White Blotches on Tree bark

Asked April 9, 2016, 11:10 PM EDT

I have just noticed on two trees...a Lyiac tree and a weeping cherry tree white blotches on the bark (never have seen them before). The Lylac tree is really green and doing well with its blossoms the weeping cherry tree seems like its blossoms died early and has few leaves. Can you help by looking at the pictures? Thank you

Washington County Oregon plant disease

1 Response

The white crusty growth in your first picture closely resembles a crustose lichen, Phlyctis argena. See picture here http://pnwhandbooks.org/plantdisease/pathogen-articles/nonpathogenic-phenomena/algae-lichens-and-mos...

Lichens are fungus and algae living in association. These are not pathogenic. Just like mosses, lichens become established on slow-growing plants in moist and humid conditions. Therefore, it helps to improve plant vigor by proper fertilization, watering, and cultural management. Reduce moist and humid conditions which favor their growth by opening up the plant canopy to allow better air circulation and light penetration. Because of the favorable climate in PNW, these practices probably will not eliminate the lichens but they will reduce their number and vigor.

There are some chemical management options like copper-based fungicides and lime sulfur. In order to use the fungicides, you must find the plant that you want to spray listed on the label. If you are considering chemical control, please carefully read this article for further details http://pnwhandbooks.org/plantdisease/pathogen-articles/nonpathogenic-phenomena/algae-lichens-and-mos...

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