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Agricultural Extension Service The University of PB1670 Dogwoods for American

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 and Design, The University of Tennessee Agricultural Experiment Station, Knoxville

Mark T. Windham, Professor, Dept. of Entomology and 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 , Floral & Nursery 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 of Flowering Dogwood...... 8 Cultivars of Kousa Dogwood ...... 13 Cultivars of Pacific Dogwood...... 16 Interspecific 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 and Diseases of Flowering Dogwood ...... 21 Insects...... 21 Dogwood Borer...... 21 Asian Ambrosia ...... 22 Dogwood Club Gall...... 23 Dogwood Twig Borer...... 23 Dogwood Sawfly...... 23 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 Root Rot ...... 27 ...... 28 Other Dogwood Diseases...... 28 Scorch...... 29 Summary ...... 29 General Disease Management for Dogwoods Growing in ...... 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 , dogwood cultivars, diseases and 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 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- are native to the , with about 50 through- out the northern hemisphere of the world. The familiar species we call “flowering dogwood,” Cornus , is related to many others. This publication discusses those of ornamental value. Most dogwood species are either or small and can be easily divided into two main groups: those with (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 Modern selections grown by horizontal gray branches surrounding a terminal cluster nurseries have been chosen for tipped with upturned, button- of tiny true . These large- large, white, clear pink or dark like buds. bracted dogwood species are all red bracts; variegated ; 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 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 . 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, , 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 ’s , 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 was used to make the cross of The same qualities made it Cornus within the Calvary, Jesus was so moved useful for golf clubs, jeweler’s . 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 are set in attain large stature. single asterisk (*). Hardiness is the shape of a cross and bear Currently, the largest known indicated by the USDA plant nail marks of the , dogwood tree in the United (Figure 1). and the red leaves in autumn States is a Pacific dogwood,

Average Annual Minimum Temperature

Temperature (°C) Temperature (°F) -45.6 and Below Below -50 -42.8 to -45.5 -45 to -50 -40.0 to -42.7 -40 to -45 -37.3 to -40.0 -35 to -40 -34.5 to -37.2 -30 to -35 -31.7 to -34.4 -25 to -30 -20.9 to -31.6 -20 to -25 -26.2 to -28.8 -15 to -20 -23.4 to -26.1 -10 to -15 -20.6 to -23.3 -5 to -10 -17.8 to -20.5 0 to -5 -15.0 to -17.7 5 to 0 -12.3 to -15.0 10 to 5 -9.5 to -12.2 15 to 10 -6.7 to -9.4 20 to 15 -3.9 to -6.6 25 to 20 -1.2 to -3.8 30 to 25 1.6 to -1.1 35 to 30 4.4 to 1.7 40 to 35 4.5 and Above 40 and Above

Figure 1. USDA Plant Hardiness Zone Map Credit: USDA-Agricultural Research Service

5 *Cornus florida, Flowering Dogwood. becoming more experienced with Pacific dogwood and flowering Zones 5-9. Native to the Eastern growing kousa dogwoods, and better dogwood are known. United States from the Gulf of types are being evaluated. and central Florida to east , Cornelian Cherry. , and to *Cornus nuttallii, Pacific Dogwood. Zones 5-8. A hardy European species Chicago and southern New . Zones 6b-9a. The native range is a that seems to be at the southern Typically grows 12-20 feet tall with a broad band along the West Coast limit of its heat tolerance in the mid- 6-12 inch trunk diameter, but from about San Francisco, excluding South, where it frequently presents a sometimes larger. Considered a short- the Imperial Valley, northward into poor appearance by the end of to medium-lived tree in landscapes, . Grows taller and summer. It grows as a small tree or but may live 100 on good sites. more upright than flowering multi-stemmed up to 15-20 Blooms in mid-spring as leaf buds dogwood. Blooms are also larger and feet tall. Cornelian cherry blooms in break. Four showy bracts, notched at typically have six bracts (un-notched) very early spring, before , the tip, rapidly expand and turn instead of four. May re-bloom in late with many clusters of small, yellow, white, centered by a cluster of 20 or summer. Flower bud scales (bracts) bractless flowers. The oblong cherry- more tiny true flowers with four do not enclose the over-wintering like fruit is both ornamental and , four and one stigma. flower cluster. Bark remains smooth. edible and may be used for Scarlet oblong-oval berries in the fall Unfortunately, it does not seem to preserves. A few cultivars are are valued food for birds and wildlife. thrive in the East. Hybrids between available in the trade. A few yellow-fruited forms occur. The distinctive “alligator” bark is broken into small squarish blocks. Buttonlike flower buds occur on upturned horizontal branches in winter. There are many selections and cultivars chosen for superb ornamental characteristics.

Cornus kousa, Japanese or Chinese or Kousa Dogwood. Zones 4-8. Native to , and , this tree will grow in the U.S. wherever our native flowering dogwood grows. Blooms have four-pointed flower bracts about as large as those of flowering dogwood, but appear a few weeks later. The foliage develops before the bracts appear. The long-lasting bracts are displayed above the leaves on long flower stems. The aggregate fruit looks like a rosy-red golf ball, the size , Pacific Dogwood. Credit: Mark T. Windham of a nickel or larger, and contains several embedded in pulpy flesh. The pulp is said to be edible when ripe. As gain in weight and size, they hang under the branches on long stalks like ornaments. Borers or diseases rarely trouble kousa dogwoods. The average kousa dogwood tree has to be a few years older than comparable flowering dogwoods to develop a heavy bloom display. Some mature kousa trees have beautiful flaking mottled bark patterns on a smooth trunk. The flower bracts of some kousa dogwoods may become tinted with pink when the plant experiences cool weather, is under stress or when the bracts age. Varieties are currently being selected that are considered truly pink flowering. Nursery producers are 'Aurea', Cornelian Cherry. Credit: Willard T. Witte

6 , Japanese Cornel. *, Gray Dogwood. Zones 5-8. This shrub or tree is very Zones 4-8. A shrubby tree to 15 feet, similar to Cornelian cherry, but found on moist sites from to grows larger (to 30 feet), and has the , south to Florida, and west added attraction of interesting to and Oklahoma. It tends exfoliating bark that flakes off to to grow in colonies due to a create gray, brown and orange suckering habit, so it is often better patches on mature trunks. Flowers suited for wildlife and native plant are similar to Cornelian cherry but gardens than well-groomed bloom a week earlier, well before the landscapes. White flower panicles in leaves emerge. The edible but mid-spring are followed briefly by flavorless scarlet berries ripen after white berries. Red fruit stalks Cornelian cherry. remain ornamentally interesting until fall. A recent selection is * (formerly C. named 'Jade'. stolonifera), Red Osier Dogwood. Zones 2-7. Native stands grow in moist-to- *, Silky Dogwood. wet sites from Newfoundland to Zones 5-8. This shrub ranges from Manitoba, south to and Maine to , south to , west to , but have and Florida, and grows to 9 feet. a wider adaptability in landscapes. White flower clusters form a flat- This multi-stemmed shrub grows to 7 topped cyme that blooms in early Red twigs on , Red Ozier Dogwood. Credit: Willard T. Witte feet and spreads slowly by summer, followed by blue berries. underground stems, making thickets. While considered too coarse and Flat clusters of chalky white flowers straggling for most gardens, in the form a cyme that blooms in late proper setting it has a place, as in a spring, often followed by white berries. native plant or wildlife garden. Varieties are available with bright red, olive-yellow or green stems for winter , Giant Dogwood. color. 'Silver and Gold' has white Zones 4b-8. Native to China and variegated leaves and yellow stems. Japan, this is the largest and fastest Again, these plants are grown for growing of the dogwoods, capable of winter bark color and old branches attaining 60 feet. Giant dogwood should be pruned to the ground every develops distinctly spreading or two to induce a good growth of horizontal branches at an early age. new, brightly colored branches. Creamy white flower clusters form a 3-7 inch flat-topped cyme in early *, Pagoda summer that are showy and may be Dogwood. Zones 3-7. This small, followed by bluish-black berries. The widespreading tree is native from large paired leaves may turn reddish to , south or purplish in autumn. It is rare to Georgia and , and west outside of . A beautiful to Missouri and Arkansas. Pagoda variegated form exists. dogwood has a strongly horizontally branching habit and reaches about , Tatarian Dogwood. half the size of flowering dogwood. Zones 2-7. The native range is , Pagoda Dogwood. Yellowish-white flowers in an though northern China to Korea. This Credit: Willard T. Witte upright cyme bloom in mid- to late large shrub, multi-stemmed to the spring and are very fragrant. These base, grows to 9 feet unless cut back. are followed by fruit that changes Since it is grown primarily for the from green to red to blue-black, on winter display of bright coral-red red stalks. Unlike most dogwoods, stems, which is brightest on new this species has alternate leaves growth, the old dull branches should instead of opposite, though this may be cut every spring to ground level be hard to see because leaves tend before growth starts. This also keeps to be clustered near the tips of the plants to a manageable size. Tatarian branches. A rare white variegated dogwood has yellowish-white flowers 1 form, 'Argentea', has smaller in 1 /2 to 2-inch cyme with flat-topped leaves. An antique common name clusters in late spring, often followed was pigeonberry, apparently by white berries. Several varieties Foliage of 'Variegata' or bestowed during the era of the have variegated foliage. 'Argenteo- “wedding cake tree.” . marginata' has an irregular creamy- Credit: Willard T. Witte

