Seiridium canker, or Cypress canker, was first reported in California in the late 1920s and has since spread throughout North America and into Florida wherever Cupressaceae (cypress family) grow. Leyland cypress can be killed or severely disfigured by the disease. This 4-page fact sheet describes the causal agent, host range, symptoms and signs, disease cycle and management, and recommends tree replacements with resistance to Seiridium canker. Written by Jason A. Smith, and published by the UF Department of School of Forest Resources and Conservation, November 2010.
http://edis.ifas.ufl.edu/fr341