Ten cultivars of dogwoods (Cornus spp.) were evaluated in multi-year trials for relative reisistance to the dogwood borer, Synanthedon scitula (Harris); cold injury; canker disease, Botryosphaeria dothidea; spot anthracnose, Elsinoe corni; and powdery mildew, Oidium sp., Microsphaera sp., and Phyllactinia sp. Similarly, eight cultivars of birch (Betula spp.) were evaluated for resistance to the birch leafminer, Fenusa pusilla (Lepeletier); Japanese beetle, Popillia japonica Newman; aphids, Hamamelistes spinosus Shimer; the bronze birch borer, Agrilus anxius Gory; and leaf-spot, Cryptocline betularum. All cultivars of C. florida, C. kousa and C. kousa x florida were susceptible to dogwood borer, although the C. florida cultivars were surviving better than the others. Cornus mas and C. kousa cultivars were relatively resistant to powdery mildew while C. florida x kousa hybrids and C. florida ‘Cherokee Brave’ were intermediately resistant. Betula platyphylla szechuanica ‘Purpurea’ was highly susceptible to the bronze birch borer, whereas B. nigra and B. n. ‘Heritage’ were the most susceptible birches to aphid damage. Betula jacquemontii was highly susceptible to Japanese beetle defoliation. Betula pendula, B. nigra, and B. n. ‘Heritage’ were most susceptible to defoliation by birch leaf spot. This study suggests that dogwood and birch cultivars vary in susceptibility to key insect pests and diseases. Planting relatively resistant cultivars may be useful in managing perennial pests in urban landscapes.

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Author notes

This research was supported in part by the nursery industry through contributions to The Horticultural Research Institute, 1250 I Street NW, Suite 500, Washington, DC 20005. We thank Evergreen Nursery Company, Sturgeon Bay, WI, J. Frank Schmidt and Son Nursery, Boring, OR, and Rabbit Run Nursery, Richmond, KY, for donating plants. Jack Doney, David Held, Jason Scanell, Betty Kreuger and Nicole Mason assisted with this project. We extend special thanks to Daniel A. Potter and Ric Bessin for reviewing the manuscript.

2To whom all correspondence should be sent: Monte P. Johnson, USDA/CSREES/PAS, Waterfront Centre, 1400 Independence Ave. SW, Stop 2220, Washington, DC 20250-2220.

3Department of Plant Pathology, University of Kentucky.

4Department of Horticulture, University of Kentucky.