Magnolia Plant - Mold and Fungus?

Asked June 27, 2016, 7:05 AM EDT

I have had a magnolia tree planted in my back yard for 7 years. This is the first year that I've noticed a black substance (mold?) on some of the leaves. There is also a white substance (fungus?) on a few branches. I've attached some pictures I took last evening. Is this harmful to the plant? Is it normal and perhaps I've never noticed it before? (I am spending more time observing my plants this summer) What do I do to get rid of it? I've been trying to use only home made insecticidal soap or Neem Oil on my plants with spider mites (Phlox and a Ninebark bush) so not to hurt the pollinators. Assuming the black stuff is some kind of mildew, would Neem Oil get rid of, or prevent further progression of it? It is past blooming so I wonder if I have to use something stronger that it wouldn't harm pollinators? I am attaching some pictures. Thank you, Betsy

Hennepin County Minnesota magnolia

1 Response

The plant has been infested by magnolia scale. The scales excrete sticky honeydew and sooty mold grows on it. The following websites discuss magnolia scales and how to control them. The Morton Arboretum information is reliable, but to protect pollinators it's best not to use the systemic insecticides mentioned there.

http://idl.entomology.cornell.edu/files/2013/11/Magnolia-Scale-1191hjl.pdf
http://www.mortonarb.org/trees-plants/tree-and-plant-advice/help-pests/magnolia-scale-neolecanium-co...