Italian Cypress Canker
Some in the business incorrectly diagnose the dead brown spots in the plants as spider mites. There might be some mites on the plants as a secondary issue; however, the real culprit is a fungal canker. Seiridium cankers can attack most members of the Cupressaceae family. These cankers are caused by one of three different fungal pathogens (Seiridium cardinale, S. cupressi and S. unicorne).
This pathogen is spread via wind by the fruiting bodies or spores but the plant susceptibility results from stress in the plants. Initially, the spores colonize in the bark of the tree, causing lens shaped lesions, black colored blisters and red sunken lesions that produce sap. The first signs that most homeowners notice are dying branches and brown spots in the foliage. At that point, treatment is needed quickly. Without attention and correction, the fungus could eventually kill the entire tree.
Some tree companies recommend treating trunks with injections of pest control products and some of those can help. However, this type treatment is temporary. The better approach is to relieve the stress that invited the pathogen. To do that Italian cypress must be in full sun all day long. If that’s not the case, start thinking about replacements. Second, the drainage must be excellent. Third, stop overwatering! And finally, apply the Sick tree Treatment with the first step (of course) being the removal of mulch and soil from the base of the trees (from the root flares). Eliminate the toxic chemicals, fix soil compaction if needed, go organic and enjoy your healthy gardens and trees.