Seiridium Canker: The Cause of Sap Leakage in Italian Cypress

An Italian cypress exhibiting heavy resin flow down the trunk and lagging height growth compared to neighboring trees is likely suffering from Seiridium canker, the most damaging disease affecting cypress species.

Disease Identification

Seiridium unicorne causes sunken, dark brown to purplish cankers on stems, branches, and branch axils, often accompanied by copious resin exudation. However, resin flow alone isn't diagnostic—healthy cypress also exude resin. Key indicators include scattered twigs turning bright reddish-brown against healthy green foliage, and tiny black fruiting bodies on canker surfaces.

Disease Spread

Spores disperse via water splash from rain or irrigation, and contaminated pruning tools. Long-distance spread occurs through infected nursery stock. The fungus affects plants of all ages and sizes.

Management Strategies

No chemical controls are recommended for landscape trees. Cultural management focuses on:

• Pruning and destroying infected branches at least 1 inch below visible cankers
• Sterilizing tools between cuts (70% alcohol or 10% bleach solution)
• Avoiding water stress and mechanical wounding
• Removing severely affected trees entirely

Prognosis

While incurable, diligent sanitation can slow progression. The tree's height deficit suggests chronic infection. Monitor nearby cypress for early symptoms.