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mold or insect infestation? #879189

Asked July 29, 2024, 9:35 AM EDT

I discovered these while spots on my magnolia bush. When taken off and squeezed, an oily black substance emerges. Is it mold or insect? How do I (and should I) deal with this to keep my plant and yard healthy?

Dakota County Minnesota

Expert Response

Thank you for writing.
That is classic magnolia scale. It is killing magnolias all over MN.
https://northerngardener.org/magnolia-scale/
Measures to treat it are described but in truth, magnolia is not succeeding in MN these days.
https://mortonarb.org/plant-and-protect/tree-plant-care/plant-care-resources/magnolia-scale-neolecanium-cornuparvum/
Steve Miles, Master Gardener, Hennepin County, (I am a volunteer human being: not a bot, not AI). I'm an avid gardener but not a degreed or certified horticulturist or arborist. I will do much better if you also send a photograph. I like follow-up questions.  The University' garden soil tests are excellent.  https://soiltest.cfans.umn.edu/testing-services/lawn-garden This is how to find a tree expert.  https://extension.umn.edu/planting-and-growing-guides/how-hire-tree-care-professional  A Directory of ISA certified arborists is at https://certificates.directory.isa-arbor.com/  The Minnesota Landscape Arboretum is a wonderful place to see and learn about plants that grow in Minnesota. https://mngardens.horticulture.umn.edu/minnesota-landscape-arboretum  Ask a Master Gardener is a public service of the University of MInnesota's Extension Division.  Please donate if we make you happy.  https://give.umn.edu/gardener Replied July 29, 2024, 1:40 PM EDT

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