Dogwoods for American Gardens
Total Page：16
File Type：pdf, Size：1020Kb
Agricultural Extension Service The University of Tennessee PB1670 Dogwoods for American Gardens 1 Dogwoods for American Gardens Willard T. Witte, Mark T. Windham, Alan S. Windham, Frank A. Hale, Donna C. Fare and Wayne K. Clatterbuck About the Authors Willard T. Witte, Associate Professor (retired), Dept. of Ornamental Horticulture and Landscape Design, The University of Tennessee Agricultural Experiment Station, Knoxville Mark T. Windham, Professor, Dept. of Entomology and Plant Pathology, The University of Tennessee Agricultural Experiment Station, Knoxville Alan S. Windham, Professor, Dept. of Entomology and Plant Pathology, The University of Tennessee Agricultural Extension Service, Nashville Frank A. Hale, Associate Professor, Dept. of Entomology and Plant Pathology, The University of Tennessee Agricultural Extension Service, Nashville Donna C. Fare, Research Horticulturist, U.S. National Arboretum, Floral & Nursery Plants Research Unit, McMinnville Wayne K. Clatterbuck, Associate Professor, Dept. of Forestry, Wildlife & Fisheries, The University of Tennessee Agricultural Extension Service, Knoxville Acknowledgements The authors acknowledge the contributions of Professors Donald B. Williams, Charles H. Hadden and Harry E. Williams for their original publication entitled “The Flowering Dogwood in Tennessee” (The University of Tennessee Agricultural Extension Service Publication 589, 1969), which was used as a base for this publication. Appreciation is expressed to Hubert P. Conlon, Mark A. Halcomb, Carol J. Reese and Stephen Garton for their peer review of this publication. We also thank Wanda H. Russell for editorial review and Gary R. Dagnan for publication design. Printing of this publication is funded by the USDA Forest Service through a grant with the Na- tional Urban and Community Forestry Advisory Committee. Cover Photo: Wayne K. Clatterbuck 2 Contents Introduction ..................................................................4 Facts and Legend ........................................................5 Kinds of Dogwood ......................................................5 Cultivars of Flowering Dogwood....................8 Cultivars of Kousa Dogwood ........................13 Cultivars of Pacific Dogwood........................16 Interspecific Hybrid Dogwoods.....................16 How to Grow the Flowering Dogwood ................17 Soil ..................................................................17 When to Plant................................................17 How to Plant..................................................18 Care After Transplanting .............................19 Fertilizing.......................................................19 Mulching.........................................................19 Watering .........................................................20 Pruning...........................................................20 Will My Dogwood Bloom?.............................20 Integrated Management of Insects and Diseases of Flowering Dogwood ...........................21 Insects.............................................................21 Dogwood Borer.........................................21 Asian Ambrosia Beetle ...........................22 Dogwood Club Gall..................................23 Dogwood Twig Borer...............................23 Dogwood Sawfly.......................................23 Rose Leafhopper.......................................24 Cottony Maple Scale................................24 Walnut Scale ............................................24 Two-spotted Spider Mite .........................25 Diseases..........................................................25 Spot Anthracnose.....................................26 Dogwood Anthracnose.............................26 Dogwood Canker......................................27 Phytophthora Root Rot ............................27 Powdery Mildew.......................................28 Other Dogwood Diseases.........................28 Leaf Scorch...............................................29 Summary ...................................................................29 General Disease Management for Dogwoods Growing in Landscapes ......................29 Key to Diseases of the Flowering Dogwood ......30 Selected References ..................................................31 Credit: Wayne K. Clatterbuck Web Sites The University of Tennessee Dogwood Research Group maintains a Web site (dogwood.ag.utk.edu) that is devoted to cultivation and growth of flowering dogwoods. The site contains descriptions and photographs of Cornus species, dogwood cultivars, diseases and insect pests. The site is kept up to date concerning new disease epidemics and outbreaks of insect pests, has a FAQ (Frequently Asked Questions) section and maintains a forum where individuals can ask/or discuss problems they are having with their dogwoods. A series of publications about site and tree selection, tree maintenance and tree care for urban landscapes are available at The University of Tennessee Agricultural Extension Service Web site (www.utextension.utk.edu/publication/forestry.htm). 