7 berries are quite similar to flowering The word '' is a dogwood. Bunchberry grows from horticultural term for 'cultivated , Canada and and variety,' as distinguished from a can sometimes be found at high botanical variety ('varietas') or form elevations as far south as West ('forma') that occur naturally in the Virginia. A challenging groundcover wild. A cultivar name should always plant for garden experts, it requires be enclosed in single quotation shade, moisture, an organic soil and marks. The next section contains cool temperatures. capsule descriptions of the most important and available cultivars for , Bigleaf several species. Dogwood. Zones 5-7. Rare in the U.S., this small tree ranges from the to China and Japan. The tree grows to 35 feet, with large Cultivars of Flowering leaves 4-7 inches long. Flowers are Dogwood, White fruit on yellowish-white in 4-6 inch loose Cornus florida Dogwood. Credit: Willard T. Witte panicles in late summer followed by bluish-purple berries. This species is Several botanical varieties and virtually unknown outside of forms of flowering dogwood have arboretums in this country. been grown in gardens over the years; more than 80 cultivars have been developed from either or *Cornus baileyi, Bailey dogwood, is a non-stoloniferous cousin of red sports (mutations). Newer cultivars osier dogwood and occurs in the continue to be developed. Selections same range. The other main have been made for pink or red difference is a distinctly wooly color, ability to bloom at a young pubescence of young shoots and the age, large bract size, variegated undersides of leaves. Some foliage, weeping or dwarf habit of growth and disease resistance. Bailey Dogwood. botanists ascribe it to be a of C. sericea. Pink and Red Flowering white margin around a leaf center of , Walter dogwood, is Dogwoods: The first record of a subdued grayish-green. On hardy to zone 5 and is native to pink flowering dogwood in the wild 'Gouchaltii' and 'Spaethii' the central China and Korea. It has a was by Mark Catesby of Virginia in marginal leaf variegation is yellow. tree type stature, growing to 30-40 1731. Occasional finds of wild pink Either can add a nice spot of light feet high and wide with the dogwood still occur to this day. color to a summer garden. Some “alligator” bark typical of our native Most pink and red dogwood will not afternoon shade is beneficial. flowering dogwood. The 2-3 inch flat come true from seed and are cyme is formed by white flower usually propagated by bud . , Bloodtwig clusters in mid-summer, followed by Unnamed selections are often Dogwood, is a European cousin of small black berries that mature in marketed under the name 'Rubra', Tatarian dogwood. The rough- early fall. This species deserves wider which seems to be applied to any looking, suckering shrub is rarely testing and use. pink type not identified as a recommended for ornamental use specific variety. Most pink and red other than for its purplish-red winter Botanical manuals describe many cultivars are not as winter hardy twig color. more species of native and exotic as most white cultivars, nor are dogwoods, but most are of lesser they as heat tolerant, except for a few selections originating in the *, Pale Dogwood, and ornamental value than those described . New foliage often *, Roughleaf above or are of only local interest. Dogwood, are shrubby cousins of silky From the species of Cornus comes out in the spring with a dogwood and occur in roughly the mentioned above, one can see that distinct red tinge, and usually develops brilliant red fall color. same range and habitats. They differ the native flowering dogwood is just in minor botanical characters such as one member of a large and diverse : Variegation is twig color, pith color and hairiness genus. It is the dogwood of interest Variegated Foliage (pubescence) of the leaves. to most gardeners, and is expressed when mutations occur that unquestionably beautiful, a small block development of chlorophyll in one or more layers of leaf tissue. In *, Bunchberry. tree for all seasons. However, many Zones 2-6a. This subshrub (to 9 of the other species and their these cases, the variegated part is usually cream, yellow or golden due inches tall) spreads by woody cultivars have special ornamental to the xanthophylls and carotenes forming a ground cover in merit of their own and can add to still in the tissue. If formation of the woods. The white bracts and red the diversity of our landscapes.

8 yellow pigment is also blocked, blasted by killing frosts, and not go mildew. Red blooms have a paler variegation will be white. Since dormant soon enough in the fall to center. New growth with reddish several layers of leaf tissue may be survive killing fall frosts. Northern leaves turning green at maturity. affected independently of each other, ecotypes grown in the deep South may it is possible to have multicolor not grow and bloom well and may 'Cherokee Chief'. Considered as one variegations, expressed as central suffer from heat stress. These factors of the best red-flowering dogwoods blotches, marginal bands or irregular are obviously more critical at the on the market today. Deep rose-red splashes along leaf veins. extreme southern and northern limits blooms and reddish leaves on new Many variegated cultivars of the range where flowering dogwood growth. Vigorous grower with central maintain their showy leaf can be grown. Also in the north, leaf leader and uniform branching. variegation pattern longer into buds may be winter-hardy while summertime when grown in full sun. flower buds may be damaged from 'Cherokee Daybreak'. Improved In the shade, green pigment may severe cold, so good flower bud white-flowered variegated selection eventually develop throughout the hardiness is sought in northern resists scorch in full sun. Leaves have leaf blade, resulting in fading of the cultivars. Listed below are capsule a blotched green and gray-green variegation pattern. Because descriptions of some of the more center with a wide irregular margin variegated-leaved plants have less important modern cultivars of of creamy white that turns pink in chlorophyll, they grow slower and set flowering dogwood in the nursery cooler fall weather. White bracts. fewer flower buds than green-leaved trade, parks and arboreta. Susceptible to powdery mildew. plants. White sectors of variegation are more susceptible to leaf scorch 'Appalachian Spring'. This new 'Cherokee Princess'. Selected in when plants are stressed than yellow cultivar is the only flowering Mayfield, KY for its large white or pale green sectors. Variegated dogwood that is resistant to dogwood blooms exceeding 4 inches in parts of leaves are the first to show anthracnose ( destructiva). It diameter. Very floriferous and blooms fall color, as the developing has apple green leaves about one at an early age. Highly resistant to anthocyanin pigments are not third larger than the species, and spot anthracnose. masked by chlorophyll. Many types sculpturally curving white bracts, of leaf variegation tend to be followed by the typical red berries. unstable and one or more shoots Red to purple fall color. occasionally revert to all green. Unfortunately, this cultivar is Green shoots are more vigorous and susceptible to powdery mildew. must be immediately and entirely pruned or they will overgrow and 'Autumn Gold'. White bracts. crowd out the desired variegated Recent introduction from Winchester, part of the plant. TN with conspicuously golden fall and winter bark color. Novelties and Special Characteristics: Some flowering 'Cherokee Brave'. A recent dogwood cultivars are grown for the introduction from Winchester, TN 'Cherokee Brave'. unusual habit of growth (dwarf, with good resistance to powdery Credit: Willard T. Witte weeping, fastigiate or columnar), leaf shape (willowleaf), yellow berries, double flowers, fragrance or larger than normal berries or flowers. These novelties add interesting accents to many landscapes.

Southern vs. Northern Origin: Many selections found in the wild have been propagated and brought into cultivation. In the capsule descriptions below, the origin is noted when known. The origin is important because flowering dogwood is closely adapted to its ecological niche, especially in regard to winter hardiness, bloom time in the spring and acclimating for winter dormancy in the fall. A southern ecotype grown in the north may winterkill due to lack of hardiness, bloom too early in the spring and thus have flowers 'Cherokee Princess'. Credit: Willard T. Witte

9 been going on for almost a century. Then Dr. Elwin Orton of Rutgers University in began working with dogwood in his ornamental plant-breeding program. In the early 1990s, he patented and released the Stellar series, which are hybrids between Cornus florida and . With one exception ('Ruth Ellen'), these have astronomy-based names such as 'Aurora', 'Constellation', 'Stellar Pink', etc. Dr. Orton has also made crosses with Cornus nuttalli, and some of the resulting progeny are out on trial prior to naming and release. Dr. Orton also bred and patented an unusually vigorous Cornus florida with fruit nearly twice normal size and named it 'Wonderberry'. According to the most recent Researchers at The University of Tennessee estimates, there are about 80 cul- Institute of Agriculture (UTIA) began searching for tivars of the flowering dogwood, disease-resistant flowering dogwoods in the early Cornus florida, that have been 1990s. They discovered several in the wild and UTIA named. This partly reflects the propagated them for further testing. One, named and many decades that nursery pro- released as 'Appalachian Spring', is highly resistant ducers have been growing this species. Some of the to dogwood anthracnose. It is currently being increased older cultivars, while documented in the horticultural and should be on the market by 2005. Then in the literature, may no longer exist; that is, they have not mid 1990s, an epidemic of powdery mildew severely been perpetuated in nursery production and have died impacted dogwood seedlings in nurseries all over the out of landscapes. eastern United States. UTIA scientists searched There are about 70 cultivars of Cornus kousa, the nursery fields for resistant seedlings and rescued about Chinese dogwood. Many of these are of recent origin, 80. After extensive testing, three of these are being owing to a surge of interest in this species. Many newer named and patented: 'Jean’s Appalachian Snow', Chinese dogwood cultivars have yet to be tested for 'Karen’s Appalachian Mist' and 'Kay’s Appalachian adaptation and performance over a wide range of Blush'. They are being increased and should be climates and sites, but some are destined to add new available for purchase by 2007. interest to our gardens. UTIA researchers currently have a dogwood- Until recently, nearly all dogwood cultivars came breeding program aimed at combining resistance to the to be named because someone noticed something two diseases (anthracnose and powdery mildew) in new different and worthwhile about a particular individual plants. They have even worked out methods to employ dogwood seedling and then decided to propagate it and honeybees, which normally do not visit dogwood flowers, name it. Since dogwood is an obligate outcrosser (it to achieve cross-. Hundreds of seedlings have does not pollinate its own flowers), there is always some been produced and are being tested, and breeding genetic variability existing in every new crop of seed. orchards of dogwood have been planted to produce seed. Plant enough seed from enough different sources and The same UTIA scientists are screening Cornus some of the possibilities will be expressed in a few of kousa seedlings for heat and drought tolerance. A the seedlings, such as a dwarf or weeping or fastigiate number of these seedlings have been selected and are (columnar) habit of growth, bract color, bark color, being placed in an evaluation program. variegated foliage of several different patterns, ability to bloom at an early age, insect or disease resistance and so on. Dogwoods may also change because of the expression of somatic mutations, which is a random change in a gene that may occur once in every several million cell divisions. For example, if a mutation occurs that affects the formation of chlorophyll, and this mutation just happens to be located in a layer of leaf tissue of an expanding bud or shoot, then it is possible that a bud sport or branch sport might arise with variegated leaves on a tree that otherwise has all green foliage. This does not happen very often, but on a nursery with hundreds of thousands of dogwoods in production, it will likely occur. It takes an alert eye to pick out mutations and a wise nursery producer will offer a bounty to workers who identify one. Up until the last decade, there was no purposeful 'Appalachian Spring' is a flowering dogwood cultivar that is resistant breeding of dogwood to produce new cultivars, unlike to dogwood anthracnose. field and forage crops where breeding programs have Credit: Mark T. Windham

10 'Cherokee Sunset'. Good red bracts and strongly variegated foliage. Leaves have a broad irregular yellow margin that resists scorch in summer heat. Fall color ranges from pink on the margins through red and purple centers. Resistant to spot anthracnose. This unique dogwood was considered stable enough for introduction in 1979, eight years after discovery.

