Sirococcus tip (shoot) blight

Sirococcus conigenus (S. strobilinus)

Hosts

Spruce and Pine

Distribution and Disease Cycle

Description of this image follows
Sirococcus tip blight on pine.
Photo credit: Tom Nichols, USDI National Park Service, Bugwood.org

This fungal disease overwinters in infected shoots, needles, cones and seeds, with spores dispersed by rainfall during spring and summer. Infections begin in the needles of current year's shoots, spreading to the stem producing cankers in succulent stem tissue. Fruiting bodies form on dead shoots, producing spores that spread by rain or irrigation to nearby host tissue. If conditions are suitable (cool, humid, shady), spores germinate and infect current year's shoots. Infections can cause restricted growth, stress, unsightly appearance, or even death in younger seedlings.

Symptoms and Signs

Description of this image follows
Sirococcus conigenus, the causal agent of Sirococcus shoot blight, fruiting on white spruce.
Photo credit: Natural Resources Canada, Canadian Forestry Service.

Symptoms of Sirococcus tip blight include curling needles, hook-shaped shoots, tip dieback and/or cankers on current year's growth, with lower branches usually affected first. Needles distant from active infection become chlorotic and die, turning reddish-brown before they are shed. Fruiting bodies form on bud scales or other parts of dead shoots. Symptoms can be similar to winter browning or frost injury but the distribution is typically more scattered.

Control

If practical, prune and destroy infected shoots. In severe cases, apply chlorothalonil SU beginning in November as per the label instructions at 2 to 4 week intervals as required.

Date modified: