Star Magnolia Scale

Asked April 1, 2019, 10:29 AM EDT

We have a star magnolia, about 5 years old, about 6-7 feet tall, that developed scale. We had thousands of bees last summer. We were advised by Bachman’s to spray some insecticide and we used bee spray several times. So here we are in spring, with the tree limbs covered with these dark spots and this dark colored soot. A horticulturist at Bachman’s told us an intensive process to control the scale, and we would not be able to totally remove all of the scale. In the short term, they suggested using an oil now before the tree blooms, and then use a soil treatment so the tree can get treated through its roots. They suggested removing the tree in order to prevent the birds from spreading the scale. Before we do that, I’d like your opinion. Can we save the tree and if so, how? What would you suggest? And if we take the tree down, what small ornamental tree could we replace it with? And do we need to treat the soil before replanting a tree in the same spot?

Hennepin County Minnesota magnolia scale

1 Response

Magnolia scale is very difficult to control. Here are a couple of links that explain it as well as the proper timing of treatments. https://hortnews.extension.iastate.edu/magnolia-scale , https://hort.extension.wisc.edu/articles/magnolia-scale/ . As far as replacing it goes only certain varieties are most susceptible. I would consider another ornamental rather than another magnolia in that spot. Here is a link to some tree choices to consider but a trip to your local nursery or the arboretum to look at trees is also another possibility. https://extension.umn.edu/tree-selection-and-care/recommended-trees-minnesota#southeast-minnesota-ec...