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Magnolia Scale Info / Symptoms:

Magnolia Scale is one of the largest scale insects in Illinois reaching up to a half of an inch in length. It can also be fairly difficult to treat large infestations. Magnolia Scale will overwinter on twigs on the tree, then start to feed and enlarge throughout spring. Female scale will turn from white to a brownish-purple color and will become fully mature in July. Mature females will then lay their eggs underneath their shell and will protect them until the juvenile scale emerge from the shell in August.

Control Methods:

For complete control of Magnolia Scale there is a 3 step process listed below. Large infestations of Magnolia Scale may take more than one year in order to be fully cleared.

Application #1
Mix Annual Tree & Shrub Drench with water and apply it at the base of the plant. It takes 4-8 weeks for the plant to take up the drench and kill the scale. It can be used as a preventative once a year, preferably in fall or spring, or upon detection of insects in July.
Application #2
Spray Systemic Insect Control to target the juvenile crawler stage of the insect. Spray three applications directly on the branches / twigs of the tree. The first spray should be in late August, then again in mid September, and again in late September.
Application #3
Spray All Seasons Horticultural & Dormant Oil in winter/ early spring while the tree is dormant and before leaves appear.
Click Here to Download a PDF version of the handout
https://www.youtube.com/watch?v=BxBHizb1Fhg
Check out Matt’s video on how to identify and treat Magnolia Scale
Photo by (onetree.ca)