Magnolia trees are beautiful to behold. They are one of the first trees to bloom in the spring and come in a colourful assortment of species, which help to chase away the late winter doldrums. But magnolia trees are not immune to problems and CLC Tree Services has had several calls this year about them.
“Why isn’t my magnolia tree thriving?”
Of the magnolia trees that CLC Tree Services has inspected, we have sadly seen a lot of bugs. Magnolia trees are susceptible to magnolia scale, which is often not noticed until a tree is heavily infested. When a client calls because they have noticed the leaves on their beloved magnolia are yellowing or have black sooty mold on them, the problem invariably has been going on for 3-4 years already. But the good news is that there is usually still hope and something which can be done against this insect infestation.
Picture of Magnolia Scale by William Fountain, University of Kentucky, Bugwood.org
Magnolia scale is a large soft scale insect. The 1/2″ scales look like small bumps on twigs and branches. In fact, those elliptical bumps are the insect and they suck the sap out of your tree, effectively weakening it. To make matters worse, they excrete a sweet liquid, called honeydew, which attracts wasps and hornets.
Mature females are pinkish orange to dark brown in colour and often have a white waxy coating on them. Their young are called crawlers and this is the only time in their life in which they are mobile. They creep along branches until they settle down to feed and then permanently attach themselves to whichever branch they have settled on. As they age, their shell (exoskeleton) hardens, making them more impervious to predators and insecticides.
While magnolia scale left untreated can weaken limbs and eventually kill a tree, there are remedies you can use to combat an insect infestation. Remove mature females in early July before crawlers emerge, making sure not to damage the tree’s bark. Prune out heavily infested branches.
Magnolia tree in bloom
When that is not enough, a dormant oil can be applied to the entire tree. The tree needs to be entirely coated; essentially suffocating the scale. At least 2-3 applications are necessary—usually in early spring and late fall—to kill all the scale and any crawlers that persist.
While treatment is not cheap, neither is cutting down your tree, nor is replacing it with a much smaller specimen. Don’t forget the benefits lost when a mature tree is removed (ie. shade, beauty, wind buffer, erosion control, etc.). And even if you choose the route of tree removal, scale can persist in the soil and reinfect any new magnolia trees planted in the same area. Which means that if you want to admire a magnolia tree of your own, treatment is necessary.
The good news is that CLC Tree Services can help. If you notice sooty mold on your magnolia tree’s leaves, reduced flowering or smaller leaf out, give us a call. We can advise you on a course of action, and if that includes treatment, we are certified to apply insecticides.
Call 519-685-0257 today.