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IPM Scouting in Woody Landscape Plants

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Dogwood anthracnose
IPM scouting in woody landscape plants > dogwood anthracnose
Cause: Discula destructiva (fungus)

Hosts: Flowering dogwood (Cornus florida) may be killed by this pathogen; Kousa dogwood (Cornus kousa) can serve as a carrier but rarely develops severe symptoms. Other dogwoods growing in Michigan are not affected.

Symptoms: Tan spots, sometimes with purple margins, appear on leaves and necrotic areas on leaf margins or veins. Lower leaves are affected first. Infected leaves may persist on the tree in the fall.
Dogwood anthracnose
How it’s spread: Cool, wet weather in the spring or fall favors the development of this fungal disease. Spores produced from fruiting bodies on infected leaves and twigs spread by splashing rain to healthy tissue and nearby trees. Extensive twig dieback leads to the development of watersprouts. Infected watersprouts allow the fungus to spread into the main trunk and branches. The cankers eventually girdle the tree and kill it.

Management: There is no natural resistance to this disease. Avoid planting imported dogwoods near native dogwood stands. Although not all imported dogwoods are infected, early infections are difficult to detect and the disease is hard to manage once it spreads into a forest. Sanitation, i.e. pruning off and destroying dead twigs, removing watersprouts, and raking up fallen leaves is important. Plant trees in sunny exposures with good air circulation to allow quick drying of foliage. Avoid heavy applications of nitrogen fertilizers that encourage succulent growth. Maintain tree vigor through mulching and watering during dry periods.
Infected twig Extensive twig dieback
Twig of flowering dogwood infected with dogwood anthracnose fungus. Raised, brown spots are fruiting bodies (acervuli) containing the spores and can be seen with a hand lens. Look at the second node back from the tip on the smallest terminal twigs for the fruiting bodies. Extensive twig dieback leads to formation of epicormic shoots.

Additional information

This information was developed from A Pocket IPM Scouting Guide for Woody Landscape Plants by Diane Brown-Rytlewski. Purchase this in a pocket-sized guide for reference in the orchard from MSU Extension (publication E-2839).
The MSU IPM Program maintains this site as an access point to pest management information at MSU. The IPM Program is administered within the Department of Entomology, fueled by research from the Michigan Agricultural Experiment Station, delivered to citizens through MSU Extension, and proud to be a part of Project GREEEN.
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Updated 7/12/07