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Question
All my 9  Italian cypress trees are sick. They look beautiful but 10 days ago I saw a small dead branch and discovered several  black oozy lesions on the trunks. Since then I have been reading about the diseases of cypress trees and I believe they have canker. I am so sad that I am  probably going to lose them.
. I live in Southern California close to the ocean. The trees are 10 years old and I would like to do everything reasonable to save them.

Is there anything new? Could Phosphoric acid injections or infusions really cure them?

Thank you for your help.

Answer
Sounds like a disease called Seiridium canker. The under lying cause is stress on the tree by usually weather condition.
Seiridium canker, caused by Seiridium unicorne, is probably the most damaging disease on cypress. Plants of all sizes and ages are affected. Cankers may form on stems, branches and in branch axils causing twig, branch or, at least on smaller plants, stem dieback. Cankers appear as sunken, dark brown or purplish patches on the bark, often accompanied by extensive resin flow. It should be noted that resin exudation often occurs from the branches and stems of otherwise healthy plants of  cypress thus resin flow by itself is not a diagnostic characteristic for Seiridium canker. Scattered twigs or branches killed by the fungus turn bright reddish brown, and are in striking contrast to the dark green healthy foliage. Fruiting bodies of the fungus appear on the bark surface of the cankers as small circular black dots barely visible to the naked eye. Spores of the fungus are spread to other parts of an infected tree, or from tree to tree by water splash from rain or irrigation. The fungus also can be spread from tree to tree on pruning tools. Long distance spread appears to be through the transport of infected cuttings or plants.

Currently there are no chemical control measures recommended for the disease in the landscape or nursery. Avoiding water stress and tree wounding may reduce infection. Infected branches or twigs should be pruned and destroyed as soon as symptoms are noted. Prune at least one inch below the canker, and sterilize the pruning tools between cuts by dipping them in rubbing alcohol or in a solution of 1 part chlorine bleach to 9 parts water. Tools should be cleaned and oiled after using bleach to prevent rusting. Severely affected plants should be removed and destroyed.  

Here is a link to more information on this disease.

http://cals.arizona.edu/pubs/diseases/az1557.pdf

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Jim Hyland

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I am an expert in Forestry, Forest Entomology, Forest Pest Control, and Forest Health. Extensive knowledge in Identification of insects and diseases of trees. Expert on Bark beetles and other insects that attack forests. Also a Registrated Forester with extensive knowledge in the management and care of forests.

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34 years as State Pest Management Chief in a Southern state. Extensive knowledge in Forestry.

BS with major in Forest Management and Entomology
Registered Forester
Certified Pesticide Appicator

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