'Cloud 9'. Introduced from Chase, AL in 1951. Wide, overlapping white bracts in profusion. Blooms at an early age. Due to heavy flowering and fruiting, it is slower growing than most dogwoods. A very similar cultivar, 'Barton', selected in 1956 in Birmingham, AL became mixed with 'Cloud 9' in the trade and DNA fingerprinting shows 'Cherokee Sunset' (left) and 'Cherokee Daybreak' (right) plants currently offered under either Credit: Willard T. Witte name are the same.

'First Lady'. Introduced from Hohman, founder of the Kingsville McMinnville, TN in 1969. This Nursery in . variegated cultivar has white blooms, but is not a heavy bloomer. The leaves Howell Hybrids. Not a cultivar have yellow variegations splashed over name, but refers to a group of about a light and dark green background. It 10 numbered seedlings grown by tends to scorch less than plants with Howell Nursery, Sweetwater, TN white variegations. Leaves may turn prior to 1960, from a supposed cross all-green in summer if grown in too of a pink tree from the North and a much shade. It is highly resistant to pink tree from the South ('Prosser'). Seedling #1 became 'Cherokee Chief' 'First Lady'. spot anthracnose. A less vigorous Credit: Willard T. Witte cultivar, but a beautiful specimen and #2 or #3 became 'Sweetwater when well cared for. Red'. 'Cherokee Brave' is assumed to be a seedling of 'Cherokee Chief'. developed by the Tennessee Agricultural Experiment Station. 'Fragrant Cloud'. Introduced from Creamy white bracts that slightly Gatlinburg, TN in 1968. Said to have 'Jean’s Appalachian Snow'. A overlap. Cleft at the tip of the bract a profusion of white flowers and a new, powdery mildew-resistant is flat and deeply pigmented. Red slightly fragrant scent like gardenia. cultivar developed by the Tennessee berries; good autumn color. This vigorous grower is seldom Agricultural Experiment Station. offered. Resistant to spot anthracnose. Very large, pure white, blocky bracts, similar in size to 'Cherokee 'Mystery'. Introduced from Winchester, TN in 1965. This 'Green Glow'. PP#4444. Introduced Princess', are overlapping. Even the dwarfish compact tree has blooms from Portland, OR in 1973. This is a indented cleft at the tip of the bract with large white bracts, but mutation of 'Welchii' with a slight lacks pigmentation. Red berries; occasionally some bracts develop golden vein centered in dark green good fall color. pink blushes or reddish blotches. leaves. Upright growth habit. Rare. 'Karen’s Appalachian Blush'. A Drought-tolerant. Rare. 'Golden Nugget'. Introduced from new, powdery mildew-resistant 'Ozark Spring'. White-flowered Winchester, TN. Similar to 'First cultivar developed by the Tennessee cultivar introduced in for Lady' and 'Hohman’s Golden', this Agricultural Experiment Station. better flower bud hardiness. White white-bracted cultivar has yellow leaf The bracts are long and floppy, bracts and wine-red fall color. margins and tends to turn all green delicate in appearance, and do not Selected from among 125 plants in the shade. overlap. Bracts are white with a pale pink blush developing on the grown from seed collected in Crookston Hill region of Oklahoma. 'Hohman’s Golden'. Introduced margins. Red berries; good fall color. Has flowered after sustaining from Wayne, NJ in 1964. Green and temperatures of –30 degrees F. yellow variegated foliage and white 'Kay’s Appalachian Mist'. A new, blooms. Named after Henry J. powdery mildew-resistant cultivar

11 'Pendula'. Weeping form with drooping bracts and white flowers. May come true to type from seed. Original clone, found wild in Maryland, was raised in a Philadelphia nursery before 1880. Not a particularly attractive weeping tree. There may be several weeping forms in the trade under this name.

'Pink Sachet'. Similar to 'Cherokee Chief' but with pronounced flower fragrance. Assumed to be a seedling of 'Cherokee Chief'. Uncommon.

'Plena'. An older, white-bracted cultivar with semi-double flowers of medium size. Blooms about two weeks later than single-flowered types, thus escaping late spring frost damage. Blooms last longer than 'Rubra'. Credit: Willard T. Witte single-flowered dogwoods, which tend to drop bracts as soon as berries set. Does not set fruit. Very prolific bloom, but visual impact reduced as some flowers hidden by developing 'Pygmy'. A slow-growing plant, 'Rubra'. First described as a foliage. Appears to be immune to reaching perhaps 4 feet in eight botanical variety in 1770. Later, spot anthracnose. years, which generally produces an properly classified as a forma in 1 abundance of small, 1 /2 -inch 1915. This name is not valid at the 'Pluribracteata'. A “double” form flowers. Uncommon. cultivar level, but represents with 7-8 and often more large bracts botanical forms with washed out and true flowers more or less 'Rainbow'. White flowers, and the pink to dark red flowers on different aborted. Blooms 7-10 days later than most brilliant variegated foliage trees. First discovered in Virginia, most other flowering dogwood imaginable under protected but occurs more widely, though cultivars, thus escaping spring frost conditions. Bright deep yellow and infrequently, in the wild. It is a damage. Does not set fruit. Some green leaves in spring and summer beautiful plant when properly grown. authorities lump 'Plena' under this turning to pink, red and blue- The flowers are not as cold hardy or name. There may be several double- lavender in fall. Red berries. Leaves as heat tolerant as the white form. flowering forms. have a wide, irregular, creamy Tends to open a few days later than yellow margin and a green center. typical white form. 'Poinsett'. Golden yellow berries in The lighter margin overlays portions the center of a group of red autumn of the green tissue extending to the 'Salicifolia'. A small, rounded tree; leaves are said to resemble a center of the midrib, creating yellow- the leaves are very narrow and poinsettia. Compact and vigorous green splotches. Subject to scorch in willow-shaped. It has a fine texture growth with long, pointed leaves. exposed sunny sites. and does not flower well.

'Prosser'. Of historical significance 'Red Beauty'. A semidwarf compact 'Spring Song'. A northern type of as the progenitor of most of our tree with many small red blooms. 'Rubra' with especially large flowers current red-flowered dogwood Flowers at an early age. From a of rich, rosy red. cultivars. Found by Bruce Howell, controlled cross in the Rutgers Knoxville, TN around 1920, on University, NJ breeding program. 'Springtime'. The original tree was property owned by Brown Prosser selected from a planting in Spring about three miles from Howell 'Robert’s Pink'. Apparently a choice Grove Cemetery, Cincinnati, in Nursery. Poor growth habit. Flowers pink-flowering dogwood originating 1957. Large, white, overlapping have a good dark red color but in southern in the early bracts, 5 inches across from tip to inferior conformation. New leaves 1900s. A vigorous-growing, pink tip. Wide-spreading growth habit; dark reddish green. dogwood adapted to the Deep South. undersides of the leaves turn a distinctive purplish color in the fall. 'Purple Glory'. New foliage maroon 'Royal Red'. New foliage opens Highly resistant to spot anthracnose. to purple suffused over a light green blood red, then becomes greenish and background. Flower bracts dark red. turns bright red in fall. Flowers are 'Sterling Silver'. An excellent white Susceptible to dogwood canker. deep red and very large. Uncommon. variegated dogwood that does not

12 burn in full sun. Slower growing attractive small-flowered form that or in Zone 6. Narrow than normal, developing a layered tends to have sparse bloom. glossy leaves droop distinctly in effect as it ages. Resistant to spot anthracnose. Holds fall and winter. Purple to wine its color in the Deep South. Requires winter foliage color. This recent 'Stokes Pink'. Pink bracts on a less chilling than other dogwoods to introduction from China may be medium-size, vigorous, upright tree. break winter dormancy. Vigorous elevated to species rank by Good in warm climates. grower with red coloring of new botanists. Winter hardiness growth. Blooms late in season. unknown, but probably less than 'Sweetwater Red'. Selected in most C. kousa. Definitely 1954 by Howell Nursery, Knoxville, 'Wonderberry'. Unusually vigorous, recommended for trial in climates TN and introduced in 1961. Deep dark green leathery leaves, brilliant previously considered too warm for red flowers and reddish foliage, red tubular fruit about twice-normal good performance of most kousas. good red-purple fall color, and size, and abundant white flowers in Blooms later than most C. kousa. moderately disease resistant. See early spring. From a controlled cross Howell Hybrid listing. of the breeding program at Rutgers 'Autumn Rose'. Long, drooping, University, NJ. wavy (almost ruffled) leaves 'Weaver'. A 1941 Florida selection present a different, yet distinctive with stronger and larger bronzy ‘World’s Fair'. Large white bracts. appearance. A small upright tree new foliage, and larger and more Blooms at an early age, stocky selected for its unusual creamy, numerous blooms. Well-suited for trunk, large-diameter limbs, drought pale greenish-white bracts in early Florida, as it does not require as resistant, hardy to –7 degrees F. summer. Fall color ranges from long a period of chilling to pink to light red. Sparse production overcome winter dormancy as more 'Xanthocarpa'. White blooms and of fruit. northern ecotypes. yellow fruit. Botanically this is a forma of the species. Since more 'Beni Fuji'. Small, vase-shaped tree 'Welch Bay Beauty'. Particularly than one genotype has been placed with a multitude of small, starry- handsome double form with flowers under this forma, the name is pink bracts. Slightly distorted like gardenia, seven sets of whorled invalid at the cultivar level. Several leaves smaller than normal, reddish white bracts 4.5 to 5.5 inches in clones are in cultivation (see new growth. diameter. Lower bracts shed before 'Poinsett'). Stems show no trace of those above. Trees bloom at an early red pigment, being devoid of 'Big Apple'. Large spreading tree age and blooms last longer than most anthocyanin pigments. with heavy-textured dark green dogwoods. Found in the wild in leaves and very large fruit, hardy to Baldwin County, AL in 1972. Performs 5 degrees below zero F. better in Deep South. Holds leaves longer and develops good autumn Cultivars of color; 20 feet tall. Probably not as Kousa Dogwood, hardy as most 'Pluribracteata' forms. Cornus kousa 'Welchii'. Perhaps the oldest selection with tri-color variegation, 'Aget'. Chance seedling. Large bracts, it has leaves that are a combination re-blooming or long-blooming bracts of green, creamy white and pink. may persist from June to September. Best in partial shade to avoid leaf scorch. Spectacular rose red to red 'Akabana' . Originated in China. purple fall color, white bracts. Does Growth habit is consistent with the not perform well in the South and species. Said to have perfect pink bracts, but the warmer the weather, generally should be planted in 'Augustata'. partial shade. Sparse bloomer. the poorer is the expression of red Credit: Willard T. Witte Sometimes reverts to green foliage pigment. There is some question as type and these reversions should be to whether this is distinct from pruned immediately as they occur. other pink-blooming cultivars, as A selection called the 'Kingsville 'Akabana' is the Japanese generic Form' has better color and is a name meaning “red flower” that is better grower. applied in Japan to all pink- flowered forms. 'Welch’s Junior Miss'. Rather attractive, large-flowered form with 'Angustata' (aka 'Augustifolia') deep pink bracts grading to whitish and sometimes ascribed to the in the center and small white bract species Cornus capitala by some tips. Found as a wild plant in 1957 botanists. in Zone 7 or 'Big Apple'. in Mobile County, AL. A rather warmer climates, semi-evergreen Credit: Willard T. Witte

