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Thursday - April 01, 2010

From: Hillsboro, OR
Region: Northwest
Topic: Diseases and Disorders, Trees
Title: Why are my lemon Cyprees trees turning Black?
Answered by: Jimmy Mills


I have 3 lemon Cypress plants - all are about 6 feet tall. One of them has started turning black on one side - like it's been burnt. The inside of the plant is also turning black. I assume something is eating it from the inside out. What can I do to stop it?


Lemon Cypress is a cultivar called Goldcrest or Golden Crest of  Cupressus macrocarpa (Monterey cypress). This link from Floridata provides general information about the plant.

The TopiaryShop recommends checking your plants for aphids. They secrete a substance called honeydew which can give the plant a black sooty appearance from sooty mold growing on the honeydew.

It is difficult for us to diagnose plant diseases from a distance, so I'm going to suggest that you contact the folks at the Washington County Office of the Oregon State University Extension Service for some help closer to home.



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