See:
Cypress (Cupressus spp.)-Canker
Cause Seiridium cardinale (formerly Coryneum cardinale), a fungus. There have been 15 samples with Seiridium Canker sent into the OSU Plant Clinic over the years. The fungus can infect many genera of the Cupressaceae including Chamaecyparis, Juniperus, and Thuja, as well as hybrids such as Leyland cypress. Spores are rain splashed; the fungus also can be moved on pruning tools and infected nursery stock. It enters trees through natural occurring wounds or insect damaged tissue. Favored by prolonged periods of mist and light rain with moderate temperatures. Cankers enlarge faster on drought-stressed trees.
Symptoms Old foliage 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.
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.
Chemical control Use before fall rains.
- CuPRO 5000 at 1.5 to 5 lb/A but only up to 2 lb/A when new growth is present. Group M1 fungicide. 48-hr reentry.
- Empress at 1 to 3 fl oz/100 gal water. Group 11 fungicide. 12-hr reentry.
- Fore 80WP Rainshield at 1.5 lb/100 gal water plus a spreader-sticker. Group M3 fungicides. 24-hr reentry.
References Graniti, A. 1998. Cypress canker: A pandemic in progress. Annual Review of Phytopathology 36:91-114.