Sirococcus tip (shoot) blight
Sirococcus conigenus (S. strobilinus)
Spruce and Pine
Distribution and Disease Cycle
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
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.
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.
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