13 NY. Plant is upright, but lateral 'Madame Butterfly'. Extremely branches are weeping. Forms floriferous plant with flowers borne graceful rounded crown, leading on long pedicels and long narrow branches weep 2 feet from highest floral bracts turning vertical about point of curve, 7 feet high and 4 to the midpoint of their length – giving 5 feet wide after 12 years. the appearance of “swarms of butterflies” on the branches. GalileanTM. One of the newest introductions. Has enormous hunter 'Milky Way'. This cultivar derives green leaves and large white bracts. from a group of 15 seedlings of the 'Blue Shadow'. A very broad, upright, vase-shaped chinensis type selected, propagated Credit: Willard T. Witte tree, becoming rounded at maturity. and released by a prominent mail order nursery in Perry, Ohio in the 'Gold Cup'. Leaves slightly 1960s. Trees bloom at an early age. In concave with a gold blotch in the commerce, it may not always be a center of the leaf. vegetatively propagated cultivar, but it may be a seedling from a small 'Gold Star'. Leaves green with group of selected parents. This is a irregular, butter-yellow blotch in very broad, bushy form with distinctly center through spring and summer. flaking mottled bark on older Will revert to green, as is true for branches. It is suitable for small many plants with the center landscapes. 'Milky Way' may be a Heartthrob TM. variegation. All green shoot commercially manufactured name for Credit: Willard T. Witte reversions should be pruned out. this group of plants rather than a Introduced in 1983 by Brookside discrete clone; nevertheless, these Gardens from Japan. Quite plants appear more floriferous. 'Blue Shadow'. Blooms at an early age. Very dark green foliage, with a handsome, but appears quite slow . Flowers said to be 7-8 blue sheen or undertone. Some white growing. Bracts are white. Usually 'Moonbeam' inches in diameter, on long bracts may remain at fruiting time, does not scorch in full sun. peduncles inclined so blooms are excellent fall color and very heat readily visible at eye level. Plant tolerant. One of the best selections 'Greensleeves'. This is a fast hardy to 20 degrees below zero F. for the mid-South. growing tree, with symmetrical branching. The leaves are probably Large leaves. the darkest green of the kousas. The . 'Bush’s Pink'. Pink bracts hold their edge of the leaves is like waves. 'National'. Vigorous, vase-shaped color well through the whole Prolific blooms. tree; dark green foliage. Exfoliating flowering season, at least in cool bark, large creamy white bracts, climates. Heavy bloomer has same HeartthrobTM. A very new fruits are larger than normal. New growth rate and size as species. The introduction ('Schmred') with a deep growth is reddish. leaves show red pigment. red, burgundy bloom, but flower color is not as intense in the mid- 'Porlock'. Said to be a hybrid of C. 'China Girl'. A Holland introduction South as in the Far West. capatata, originating in an English selected for very large bracts. Blooms garden as a self-grown seedling. at an early age. Large fruit. 'Julian'. Bracts curved up at tip, Foliage may be partially evergreen excellent fall color, large fruit in milder climates. A large vigorous 'Chinensis'. Not valid as a cultivar greater than 1 inch across. plant. Bracts creamy-white, but age name and relatively meaningless as a to pink. variety name, but used in the nursery 'Little Beauty'. Shrubby form from trade as a generic adjective signifying wild collected Korean seed, distributed 'Radiant Rose'. Large pink flower, more vigorously growing, free- by State Arboretum. plant with spreading arching habit. flowering plants with broader leaves Red pigment in leaves and branches. than the “Japanese” type. 'Lustgarten Weeping'. Weeping type Grows to 25 feet. Red fall color. May with no tendency for stem or trunk be similar or identical to 'Satomi'. 'Dwarf Pink'. The plant was found to develop upward. Said to be wild in Gumma Prefecture, Japan beautiful because the flowers are 'Rochester'. A selection and produces light pink bracts. Low, positioned along the weeping stems with more vigor and larger, creamy spreading growth habit with a so they are directly in view. A 12- white flowers than most kousas. maximum height of 6 to 9 feet. year old plant is 10 feet wide and 2-3 feet high. Branches arch 12 to 15 SamaritanTM. One of the newest 'Elizabeth Lustgarten'. Selected inches above ground. Branches can introductions and an offspring of from seedlings grown by be grafted on a standard to produce 'National'. Variegated creamy white Lustgarten Nursery, Long Island, a small weeping tree. and green foliage remains attractive

14 all summer. White bracts, vigorous boldest on new growth; older foliage 'Willamette'. 1995 growth, radiant pink and burgundy reverts to green with a light green introduction. Holds dark green fall color. edge, variable expression, small foliage color even in hot, dry flowers and normal growth habit. summers. Excellent fall color, prolific 'Satomi'. Pink-flowering form named Not as colorful as 'Goldstar'. flowering. in Japan and introduced to Europe and U.S. in the 1980s. Red pigment 'Trinity Star'. Selected by an Oregon 'Wilton'. 1978 New Jersey in leaves and branches. Excellent fall nursery. New growth is a mottled show introduction. Plant holds flowers color. Hardy to -20F. This is the of pink, green and white. Leaves are longer than normal. correct name for 'Rosabella' and 'New clustered in a twisted whirling pattern, Red'. Best bract color in light shade which forms a flat-topped dense outline. 'Wolf Eyes'. Center of leaf is gray- and cooler climates. Disease-prone. Fall colors are pink and red. green, with a bright white margin that is scorch-resistant; leaf surface 'Snowboy'. Leaves pale gray-green 'Triple Crown'. Plant with small is somewhat rippled. Slow-growing, with regular to irregular white margin and dainty growth habit, heavy compact habit. White bracts have 2 to 5 mm wide and with occasional flowering with blooms mostly in less impact than on green-foliaged splashes of yellow-green, pink or paler triple clusters. Plant hardy to -20F. cultivars. One of the best and most gray-green variegation throughout. Source from Milton, MA. stable variegated forms. Not a particularly stable form and not particularly vigorous. Slow-growing 'Variegata'. There is more than one 'Xanthocarpa'. Yellow fruits. Several and shrubby. Foliage may scorch in variegated form under this name in forms may pass under this name. full sun. Introduced in late 1970s by cultivation. The cultivar originated Brookside Gardens from Japan. in Japan and was introduced to Long Many other cultivars have been Island, NY in 1862. Leaves can be selected and named with various 'Speciosa'. Very dark green leaves green but heavily streaked with attributes of growth habit, flowering, curl slightly at margins, imparting white, yellow or gray-green; foliage variegation, and fruit size an interesting bicolor effect due to marginal or centrally variegated, and color. Few of these are readily the lighter undersides. Large white sometimes all on the same plant. available, but some may be obtained bracts. Hardy to -15 F. Slow-growing. Variegated kousas are usually slower from specialist nursery growers or growing and often are unstable with found in arboreta. New cultivars 'Square Dance'. Upright growth branches of the variegated leaves continue to be introduced, for habit with flowers most visible from reverting to green, which must be example 'Samaritan', 'Christian above. Hardy to 5 degrees below zero pruned to maintain variegation. Prince' and 'Galilean'. Some are too F. Named for the square pattern of new to be described. There appears the bracts. Good fall color. 'Weaver’s Weeping'. Exceptionally to be increasing interest in using heavy flower display on weeping improved C. kousa cultivars in 'Steeple'. Upright growth habit, branches. Easy to train a dominant American gardens because of their foliage deep green, glossy, with good leader with remaining branches improved drought and heat tolerance. fall color. 1961 source from Martha’s cascading toward the ground. Vineyard, MA.

'Summer Majesty'. Long blooming season with “bracts like snow banks,” which after 3-4 weeks acquire a pink blush for another month. A mature tree would be 20-25 feet.

'Summer Stars'. Heavy-blooming variety retaining flowers six weeks into summer. The fruits supposedly develop with the bracts still present. Robust dark green foliage changes to reddish purple in fall. Drought-tolerant. Introduced by a New Jersey nursery from a Long Island, NY source.

'Sunsplash'. A slow-growing form with bright yellow and green variegation and orange fall color.

