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Black mold on some leaves of magnolia bush #942706

Asked August 17, 2026, 4:38 PM EDT

What can I do about black, powdery-like mold on some leaves of my magnolia bush?

Carver County Minnesota

Expert Response

Thank you for writing.
Although you did not send a picture, I am reasonably sure this is sooty mold, explained here. https://extension.unh.edu/blog/2018/07/why-are-leaves-my-magnolia-turning-black-attracting-wasps
The problem is that if it is caused by magnolia scale, this can turn into a very serious problem very quickly.
I would like a close up picture of a couple leaves and a careful search and photograph of magnolia scale.
https://hort.extension.wisc.edu/articles/magnolia-scale/

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 August 17, 2026, 4:55 PM EDT

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This work is supported in part by New Technologies for Ag Extension grant no. 2020-41595-30123 from the USDA National Institute of Food and Agriculture. Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture.

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