The Cypress tree is an evergreen variation that consists of more than 140 species. This family, the Cupressaceae family, includes species such as the Juniper, Arizona Cypress, Italian Cypress and the Eastern Redcedar. Cypress trees have needle-like leaves and produce cones as fruit. While each species has varying drought and flood tolerances, most are moderately to fast growing trees that are mostly disease resistant. Still, the cypress is susceptible to several fungal diseases.
Cercospora Needle Blight
Cercospora needle blight overwinters within the microscopic crevices of cypress needles. During springs wet period, the fungal spores are released, infecting the needles of the tree. Infected cypress trees will display browning and wilting of its needles. The browning generally begins at the base of the tree and moves upwards as the disease progresses. Severely infected needles will die. Cercospora needle blight is easily controlled with fungicidal spray treatments which must be applied in the mid to late spring for full effectiveness. An additional treatment in the early fall provides additional protection.
Seiridium canker is a chronic fungal disease that is especially damaging to the Leyland cypress tree. The disease affects trees of all ages. Cypress trees infected with seiridium canker develop dark colored patches on bark and branches. These spots develop into sunken cankers which often ooze fungal resin. Infected twigs and branches eventually die from the disease. Deadened areas display a reddish brown color which may also include fruiting fungal bodies. Chemical treatments are not available for seiridium canker. Infected areas should be pruned from the tree to reduce the effects of the disease.
Phomopsis Tip Blight
Phomopsis tip blight infects the new growth of the cypress tree's needles. Like many fungal diseases, the fungus lies dormant in the twigs and bark throughout the winter months. Emerging in the spring, the fungus infects the succulent needles and any wounds on the tree. Infected cypress trees will experience dieback of shoots and needles. The infected areas will develop small fungal bodies that are especially prominent on deadened areas. This disease is especially detrimental to juniper trees. Good ventilation and proper watering and drainage will reduce the potential for phomopsis tip blight. Infected areas should be pruned from the tree, approximately two to three inches away from the point of infection. Fungicidal sprays are effective in treating the infection.