'Temple Jewel'. Subtly variegated foliage of green, gold, and light pink, 'Wolf Eyes'. Credit: Willard T. Witte

15 'North Star'. Strong, vigorous creamy white as they age. Cultivars of growth; dark purple, young shoots; Extremely floriferous. Pacific Dogwood, and larger flowers than the species. Cornus nuttallii Leaves have wavy margins. Rare. ConstellationTM. Vigorous and erect when young. More like C. kousa Partly because of its smaller 'Pilgrim' . Southernmost specimen than C. florida in branching habit, range, there has been less activity tested by the Saratoga Horticultural but with more branches near the in cultivar development in this spe- Foundation in . Found ground. Mature height at 20 years cies. Pacific dogwood is difficult to wild along highway Rt. 17 near estimated at 22 feet, with an 18-foot grow in the Eastern U.S., in part Santa Cruz County. Blooms up to 4 spread. White egg-shaped bracts with because the bracts do not completely inches across. acute tip do not overlap. Bloom season starts about three days after cover the flower cluster during the 'Eddie’s White Wonder'. Hybrid of most C. florida stop blooming and winter, leading to cold injury of the Pacific dogwood and flowering lasts about two weeks. Extremely exposed flowers. dogwood from controlled cross made floriferous. Wine red fall color, by a West Coast nursery. Combines holding leaves late into the season. 'Boyd’s Hardy'. Propagated from larger flowers of the former with the sole survivor of a batch of excellent autumn color of the latter. CelestialTM (formerly GalaxyTM). seedlings grown in Tennessee that Branches becoming pendent with age. Begins bloom 4-6 days after Ruth withstood 19 degrees below zero in EllenTM. At first, bracts form a deep 1964. Rare. cup and have a greenish tinge, but they flatten out and become fully 'Colrigo Giant'. Blooms up to 8 Interspecific Hybrid white in a few days. Bracts are inches across with overlapping, cup- Dogwoods rounded, well textured and slightly shaped bracts. Extra large, heavy- Chief among these is the overlap. textured green leaves; wonderful fall Stellar series introduced by color. Cultivar name formed by Rutgers University in the early Ruth EllenTM. Mature plants wider combining the initial letters of the 1990s, which resulted from crosses than tall, estimated at 19 feet in Columbia River Gorge, OR, where it between kousa dogwood and height and 24 foot spread after 20 was found before 1963. flowering dogwood. These years. White bracts become showy as cultivars grow fast when young, flowering dogwood season ends. 'Eddiei' . Leaves are green-streaked and take several years to develop Bracts do not overlap and are round and spotted with gold. Discovered a heavy floral display and to slightly egg-shaped with a growing wild about 1918 by H. M. spreading branching habit. They tapering base and a bristle tip. Eddie. are distinctly upright growing Susceptible to powdery mildew. when young. In flower form and 'Goldspot'. Striking leaves, heavily blooming time they are StardustTM. Appears to have dropped splotched with gold. Similar to intermediate between the parent out of nursery production since 'Eddiei'. species. Except for Ruth EllenTM introduction. Bracts do not overlap. they appear to be generally free TM from the major dogwood diseases Stellar Pink . Vigorous and erect and insects. They are all sterile when young. Mature size and form and set no fruit, and the energy similar to Constellation TM. Flower saved appears to be spent in heads are without a stalk. Rounded, flower bud formation, as all are overlapping soft pink bracts, with exceptionally floriferous. They more intense coloration in cooler have been patented and weather. Bracts are egg-shaped with trademarked. We list the a short acute tip and tapered base. trademark name. Bloom season begins about six days There are also hybrids after C. florida ends. between Pacific dogwood and flowering dogwood (see 'Eddie’s 'Norman Hadden'. Probably a White Wonder' above) and hybrid of C. kousa and C. capitata, between kousa dogwood and C. Himalayan Evergreen dogwood, an capitata, Evergreen Himalayan Oriental warm temperate to dogwood (see 'Norman Hadden' subtropical species with blooms and and 'Porlock' below). fruits similar to C. kousa. A mature tree in southern England in 1989 Stellar PinkTM of the Stellar series. A Aurora TM. Vigorous and was about 12 feet tall and 16 feet hybrid cross of Cornus florida and upright when young. Bracts are wide. Bracts open creamy white in Cornus kousa. white and have a heavily textured, June and age to a deep pink in July. Credit: Willard T. Witte velvety appearance that becomes Virtually unknown in the U.S.

16 'Porlock'. Same type of cross as the case when dogwoods are or to affect soil structure. In 'Norman Hadden'. The plants appear planted in managed land- warmer climates, January can very similar to C. kousa in foliage scapes. Soil is piled around be suitable, weather permitting. characteristics, but hardiness and some trees and taken away Dogwoods grown in field pro- blooming is unknown. from others. In other cases, duction and harvested with a soil is compacted over the root soil ball, called balled and system. The dogwood has a burlapped or B&B, are typically How to Grow the shallow, fibrous root system available from nurseries in late Flowering Dogwood and can be seriously affected fall to early spring. It is best to The flowering dogwood will by fill soil. Digging or ditch- purchase a B&B dogwood within grow in a variety of exposures ing may cut some roots. a few months of harvest. and soils, but it does best in a Trunks are often “de-barked” Container-grown dogwoods well-drained soil that receives by lawnmowers and string are offered year around and can regular rainfall throughout the trimmers. be planted any time of the year, growing season. Dogwoods will • Native dogwoods occur where providing soil moisture is grow in sun or shade, but in they are in harmony with the available. nature, dogwoods are seldom environment. Borers attack Dogwoods are harvested in found growing in full sun. The few natural understory dog- the dormant season as bare-root natural environments for dogwood woods, for instance. plants, but generally they are are in partly shady places and the sold as liners to other growers. edge of woodlands. Flowers are Although nature has win- Seldom are dogwoods harvested more abundant and typically trees ning ways, we can change some of as bare-root plants sold in the are shorter and more compact in them and still grow dogwood landscape market. If you should sun than in shade. Planting successfully in full sun, in the obtain bare-root plants, keep the dogwoods in full sun without lawn and in the woods. Too many roots moist and do not allow irrigation is a major contributor of our transplanted dogwoods now them to dry out. Plant the trees to stress that may cause plants to die within the first few years. By as soon as possible. Dogwoods are die after transplanting, or may be learning more about dogwood, temperamental as bare-root more likely to be invaded by most of this loss can be prevented. plants and survivability will dogwood borers. increase if planting is done Thus, site selection is very quickly after being lifted from important. In choosing a site to Soil the nursery. We do not recommend plant flowering dogwood, it may The kind of soil is not of transplanting trees from natural be wise to observe dogwoods in great importance in growing areas because of the danger of their natural environment. Some flowering dogwood. The best soil spreading disease, namely natural dogwoods die of drought, would be slightly acid with a fair Discula anthracnose. Purchase disease and pest attack along the amount of organic matter and your dogwoods from a reputable way, but much can be learned would not dry out quickly in garden center. Avoid trees with from observing natural sites. summer, like a gravelly soil. The Consider the following: broken or dead branches, trunk most important factor is for the damage or leaf spots. These are soil to have good internal drainage • In natural environments, few signs of unhealthy plants. so it is not saturated with water dogwoods are found in full during wet weather. Dogwood sun or out by themselves. absolutely will not tolerate satu- They are found at the edge of rated or poorly-drained soil, even How to Plant woodlands or mixed with for a few days. Dogwood naturally occurs other kinds of trees, usually as an understory tree in areas larger than the dogwood. with high organic soil and • All of nature’s trees start from plenty of natural mulch. They do seed and grow in place, so When to Plant not perform well in areas of poor there are no transplanting The best time to plant drainage, or extremely dry sites. problems. dogwood is during the dormant Even though dogwoods naturally • In nature, there are few season, late fall through spring, occur in partial shady areas, chances for injury to the tree’s when the ground is not frozen they can perform well in full trunk and roots. This is not or so wet as to hamper digging sun, provided adequate soil

17 likely to create a “pot” where roots grow in the amended soil, but do not penetrate and grow well into the native soil. The only time we would recommend amending the backfill is in a gravelly soil where moisture retention is needed. For balled and burlapped Figure 2a. Measuring the planting depth of a B&B root-ball. trees, the burlap may be left on, provided it is natural burlap. Plastic burlap should be re- moved. An easy way to deter- mine what type of burlap you have is to try to burn a small piece. Plastic burlap will melt before burning. Be sure to completely remove any strings from around the stem or trunk and fold the burlap away from the trunk. The string may be sisal or polypropylene plastic and eventually will girdle the trunk if left on. Large B&B trees are often dug with a mechanical spade and placed in wire baskets lined with burlap at the nursery. The wire basket helps support the Figure 2b. Planting a B&B tree. root system while moving the Credit: UT Extension PB 1621, Planting Ornamental Plants by Donna C. Fare, 1999 tree. Always handle a large tree by the root ball, not the trunk. Large trees may require two or moisture is available. Dogwoods thoroughly, the plant will more people to carry them, or have a shallow root system that slowly settle and subsequently the use of a tree dolly. Do not can be adversely affected in be too deep. Laying a shovel remove the burlap and twine periods of drought. Good plant- handle or straight edge across before the plant is set in the ing sites and proper planting the hole helps to determine the planting hole. The tree should procedures will ensure the proper depth (Figure 2). Al- be placed on solid ground rather dogwood gets off to a good ways avoid setting the dogwood than loose soil. Untie any rope, healthy start in the landscape. tree any deeper than it grew jute or polypropylene twine that The first rule for planting before transplanting. It is is tied around the trunk. Pin- any tree is to dig a hole large preferable to set the tree a ning nails should also be re- enough to accommodate all the couple of inches higher than moved from the upper part of roots. A good practice is to dig the soil level, especially if the the root ball. It is not necessary the hole two to three times soil is a heavy clay. to remove the wire basket, but wider than the ball of soil or Use the same soil that cut off the top ring and fold the spread of the roots. Dig the came out of the hole for back- burlap down or cut off the top hole with sloped sides, rather fill. The assumption that soil third of burlap. Backfill the than straight, to give the new amendments like peat moss hole halfway with existing soil, feeder roots maximum room to will be helpful to the plant’s tamp down lightly, water to grow. Don't dig any deeper establishment and survival has firm the soil and eliminate air than the root ball or container. not been proven in research. pockets. Finish backfilling and Unless backfill soil is firmed Adding soil amendments is water again. Rake the soil

