Question
We live in Central Okla.and have a pink dogwood that seems to be infected with some kind of blight. The top branches have blackened shriveled leaves and the tree leaves appear wilted. What is wrong with the tree?
The tree is in light shade and has been planted for 3 years.

Answer
Sounds like dogwood anthracnose. Leaf symptoms are first noted on newly opened leaves in spring. Three kinds of leaf symptoms may develop: leafspot, blotch, and blight. Leafspots are localized dead or discolored areas scattered in the leaf blade. Blotch refers to irregular dead patches often observed on tips or along leaf margins. Blighting, the death of the entire leaf blade, commonly occurs throughout the canopy of infected dogwoods in shady areas, or within the lower, shaded part of the canopy of those in sun-exposed sites. Blighted leaves become withered and sometimes remain attached to branches throughout the winter. Even bracts can show telltale symptoms of the disease: reddish purple spots or brown blotches.

Twig dieback occurs when infection advances from blighted leaves directly into the stems. Twig death tends to be concentrated in the lower branches of dogwoods, hence the early name of the disease, "lower branch dieback." Epicormic branches (clusters of sprouts) appear on the trunk and main branches following dieback; these are readily infected, and infection spreads from them into the trunk and main branches, where it causes cankering (localized dead areas in the bark and cambium).

An understanding of how environmental conditions affect dogwood anthracnose has helped researchers develop control practices. Sunlight and moisture are the most important influences. Anthracnose is more severe, and tree mortality is greater, on dogwoods in the shade. In full sun, symptoms are more severe in the lower branches than in the upper, exterior canopy, and infected trees often recover with proper maintenance.

Dogwood anthracnose thrives in moist conditions. For dogwoods in the Northeast, leaf symptoms begin to appear following leaf expansion, provided there is enough rainfall to keep the leaves wet for several hours at a time. Foliar infection can recur throughout the summer except during very dry periods. Moisture is also key to the production of fungus spores, which emerge from pinhead-sized fruiting bodies on dead leaf and twig tissues of infected dogwood. Under moist conditions, blighted dogwood leaves that often remain hanging over winter are a source of spores for new infections in the spring.

Control
Cultural. Properly prune out and dispose of infected twigs and attached leaves. Wash shears in soapy water and swab in rubbing alcohol after cutting. Rake up fallen leaves during the growing season and in the fall, and burn them or place them in the garbage. Do not compost them. These procedures should eliminate much of the fungus, but control will probably be incomplete because on most trees it is usually not possible to remove all of the overwintering diseased tissues, and spores can also spread from nearby infected trees.

The eastern flowering dogwood (C. florida), commonly grown in this area as an ornamental, is only moderately susceptible to this disease compared to the highly susceptible native dogwood. Under high disease pressure, however, it will also sustain considerable damage. Kousa dogwoods (C. kousa) have good resistance to this disease and are suggested for planting in this area. Kousa varieties have a wide range of forms and flower habit but will not duplicate the large upright native trees.

Chemical. Several fungicides will control this disease when applied at the proper time and with thorough coverage of leaves and twigs. Banner, Cleary's 3336, Daconil 2787, Fore and Zyban are registered for use by commercial applicators. Homeowners could use a fungicide such as Broad Spectrum Mancozeb Spray, Ortho Multi-Purpose Fungicide, Cooke Daconil, Blackleaf Lawn and Garden Fungicide or Microcop. Sprays should begin at bud break. Follow label directions and precautions. Applications later in the season may be needed if wet weather occurs and there are infected leaves and/or twigs on the trees. These late season sprays will not cure tissues already infected, but are aimed at protecting twigs and buds that will be important for tree growth the following year.

Here is a link to a web site with information on several diseases of dogwood with pictures and the amount of fungicide to use. http://www.aces.edu/pubs/docs/A/ANR-0551/