3 Dogwoods for American Gardens Introduction Seventeen species of dog- wood are native to the United States, with about 50 through- out the northern hemisphere of the world. The familiar species we call “flowering dogwood,” Cornus florida , is related to many others. This publication discusses those of ornamental value. Most dogwood species are either shrubs or small trees and can be easily divided into two main groups: those with red fruit (occasionally yellow) and those with blue-black (some- times whitish) fruit. Red fruit of . Credit: Mark T. Windham Most of the red-fruited species have large showy bracts Modern selections grown by horizontal gray branches surrounding a terminal cluster nurseries have been chosen for tipped with upturned, button- of tiny true flowers. These large- large, white, clear pink or dark like flower buds. bracted dogwood species are all red bracts; variegated leaves; In addition to its beauty, trees, except for the bunchberry, double bracts; weeping or dwarf the dogwood is an important a low-growing ground cover growth habit and other special food source for birds and wild- found in northern climates. Most characteristics. life. Berries of the flowering of the blue-fruited species are The beauty of flowering dogwood are eaten by many shrubs and all have whitish, dogwood is not limited to a species of songbirds and small flat-topped flowers of tiny particular season or a single mammals from August until clusters called cymes or umbels. part of the tree. Most selections they are gone, often as late as These flowers are without the begin with a glorious floral February or March. showy bracts. display in April, followed by This publication provides The native flowering attractive green foliage arrayed cultural information and dogwood, Cornus florida , is one on horizontally spreading ornamental characteristics to of the most beautiful small trees branches. A show of bright red help you select dogwoods for in the world, with ornamental berries appears in late summer your landscape and how to value in all seasons. Nearly all and is accompanied by early maintain them in good health. flowering dogwoods in the wild development of dark red foliage. If you have any questions, have white bracts, but a rare The beauty cycle ends with an contact your Cooperative pink form does occur naturally. interesting winter silhouette of Extension Service. 4 Facts and Legend have been associated with Jesus’s Cornus nuttallii, in Clatskanie, The name dogwood appar- blood on Calvary. The dogwood OR that is 60 feet tall with a ently originated in Europe. The also served in the field of medi- 58-foot branch spread and a bark of one of the European cine at one time. Dogwood bark trunk diameter of more than 3 species was boiled in water and was one of many barks used as a feet. The largest flowering used for washing dogs suffering fever medicine before quinine dogwood is in Sampson County, from mange. Most authorities came into general use. NC and is 31 feet tall with a 48- believe that dogwood is a corrup- Of more importance is the foot branch spread and a trunk tion of dagwood, with dag being role the dogwood once played in diameter of just greater than 3 an old name for a meat skewer. the textile industry and in feet. Champion trees often do The hard wood of this species is sports. The wood from dogwood not retain their title long due to useful for that purpose. was used to make shuttles for loss of branches from disease or The name dogwood is less weaving machines because of its storms or from being outgrown inspirational than the legend very heavy, fine-grained and by competitors. that the dogwood once grew as a very hard properties, and because tall, straight tree and was used with wear it becomes extremely Kinds of Dogwood for timber. But when the wood smooth and resistant to abrasion. Dogwoods are in the genus was used to make the cross of The same qualities made it Cornus within the Cornaceae Calvary, Jesus was so moved useful for golf clubs, jeweler’s family. The most common orna- that he promised the tree would benches and as wedges for mental and native species of never again grow large enough splitting logs. Cornus are described in this to be employed for such a pur- Given time and favorable section. Those native to the pose. It is also said that the growing conditions, some dog- United States are marked with a bracts of the dogwood