Knowledgebase
Leland cypress trees #482154
Asked August 31, 2018, 7:03 PM EDT
Josephine County Oregon
Expert Response
Diseases that result in browning of Leyland cypress often occur on stressed, weakened trees. Providing the right care is many times all the prevention needed to maintain healthy cypresses. Leyland cypress grow best where they get full sun to partial shade. With a preference for moist, well-drained soil with good fertility, Leyland cypresses will continue to develop well under most conditions, including acid or alkaline soils and occasionally wet soil.
This could be a sign of a fungus called Seiridium cardinale (formerly Coryneum cardinale. Symptoms include old foliage that yellows and browns in spring, followed by a fading green or death of new foliage. Small branches are infected first, then larger ones. A typical lens-shape, sunken canker can be found on the branch below affected foliage. Top death and dieback are common. Bark turns brown, and small, black fruiting bodies (acervuli) may form in the cankered area. Drops of resin frequently are in and at the sides of cankers. The expansion of cankers is slow on large branches and trunks of mature trees. Could be confused with Monochaetia canker.
Cultural control
- Plant resistant cultivars.
- Remove and destroy affected branches 1 to 2 ft below the canker. Sanitize pruning tools between cuts.
- Avoid water stress and wounding trees.
Here are a couple of publications that may help.
https://pnwhandbooks.org/plantdisease/host-disease/cypress-cupressus-spp-canker
https://www.uaex.edu/publications/pdf/FSA-7536.pdf
Hope this helps!