18 evenly over the entire area so than soil; thus staking may be such as 10-10-10 or 13-13-13 and the backfill is even with the essential. However, do not stake spread it over the ground under existing soil line. The top of the the plants so tightly that they the canopy and branches. Use up ball or container surface should can not move at all. A certain to 8 ounces (1 cup) per inch of be visible. Remove excess soil. amount of movement or flexing trunk diameter. Water in well to Cover the entire area with 2-3 tends to strengthen the trunk as prevent damage to grass. For inches of mulch. A thorough new growth occurs. Remove the optimal growth, apply fertilizer soaking with water finishes the stakes and guy wires at the end just as buds start to swell in the planting operation and is a good of the first growing season. spring, before leaves start to grow soil-firming technique. Lawnmowers and string (February and March) and an Water container plants trimmers injure many young application in May-June. If this 1 prior to planting. Remove the dogwood trees, and those injuries technique is used, apply /2 cup (4 plastic container. Check the attract dogwood borers. The best ounces) at each application. outside of the root ball and cut way to keep the lawnmower or Too much nitrogen along any circling or girdling roots. If string trimmer from injuring the with too much water may the root system is matted on the trunk is to maintain a weed-free encourage strong vegetative outside of the ball, use a sharp and grass-free mulched area growth. This may not be at all knife to make three or four extending out 18-36 inches from bad, especially when the tree is shallow vertical cuts from top to the trunk. young. However, excessive bottom. This is a form of root Flowering dogwoods are vegetative growth may be pruning and will help stimulate especially prone to borer attack responsible for a poor set of new root growth. Do not be during the first two years after flower buds. In such a case, afraid to cut twisted roots. planting. Tree stress and trunk using less nitrogen will probably A primary rule for plant- injury invite borers. A spray yield more flowers. It may ing a dogwood tree is never let schedule, as discussed in the require one to three years for a the roots become dry. For trees Insects section of this publica- fast-growing tree to “slow down” with a ball of soil, this is tion, should be followed begin- enough to set a good crop of usually not a problem. Still, ning early in the first growing flower buds. balls or containers that are season to control this pest. The stored for a while must not be spray schedule combined with allowed to dry out. For bare- keeping the trunk free from Mulching root seedlings, keep roots injury will minimize the risk of The forest floor is mulched covered with a damp cloth, borer damage. naturally with leaves. The burlap or moist packing mate- nutrients are recycled. In land- rial such as moss, mulch or scapes, newly planted and older wood shavings. The fine roots Fertilizing trees will benefit from mulching. should never be allowed to dry Little or no fertilizer is Mulch helps to hold soil moisture out. Healthy dogwood roots will recommended the first season. and can reduce or eliminate have white growing tips. Research has shown that the tree competition from weeds and will not respond much at all to grass. If weeds start to grow in fertilizer the first growing season the mulched area close to the Care After after transplanting. When there trunk, hand-weed that area. Do Transplanting is a desire to obtain faster not use a lawnmower or string After transplanting, trees growth, fertilizer can be applied trimmer close to the tree trunk. more than 8 feet high may need beginning early in the second Mulch can be organic to be secured with stakes or guy season. The tree may never need material, such as composted wires during the first year to extra fertilizer if the soil is leaves, grass clippings, pine prevent them from being blown moderately fertile and growth needles, wood chips or shredded about or dislodged by high winds. and foliage color are acceptable. bark. Avoid using any organic This may not be necessary with A well-fertilized lawn will benefit material that is fresh or not large B&B plants due to the trees planted in the lawn. composted. A layer 2-3 inches weight of the root ball. Large- The best fertilization deep, extending out about 2-3 container dogwoods are grown in practice for dogwood trees is to feet from the trunk, is recom- a media that is much lighter use a complete garden fertilizer mended. Don't overdo it. Mulch

19 more than 4 inches deep or piled the same as those of a tree suffer- Will My up against the trunk can be ing from a lack of water. detrimental. Excessive mulch can Caution. Transporting plants Dogwood Bloom? impede water and air movement in leaf can cause severe injury. The question, “Will my to the root system, and if mulch Avoid windburn or desiccation by dogwood bloom?” is asked many keeps the trunk bark continually covering the plants with a tarp or times upon purchasing a tree. moist, it could cause decay. cover during transport. Do not let Homeowners can be assured the Additional mulch should be covered plants sit in full sun. answer to that question is nearly added every couple of years to Damaging temperatures build up always “Yes.” Probably all replace that which slowly decays. quickly. Lift plants by the root healthy dogwoods will bloom. ball, not the trunk, to prevent root Most unhealthy ones will, too. In breakage in the soil ball. The fact, a tree fatally injured by planting techniques described borers or lawnmower damage Watering will bloom heavier than normal, For most soils and most above should start your dogwoods off to a long and healthy life. although perhaps with smaller years, natural rainfall is usually flowers. Such an injured tree will adequate to support good growth often die during the summer of dogwood. But during the first following the extra heavy bloom. two growing seasons following Pruning Not all dogwoods begin planting, dogwoods often require Once a dogwood is planted blooming at the same age. extra water to eliminate stress and established, it needs little or Nursery-grown plants of some and promote new growth. How- no pruning. Remove dead, dis- cultivars have flowers the second ever, be sure to water trees, even eased or broken branches as soon or third year, while native trees mature trees, during severe as they become apparent. Re- may be 4-6 years old or older drought periods at the first sign move any suckers that appear at before blooming. One can tell by of leaves wilting. Dogwoods are the base of the trunk, especially September if a tree will bloom shallow-rooted and cannot draw on grafted trees. Otherwise, the next spring. The button- on moisture reserves deep in the pruning is a matter of personal shaped flower buds are formed soil. Drought-stressed dogwood preference. Some people prefer the summer before blooming. If trees are apt to wilt or drop some limbs to branch out low to they are not present on the tree leaves and lose part or their the ground. Others may prefer to by September, the tree will not entire crop if they do not remove low limbs or trim back flower in spring. If the large receive supplemental watering. limbs near a walkway or against buds that tip the branches can be The most severe drought stress a house. Multiple trunks may be found, the tree should bloom. usually occurs in late summer. either eliminated or retained. In There is very little danger of cold Avoid overwatering newly any case, make pruning cuts weather killing the flower buds planted dogwoods. Seldom is it clean and nearly flush with the except on the extreme northern necessary or desirable to water remaining branch. Leave only a edge of the dogwood range. young trees more often than once “shoulder.” Never leave a branch Dogwoods do not always a week. One good soaking weekly stub. Pay attention to borer bloom the same amount each (about 1 inch of water) or even prevention practices, because year. In fact, if a healthy dog- every other week would be far pruning wounds are attractive wood tree blooms heavily one better than a small amount of to borers and serve as entrance year, followed by a large berry water daily. Water applied in sites. Late winter to early crop, then the tree will likely small amounts seldom provides spring is the best time for bloom poorly the following year. adequate moisture throughout the pruning. Pruning may be done The simple reason is a large root system and encourages root any time it is needed, but most amount of energy is required to growth near the soil surface. Roots practitioners prefer the dormant produce a large number of need air to live just as much as season. Rapid spring growth flowers and fruit. Too little they need water. Overwatering will begin the healing process energy then will be available for drives the air out of the soil and faster than at any other time. the tree to produce a large num- will likely result in root decay. Even pruning during bloom is ber of blooms the following year. The symptoms (wilting and leaf not damaging to the tree and This is why a “good dogwood scorch) of a tree dying from root can sometimes yield some nice show” one year is often followed rot caused by too much water are branches for decoration indoors. by a “poor show” the next. Very

20 likely the year following a “poor and use are constantly changing. female lives only seven to show” will be good again. Consult with your local Extension nine days; during this time she Certain individual dogwood agency for the currently recom- lays the eggs that produce the trees have the habit of coming mended chemical controls. destructive larvae. New into partial bloom in the fall, at continue to emerge, mate and lay least in some years. One cultivar, eggs over an extended period of 'September Dog', was even Insects time from infested trees. A larva selected and named because it hatched during one year will not consistently showed this odd The Dogwood Borer make an adult until the following behavior. Such trees are usually year. The larva does its damage The dogwood borer, from a southern selection and the while tunneling and developing scitula (Harris), is flower buds may have a different inside the tree from one year to the most destructive insect pest dormancy pattern than others. the next. After this feeding of the dogwood. Damage is done Some flowers may develop when period, the larva forms the pupa, under the bark on the trunk and summer and fall stress periods and in eight to 12 days the adult at the base of older branches by are followed first by moderately emerges from the pupa case. a cream-colored larva with a cool nights and then an unsea- reddish-brown head. The larva sonably warm period in the early Damage – Eggs laid on the has two reddish-brown spots fall. These flowers are almost dogwood trunk by the moth hatch directly behind the head on the always on abnormally long into very small larvae in eight to thorax. The full-grown larva is flower stalks with smaller than 10 days. Some of the young about 0.6 inch long. The adult normal bracts that are often dogwood borer is a blue-black contorted and may be blushed moth with clear wings and some with pink. If berries do form, yellow markings. The adult moth they are lost to frost, so fall does not damage the tree. blooming is no advantage to the These moths emerge over a plant. Fall dogwood blossoms are four-month period from spring an interesting abnormality that through September, beginning in does not appear to hurt the tree. March in the extreme South, in late April in eastern Tennessee, in mid-May in Virginia and late Integrated in May in . The Management of Dogwood borer adult moth. Insects and Diseases Credit: Frank A. Hale of Flowering Dogwood

Dogwoods can be killed or seriously damaged by insect and disease pests. Poor cultural practices can often cause a decline in the physical condition of the tree favorable for infestation by insects and diseases. Periods of hot, dry weather, trees growing in full-sun location and accidental injuries with garden tools fre- quently provide the opening through which these pests enter the plant tissues. Specific pesticide information is not given in this publication. Pesticide registrations, labeling Dogwood borer larvae damage. Credit: Mark T. Wilson

