Seiridium is a genus of plant pathogens in the family Sporocadaceae.

Seiridium cardinale is important to gardeners and foresters as they cause the devastating Cypress canker disease on Cupressus, Thuja, and related conifers in Northern Europe, America, Australia, and New Zealand. Seiridium cardinale is from California and was introduced to Europe around the 1930s, probably from infected nursery stock. A separate introduction affected the southern hemisphere.

...