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University of California Cooperative Extension Ventura County
669 County Square Drive, Suite 100
Ventura, CA 93003
Phone: 805.645.1451
Fax: 805.645.1474

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Office Hours:
Monday - Friday from 9 a.m. to 4 p.m. 

The office will be closed for the following holidays:

May 27 – Memorial Day
June 19 – Juneteenth
July 4 - Independence Day

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Cypress Canker

The causal fungus is most active during the rains of late winter and spring. Fungus spores are dispersed and infect the living bark and cambium, progressively killing tissue. This results in the death of branches, and sometimes the top of a tree, and in time the whole tree as the fungus invades new tissues. Usually, the first symptoms are pale green, then yellowing of affected portions of the tree, followed by death. Where the fungus has invaded the wood, a canker develops, followed by moderate to heavy resin flow around the canker. Diseased limbs can be pruned out. The whole limb should be removed and burned, chipped, or buried as branches left in a brush pile will liberate fungus spores for several years. Dead trees should be removed and destroyed (burned, buried, or chipped, and the wood composted). The principal hosts for cypress canker are Monterey cypress, Italian cypress, and several cypress hybrids — Leyland, Lusitania and Arizona cypress, plus Cupressocyparis bethamii, and C. macnabiana. Juniperus virginiana is also moderately susceptible. It is best not to replant new cypress immediately following the removal of diseased trees.