Knowledgebase
White cotton like mold on weeping crab #772753
Asked September 22, 2021, 6:30 PM EDT
Ottawa County Michigan
Expert Response
Hello Jeremy
The pictures aren’t clear enough to tell if this is an aphid insect, a mealybug or a scale insect. All may affect apple and crabapple species but, each insect might need different treatment.
There are a couple ways to get a diagnosis, and with that you will know how and when to control the insects.
Email the MSU Diagnostic Lab at <personal data hidden>
Submit clear pictures of:
- the whole tree including the trunk and the entire canopy,
- along with close up pictures you have here.
- Try again to get an even closer clear picture of the white substance- carefully brush away the fuzz to see if any insects or “bumps” are visible below the fuzz. If you have a macro lens for your camera, or can hold a magnifier over the camera lens, this might help. Go for a clear picture farther back, rather than a blurry shot.
They will give you an opinion along with treatments, if they can diagnose the tree. They may request a branch sample or a sample of the “fuzz”.
Another way to get a diagnosis is hire a certified arborist, a professional who has taken training in care, diseases, pests and passed certification tests. He/she will come on site and give a complete diagnosis and a plant care plan. Find certified arborists by zip code here—-
See these references for pictures of the type of insects that have these white fuzzy appearances
https://entomology.ca.uky.edu/ef219
http://treefruit.wsu.edu/crop-protection/opm/apple-mealybug/
https://www.canr.msu.edu/news/a_big_year_for_outbreaks_of_soft_scales_in_michigan