Anthracnose

    Anthracnose

    Apiognomonia spp.;  Discula spp.; Kabatiella spp.

    anthracnose

    Anthracnose on canyon maple (Marion Murray, Utah State University Extension)

    anthracnose

    Anthracnose on sycamore (William Jacobi, Colorado State University, Bugwood.org)

    anthracnose

    Anthracnose trunk canker on sycamore (William Jacobi, Colorado State University, Bugwood.org)

    Hosts, Symptoms & Signs

    • sycamore, maple, oak
    • all three species show irregular-shaped necrotic lesions on leaves often on veins or on the margins
    • on sycamore, new shoots show wilting and dieback
    • cankers can develop on branches and trunk
    • clusters of dead and live branches may form “witches’ brooms” from repeated dieback
    • premature leaf drop late spring/early summer on maple and oak
    • dieback of newly emerging shoots and expanding leaves on oak

    Disease Cycle

    • overwinters in buds, twigs, fruit, fallen leaves or petioles depending on host and anthracnose species
    • spores are water- or air-dispersed during leaf expansion, especially during spring rains when temperatures are 50-68 degrees F
    • infected leaves can spread disease to other leaves during rain events throughout the growing season

    IPM Recommendations

    • Manage trees to improve or maintain overall health.
    • Rake and destroy fallen leaves to remove overwintering inoculum.
    • Prune out dead branches or branches with cankers.
    • Water and fertilize as necessary to maintain tree vigor.
    • Apply preventative fungicides before leaf buds open, then every 10 to 14 days until disease conditions become unfavorable.