Landscape - Seiridium Canker

The following is information on Seiridium canker, a disease that is being found more and more on Leyland Cypress.

Seiridium canker has been seen on leyland cypress. Stressed trees are more susceptible to this damaging fungal pathogen. Cankers are formed on main trunks, branches or twigs, and appear as sunken, dark areas. Resin flow or ooze will often be noticeable from the canker areas, but resin is not a diagnostic feature alone because it can be due to other factors. Affected branches often turn a reddish brown. Fruiting bodies may be found in the cankers with the aid of a hand lens or microscope. Spores are spread by water splash or mechanical means on pruning tools. There are no chemical controls for Seiridium canker in the landscape. Reduce drought and other stress on trees. As spores may be spread by pruning and wounding, take care in pruning out diseased areas. Prune at least one inch below cankered area and clean pruners in alcohol or 10% bleach. Remove and discard trimmings.

Photo by Tracy Wootten, Extension Horticulture Agent, UD, Sussex County.

Information from Nancy Fisher Gregory, Plant Diagnostician, Department of Plant & Soil Sciences, University of Delaware