21 larvae find an opening in the trunk from the larva and by bark in which they can enter. removing the larva after it is in Once inside, they are well pro- the trunk. Obviously the first tected and begin feeding, but method is best. Prevention may probably will not kill the dogwood take place in one or more of the unless the tree is very small. following ways: Usually it takes several larvae in one tree to completely kill the • Make pruning cuts in late tree. The tree will die whenever winter to facilitate rapid one or more larvae eat completely healing during rapid spring Asian ambrosia beetle in ambrosial fungi around the trunk and block the diameter growth. filled brood gallery. Credit: Frank A. Hale flow of food from the treetop to • Avoid physical injury to the the roots. Often the tree will die tree by unnecessary back to the point of injury, and or bruising. Mulch around new shoots will arise below this trees or remove grass by point. These new shoots can often hand rather than mowing be kept to regrow a new tree close to a tree. providing additional borer injury • Insecticides can be used on does not take place. the lower branches and trunk Fortunately, the dogwood to kill newly hatched larvae borer will not attack all dog- before they can enter the tree. wood trees. The adult moth is a Once inside the bark, the “light-loving” insect. Native larvae may not be killed by trees in their natural understory insecticides. For maximum habitat are seldom attacked. protection, an insecticide Trees that are never damaged residue should be on the by sunscald, lawn mowers, trunk during the entire egg- construction equipment or strong laying period. Spray the winds are much less likely to be trunk, the lower limb scaffold attacked by borers than trees and the soil around the bark Asian ambrosia beetle frass from the trunk of a crape myrtle. that are first stressed and of the trunk. These preventa- Credit: William G. Hudson injured in some way. tive insecticide sprays will also aid in the control of Control – Damage from flatheaded borers. the dogwood borer can be pre- be caused by gallery formation or vented by protecting the tree Asian Ambrosia Beetle the ambrosial fungi. The Asian The Asian ambrosia beetle, ambrosia beetle is thought to be a Xylosandrus crassiusculus vector of wilt fungi. (Motchulsky), is able to attack Signs of attack include apparently healthy trees, shrubs toothpick-diameter tubes of Precautionary and vines of a wide host range. sawdust-like frass (excrement) Statement The reddish-brown female sticking out from the many small To protect people and the are 2.1 - 2.9 mm long, holes in the trunk or infested environment, pesticides should be while the males are only 1.5 limbs, wilting and oozing sap. The used safely. This is everyone’s mm long. The larvae are white, flight of the adult female beetles, responsibility, especially the user. legless, “C-shaped” and not determined by trap catches, Read and follow label directions easily distinguishable from the occurs in late winter to early carefully before you buy, mix, apply, spring during warm spells while store or dispose of a pesticide. larvae of other ambrosia beetles, According to laws regulating bark beetles and most weevils. the trees are still dormant. If pesticides, they must be used only The larvae feed on the ambrosial trees are being attacked, recom- as directed by the label. Persons who fungi that the adults introduce mended insecticide sprays should do not obey the law will be subject into the galleries. The wilting and be initiated at 10-14 day intervals to penalties. death that occur in many of the and discontinued only after the attacked plants is not thought to plants have leafed out.

22 Dogwood Club Gall North Georgia, from May The dogwood club gall is through July in recognized as a distinct swelling and from late May to early near the tip of branches. It may August in . They feed be found on transplanted trees on the midvein on the underside and those growing in the natu- of the leaf that can cause the leaf ral state. The gall is caused by a to curl downward. This leaf small (2 mm long), reddish- feeding causes little damage. The brown fly, Resseliella clavula more serious damage is associ- (Beutenmueller). ated with egg laying and the resulting larva. The female adult Dogwood club gall at tip of twig. Credit: In the spring the female fly Frank A. Hale lays eggs in the small terminal beetle uses its mouthparts to leaves. The resulting tiny larvae make small punctures around the bore into the twig at the base of a branch to girdle it. Two girdles 1 leaf. One month after eggs are are made /2 to 1 inch apart laid, swelling is noticeable. The about 3-6 inches from the tip of a larva completes its growth inside small branch. The beetle then the gall by September, exits and lays an egg between the two drops to the ground to overwinter. separate girdles. The egg hatches The adult flies will emerge the in seven to 10 days and the next spring to repeat the cycle. young larva tunnels into the bark. The developing larva tunnels down the center of the Damage – A light infesta- Wood fibers pushed out of hole in the twig tion of club galls will hardly be limb, expelling frass through a by dogwood twig borer. Credit: Frank A. noticed and will not stunt tree row of small holes in the bark. A Hale growth. Most buds that develop portion of the branch may be cut beyond the gall will die. Trees off from within. The larva passes with many galls will not be the winter in the center of the attractive and the number of stem. The borer pupates between flowers the following spring will two plugs of sawdust. The devel- be reduced. opment from egg to adult usually takes two years. Control – The club gall can be controlled by pruning and Damage – The wilting of insecticides. By pruning out twigs leaves and the drooping girdled containing galls before August 1 twigs are the main evidence of damage. Since the beetle occurs Dogwood twig borer larva in hollowed out and burning them, future infesta- dogwood twig. Note plug of coarse woody tions can be reduced. in small numbers, trees are not fibers at end of twig. Credit: Frank A. Hale likely to be killed, but appear- Dogwood Twig Borer ance may be impaired. The dogwood twig borer, dogwood in the Great Lakes (Swerderus), Control – Prune infested states and the Northeast. Saw- causes wilted leaves or the limbs in the spring before the flies are classified in the same dropping of girdled branches. adult beetles emerge from infested insect Order, Hymenoptera, as Damage is done by a dark twigs. Make pruning cuts below ants, bees, wasps, yellowjackets, green, long-horned beetle that the tunneled part of the branch hornets and horntails. While measures about one-half inch and burn prunings. This pruning they do not sting, the adult long and has three black spots cut will often be 6 inches or so female sawflies use their serrated on the light tan prothorax below the girdled area. ovipositor to insert eggs into the (directly behind the head). The leaf tissue. The adults emerge beetle is usually found only in Dogwood Sawfly from late May through July (one small numbers. The dogwood sawfly, generation per year) and soon Adult beetles begin to Macremphytus tarsatus (Say), is a deposit more than 100 eggs in appear in April and May in defoliating pest primarily of gray the underside of a single leaf.

23 The larvae of foliar feeding Control – Spray the foliage Control – Lady beetles and sawflies have more than five pair with recommended labeled other predators and parasitoids of fleshy prolegs on the abdomen, insecticides when leafhoppers will often control this pest while butterfly, moth and skipper appear. Repeat applications at 7- without the need for insecticide if caterpillars () have a 10 day intervals as needed. given time. Dormant oil can be maximum of five pair. applied in late winter while the Cottony Maple Scale trees are still dormant. Target Damage – After hatching, The cottony maple scale, the crawlers (first active imma- the yellowish orange larvae Pulvinaria innumerablilis ture stage) with a recommended skeletonize the leaf. They soon (Rathvon), is a very large and labeled insecticide in the spring. molt to the second instar stage conspicuous scale insect found on a A couple of applications at and become covered with a wide variety of ornamental plants. weekly intervals may be needed. white, powdery material that Adult females are generally can be rubbed off. They then reddish-brown and have a median Walnut Scale devour all of the leaf except for ridge. Adult females overwinter The walnut scale, the midvein. The last instar and enlarge rapidly in the early Quadraspidiotus juglansregiae larvae are 1 inch long with four spring. The white ovisacs contain- (Comstock), can also cause rows of black spots in addition ing up to 1,000 eggs are developed extensive damage to dogwood by to the white material. The under the raised abdomen in mid inhibiting the terminal growth larvae leave the plant in search to late spring. The crawlers move of limbs and by encrusting the of a place to overwinter, where to the leaves in late spring, where limbs and trunk leading to they bore into rotting wood and they develop into adults in late death of the tree. Initial infesta- can even damage wooden clap- summer. This scale produces large tions occur on the underside of board, wood-fiber wallboard or quantities of honeydew, which the limbs, but will completely garden furniture. frequently supports the growth of encrust the limbs within two to sooty mold. three years. The walnut scale Control – Spray the foliage with recommended labeled insecticide when dogwood saw- flies are first detected.

Rose Leafhopper Dogwood leaves become white and stippled due to the feeding activity of the rose leafhopper, Edwardsiana rosae (Linnaeus). Leafhoppers over- winter as eggs in the stems of , blackberry or raspberry. Eggs usually hatch in the spring after the threat of frost has passed. The young, greenish- white, red-eyed nymphs feed on the underside of the leaves until they mature. The first brood of adults migrates to dogwood, maple, elm, apple and other woody plants. They insert eggs into the plant tissue on the underside of the leaves. The eggs soon hatch and the summer generation continues to develop. Several generations will develop during the season. Walnut scale on a dogwood limb. Credit: Frank A. Hale

24 has two generations per year. spin webbing. High populations The adult female walnut scale of two-spotted spider mites, lays eggs in June and again in especially during extended dry August in Ohio, in mid-May and periods, can entirely cover leaves again in mid-August in Califor- with webbing. nia. The crawlers emerge from the eggs several weeks after Monitoring – Inspect they are laid. dogwoods periodically during the spring and summer. Use a Control – Adults are magnifying glass to look for the difficult to control because of mites, cast skins, eggs and their the wax-like protective covering webbing on the underside of over their bodies. Crawlers are leaves. Hold a white card under the easiest stage of the walnut the plant foliage and shake or scale to control. Consult with tap the foliage to dislodge mites your local county Extension onto the card. The mites can be agent for when to expect crawl- observed as they crawl across the ers and apply the recommended card. Observe the top of leaves chemical controls. for the tiny, chlorotic feeding spots on either side of the mid- Two-spotted Spider Mites vein of the leaf. Two-spotted spider mites, Tetranychus urticae Koch, are Control – It is best to warm-season mites that can begin chemical treatments at the quickly build to tremendous first signs of mites or mite numbers in hot, dry weather. damage. At least two sprays, five They can develop from egg to days apart, will be needed. adult in only eight days at 77-95 Summer horticultural oil sprays degrees F. They attack more than should not be made more than 180 host plants, including 100 once per week. Some miticides cultivated species. Two-spotted have a long residual so that one spider mite populations often application is sometimes suffi- increase on common plants such cient for control of small popula- as violet, chickweed, pokeweed, tions. To slow the buildup of wild mustard and blackberry. resistance to some of the newer They can then disperse to other miticides, the label may limit its plants, including dogwood. use to once per year, or not allow it to be used in successive appli- Two-spotted spider mite webbed in a mass Damage – Two-spotted cations. Some miticides only on the tip of a leaf. spider mites damage leaves by control immature mite stages, so Credit: Frank A. Hale piercing the outer leaf surface a different miticide to control with their sharp, slender mouth- adult mites may be required. may be planted in well-drained parts. When they extract the sap, soils that are high in organic a tiny bit of leaf tissue collapses matter. Weed control practices can in the area of the puncture. cause either mechanical injuries Soon, a minute chlorotic (yellow) In the landscape, dogwoods from cultivation or chemical spot forms at each feeding site. are planted into all types of (herbicide) injury. All of these After a heavy attack, an entire situations. While the inner foliage factors may contribute to the plant may become yellowed, of the trees may be shaded, trees stress of the tree and affect the bronzed, partially defoliated or may be planted in direct sunlight tree’s ability to resist plant pests completely killed. Two-spotted or into full or partial shade. Trees and pathogens. spider mites are generally found may be located in open (airy) To aid in identification of on the underside of the leaves areas or in landscapes that dogwood health problems, a where they feed, lay eggs and contain dense foliage. Dogwoods simple key of common symptoms

25 a.

