops new sooty mold from forming, and the guide to black magnolia leaves covers removing what is already there.