I have a 25 year old magnolia tree that has white spots all over its branches. It has just happened. It’s also oozing honeydew. I read that I should spray with water but it hasn’t helped. Is there anything else I can do for this tree. I don’t want to loose it.
It sounds very much as if your magnolia tree is infested with scale. Scale insects suck the sap from the limbs of magnolia trees and excrete a sweet, sticky substance called honeydew that drops on everything below, attracting wasps, bees and flies. A fungus, called sooty mould, grows on the honeydew, turning everything black, which is unsightly. Magnolia scale infestations appear at this time of year with a vengeance. The actual scale can be 13mm in diameter, they are brown and hemispherical and are covered with a layer of wax. A tree under heavy attack will be encrusted by white nodules, which is probably what you have noticed. If left untreated, the infestation could kill the tree. Scale are resilient because they are covered by this waxy substance. The application of dormant oils can be useful in controlling these insects.
Previous responses to this question should be helpful in controlling scale. They are posted on the Toronto Master Gardener website at:
Depending on the severity of your infestation you may decide to contact a specialist. We suggest you begin your search for a certified arborist at the website of the Ontario chapter of the International Society of Arboriculture or ISA Ontario, see link below.
Another good option would be to contact Landscape Ontario and search there for a recommended professional in your neighbourhood, to care for your trees. Also, see link to their homepage below.