Cytospora Canker

    Cytospora Canker

    Leucostoma sp.

    cytospora

    Cytospora spores oozing from branch (Claudia Nischwitz, Utah State University Extension)

    cytospora

    Cytospora canker on spruce (Jospeh O'Brien, USDA Forest Service, Bugwood.org)

    cytospora

    Fruiting structures on a dead branch (Melodie Putnam, Oregon State University)

    Hosts, Symptoms & Signs

    • many deciduous trees; spruce
    • branch dieback; cankers develop that are oval shaped
    • fruiting structures develop on bark at canker or on dead branches
    • weak pathogen; healthy, vigorous plants do not get infected
    • ttacks stressed trees through wounds caused by pruning, insect feeding or winter injury or by other pathogens

    Disease Cycle

    • overwinters as fungus in the bark
    • produces fruiting bodies that ooze spores in spring
    • splashing water (irrigation or rain) spreads spores to neighboring branches or trees; if the spores land on a stressed tree in a wound, they germinate and start colonizing the tree, creating a canker over time
    • severely infected trees will die within a few years; sometimes a tree is able to wall off an infection site and confine the pathogen; it will continue to live but it will have the canker present for the rest of its life

    IPM Recommendations

    • Avoid mechanical and winter injury.
    • Prune dead branches in the winter and burn them (infected branches should be cut 4 inches below the end of the canker). Disinfect pruning tools between cuts using a 10% bleach or 70% alcohol solution or disinfecting wipes.
    • Plant disease-free plants (avoid planting trees that already have dead branches).
    • Control insects and other diseases.
    • There are no effective fungicides available.