what is the white powdery substance on my Dogwood tree bark?

Question: I was surprised to find my dogwood bark covered with a white powdery substance (fungi?)   The material is powdery and can be removed with a soft bristle  brush.   I'm concerned about how this material will affect the health of the tree?

responder: Thank you for your question!   Laura S.      Michigan State University Extension Advanced Master Gardener Volunteer You may also contact the toll free MSU Extension lawn and garden hotline at 1-888-678-3464 with your gardening questions or visit www.migarden.msu.edu for Smart Gardening resources. Replied September 10, 2024, 2:54 PM EDT
response: Hi Randy, Your pictures are blurry but, it is likely scale insects, perhaps white prunicola scale. Here is a bulletin to compare with what you see. https://extension.umd.edu/resource/white-prunicola-scale/  Each scale insect must be treated at the correct time in its lifecycle. So, we need to identify this scale insect.  Please try to get some clear close up pictures of a branch with the scale. Use good light, from about 7-9 inches away. We can magnify a clear image, but magnifying a blurry one will not help.  Other ways to get a positive ID: Submit a branch sample to the MSU Plant Diagnostic lan. Instructions and fee schedule are here— https://www.canr.msu.edu/pestid/ Hire a certified arborist to come on site and diagnose the tree. Search for certified arborists here- http://www.treesaregood.org

responder: The Question Asker Replied September 10, 2024, 3:58 PM EDT
response: Laura Thank you for your quick response.  Here are a couple other photos that hopefully are better for you to diagnose.  At the risk of being wrong I have brushed off the majority the powdery substance.   I have not seen any bugs associated with the growth. Regards, Randy Sent from Mail for Windows From: Ask ExtensionSent: Tuesday, September 10, 2024 2:54 PMTo: Randy SchroederSubject: Re: what is the white powdery substance on my Dogwood tree bark? (#0154676)

responder: Thank you for your question!   Laura S.      Michigan State University Extension Advanced Master Gardener Volunteer You may also contact the toll free MSU Extension lawn and garden hotline at 1-888-678-3464 with your gardening questions or visit www.migarden.msu.edu for Smart Gardening resources. Replied September 10, 2024, 6:12 PM EDT
response: Hello Randy, Thank you for the close ups. These actually appear to be woolly aphids. Scale insects would not brush off easily, aphids can be forced off with a strong stream of water. I am going to ask our entomologist to give an opinion. Have you noticed any stickiness on the branches or on the leaves? Laura

responder: The Question Asker Replied September 10, 2024, 8:17 PM EDT
response: Hi LauraNot sticky -- dry to touchThx for your helpRandySent from my iPhone On Sep 10, 2024, at 6:12 PM, Ask Extension wrote:﻿

responder: David Lowenstein  Replied September 11, 2024, 11:03 AM EDT
response: I've spoken with some colleagues, and we agree this is white prunicola scale (Pseudaulacaspis prunicola) . It does not produce honeydew. These brush off easily. If you choose to use a chemical treatment, I'd suggest a dormant oil application in February/March.

responder: The Question Asker Replied September 11, 2024, 5:02 PM EDT
response: We so grateful to know this -- thank you so much --  I will look up and try to learn more about this white scale --We would hate to lose the dogwood as it is a memory tree we got when my wife's dad died 20 yrs ago --Regards RandySent from my iPhone On Sep 11, 2024, at 11:03 AM, Ask Extension wrote:﻿