3.5 (1 = rare 5 = annual)

3-5 (1 = very little damage 5 = plants killed)

Flowering dogwood (Cornus florida) and the Kousa dogwood (Cornus kousa). The fungus is killing tree-type dogwoods in the wild. In the landscape, the disease can be kept in check with fungicides.

Tree

• Flowering Dogwood (Cornus florida)
• Kousa Dogwood (Cornus kousa)

Lower leaves on the tree are the first to be infected. Necrotic (dead) spots are tan to brown with a purplish margin. Leaves die and drop early. Cankers form on twigs and trunk during the spring and fall. Necrotic areas on the twig and trunk discolor. The cankers girdle the twigs and trunk thus cutting off water and nutrients to plant parts beyond the cankered areas. The cut off tissue then dies. It is common for new shoots to sprout below the cankered area on the trunk. These new shoots are very prone to infection. This disease may be confused with spot anthracnose (Elsinoe corni) and Septoria; both of which affect dogwood and are mainly cosmetic.

If rainy weather persists during flowering, the pathogen is known to infect the "flower" (white bracts).

To help reduce infection and increase the plant's resistance, keep plants healthy. Plant the trees in the right location. Then follow good cultural practices during planting, maintenance and pruning of these trees. Effective fungicidal control must be started before there is any major dieback. Prune out and destroy infected branches. Removing and destroying infected leaves may have a limited benefit. Removing the water sprouts helps to reduce trunk cankers. Use recommended fungicides according to directions.

Home, Yard & Garden Pest Guide
The Home, Yard & Garden Pest Guide (C1391) provides is written for homeowners and other residents and provides nonchemical and current chemical recommendations for controlling pests associated with trees, shrubs, turf, flowers, groundcovers, vegetables, fruit, and houses. In addition, you'll find detailed information about integrated pest management, pesticide safety, and pesticide application and calibration techniques. This publication may be purchased at your local University of Illinois Extension Unit office, or by calling 800-345-6087, or by placing an order online (search for "C1391").
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Illinois Commercial Landscape and Turfgrass Pest Management Handbook
The Illinois Commercial Landscape and Turfgrass Pest Management Handbook (ICLT) is written for professional applicators and provides nonchemical and current chemical recommendations as well as application timing information for all major pests of turf, woody ornamentals and herbaceous ornamentals. This publication may be purchased at your local University of Illinois Extension Unit office, or by calling 800-345-6087, or by placing an order online (search for "ICLT").
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U of IL - Distance Diagnosis through Digital Imaging
A free plant, weed, insect and disease identification service available through your local University of Illinois Extension office. Center Educators or State Specialists review & respond to information and digital images submitted by local Extension office personnel. Some samples may require further examination or culture work (nominal fee involved) at the U of IL Plant Clinic.
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U of IL - Plant Clinic
Services include plant and insect identification, diagnosis of disease, insect, weed and chemical injury (chemical injury on field crops only), nematode assays, and help with nutrient related problems, as well as recommendations involving these diagnoses. Microscopic examinations, laboratory culturing, virus assays, and nematode assays are some of the techniques used in the clinic.
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