Symptoms of spot anthracnose include reddish-brown, elliptical spots on (a) bracts and (b) leaves. Infected bracts may be smaller, distorted or destroyed. Credit: Mark T. Windham (both photos)

b.

and signs of dogwood diseases is freeze damage from sudden cold included (see sidebar). Common spells. Later-blooming cultivars, diseases and an overall pest such as 'Plena', were rated as management strategy are de- very resistant to this disease in scribed below. the same trials. Labeled fungicide sprays can Spot Anthracnose be used to control this disease in a. Spot anthracnose is caused specimen plants. Sprays should be by the Elsinoe corni. The applied prior to bud break, after disease is most pronounced on bract fall, a month later and in the bracts of the tree, which September after the new flower makes the disease more impor- buds have formed. tant in a landscape situation. Usually the lower branches are Dogwood Anthracnose first affected by the disease, Dogwood anthracnose is a

which may move rapidly disease that can cause mild b. through the tree canopy. Bracts symptoms like spot anthracnose may have circular to elliptical or symptoms so severe that the spots with reddish borders. On tree dies. It is caused by the green leaves, reddish spots are fungal pathogen, Discula small, circular lesions with dead destructiva. Symptoms of this centers. Spot anthracnose is disease include lesions with usually worse when the weather purple or reddish borders, leaf remains cool and wet. Late frost and twig blights, a profusion of damage may predispose bracts to epicormic branching and/or attack by the pathogen. limb and trunk cankers. The disease usually begins as a Control – Several cultivars lower branch dieback and are susceptible to spot anthra- infected trees may have little cnose and include the cultivars ornamental value. 'Cloud 9' or 'Barton'. These The infection is aided by c. cultivars bloom relatively early cool, wet weather. Dogwood Dogwood anthracnose causes (a) leaf in the spring. In a cultivar trial, anthracnose epidemics are spots, (b) twig cankers and (c) trunk cankers. Credit: Mark T. Windham (all 3 these cultivars experienced worse in trees growing in photos)

26 shaded environments. Trees at Dogwood Canker Phytophthora Root Rot high elevations, planted in The cause of dogwood This disease is attributed to high-humidity areas (such as canker is still unknown after P. cactorum and P. cinnamomi. near streams) and on north- many years of research involving Trees may be stunted or wilt and facing slopes may be more several different organizations. die suddenly. Roots and possibly likely to suffer severely from The disease is characterized by the lower stem may be black and this disease. Research at The cankers on the main trunk that necrotic. The disease is usually University of Tennessee has have rough, cracked bark. Can- severe in low areas where drain- demonstrated that trees suffer- kers are often sunken in the age is poor. ing from water stress are also inner node regions and swollen more likely to suffer severely at nodes. Control – Avoid planting from this disease. trees in areas with poor drainage. Control – Unfortunately, Control – In landscapes, there are no chemical controls. Powdery Mildew cultural practices such as Select plants with smooth, slick The fungal disease placement of trees in sunny, bark and no signs of canker. Microsphaera corni causes powdery open environments to encour- Avoid the cultivar 'Purple mildew. The disease is character- age good air movement; high Glory' because it was highly ized by white aerial hyphae on the foliage temperatures (resulting susceptible to this disease in a leaf surface. Trees with severe from radiant heating); and cultivar trial. Trees with dog- infections may be stunted and the lower relative humidities are wood canker are often infested foliage distorted. Trees with severe sufficient to reduce damage with dogwood borers. from this disease to acceptable powdery mildew infections in 1994 levels. Trees should be pur- chased at reputable nurseries and not dug from wooded areas, where an infected plant could be selected. The Tennessee Agricul- tural Experiment Station has released a new cultivar, 'Appa- lachian Spring', which is resistant to dogwood anthra- cnose. This cultivar should be in the retail market in 2005. Many strains of C. kousa are resistant to this disease. How- ever, not all strains of C. kousa are resistant and caution should be taken when making blanket claims of resistance. Trees in the Constellation series of C. florida x C. kousa hybrids developed by Dr. Orton at Rutgers University may be susceptible under some environmental conditions. Levels of resistance to dogwood anthracnose vary among other Cornus species. Resistance is found in native species such as C. alternifolia and C. sericea and exotic species such as C. controversa and C. mas. Dogwood cankers are characterized by rough and sunken cankers and swollen nodes. Credit: Mark T. Windham

27 were slow to leaf out in 1995. by B. cinerea, are necrotic. Since powdery mildew infection Infected bracts may fall and stick interferes with normal photosyn- to dogwood leaves and cause thesis and cell metabolism, se- lesions similar to dogwood verely infected trees may have had anthracnose. The disease is a reduction in winter hardiness observed during wet, cool because of decreased levels of weather. Control measures are stored carbohydrates when they not necessary for either disease. went dormant. The disease is Powdery mildew infected leaves have favored by periods of warm, dry , caused white powdery fungal growth on their Clitocybe root rot surfaces. Credit: Mark T. Windham weather with cool nights (periods by C. tabescens, usually attacks of high relative humidity). older trees that have been weakened by stress. Leaves may Control – Spraying with be scorched and twigs may die. fungicides labeled for powdery Yellow-brown mushrooms may be mildew should be effective in present at the base of the tree. controlling this disease if applied After the tree dies, black strands early in the epidemic. Trees of fungal material may be found protected with fungicides have under the bark or in soil near significantly increased height roots. To prevent this disease, a. and trunk caliper as compared to maintain healthy, vigorous untreated trees. Once the plants plants. Water plants during have “turned white,” fungicidal droughts. Do not plant trees in sprays have little value. soil with history of this disease. In tests conducted at Au- burn University and at The Virus infections are not University of Tennessee, the red- very common in dogwoods. flowering cultivar 'Cherokee Symptoms include mild mottles Brave' displayed good resistance and mosaics. Virus-infected to this disease. The Tennessee trees may be stunted and more b. Agricultural Experiment Station susceptible to other diseases. has recently released three new Most dogwood viruses are in white-bracted cultivars, 'Karen’s the Nepo virus group and Appalachian Blush', 'Kay’s include , Appalachian Mist' and 'Jean’s cherry ringspot virus and Appalachian Snow' that are tobacco ringspot virus. No resistant to powdery mildew. control is necessary. Variegated cultivars, such as 'Cherokee Sunset', 'Cherokee Leaf Scorch is not a c. Daybreak', 'First Lady' and disease, but a physiological 'Rainbow' are unusually suscep- problem that appears as brown- tible to this disease. ing of leaf tissue between veins and along the margins and tips of leaves. These areas are the Other Dogwood first to brown, as they are the last areas to receive water from Diseases: the roots. Scorch is common Several other diseases may when there is hot, dry, windy d. occasionally damage dogwood. weather during periods of Symptoms of Septoria leaf spot intense sunlight. During these Dogwood cultivars (a) 'Cherokee Brave', (b) caused by S. cornicola and S. 'Karen’s Appalachian Blush', (c) 'Kay’s conditions, the dogwood’s foliage Appalachian Mist' and (d) 'Jean’s Appalachian florida, are small, angular leaf transpires water faster than the Snow' are resistant to powdery mildew. lesions. The disease occurs tree’s roots can replace it. Leaf Credit: Mark T. Windham (all 3 photos) during wet summer months. scorch is common on newly Lesions of Botrytis blight, caused transplanted trees and on

28 species and hybrids that lengthen the “dogwood season of bloom.”

Growing and maintaining dogwoods requires consideration of the following:

a) Select a healthy tree for planting. b) Purchase dogwoods from a reputable nursery; do not dig trees in the wild. c) Select a good planting site. d) Prepare the planting hole. e) Protect roots from drying. f) Water well at planting and during drought. g) Mulch with 2-3 inches of organic material. h)Stake or brace larger trees. i) Avoid mechanical and chemical injury to trees. j) Use insecticides and fungicides Leaf scorch is common during periods of drought. Credit: Mark T. Windham as appropriate. established trees severely Summary Typically after establish- stressed by drought, mechanical The beauty and utility of ment, dogwood trees experience injury, borer injury and after the flowering dogwood, Cornus few problems if maintained soil compaction during construc- florida, explains why it is one of according to these guidelines. tion. Watering trees during America’s most popular native Take proper action against periods of drought can usually ornamental trees. It enhances the insects and disease when they prevent leaf scorch. Mulching beauty of both woods and homes occur. Given reasonable care, the around the base of trees with every spring in its native range. flowering dogwood and its rela- organic mulch such as pine or Cornus florida is the only tree tives can be grown successfully hardwood bark can slow soil recognized by many as “dog- in much of the country and will water loss. wood,” despite the fact that there add beauty to the landscape for are beautiful dogwoods of other many years.

General Disease Management for Dogwoods Growing in Landscapes 1. Select healthy plants. Inspect tree trunks for symptoms of dogwood canker and mechanical injuries and signs of borer infestations. 2. Place dogwoods in full sun if dogwood anthracnose is present. In areas where this disease is not present, place trees in as much shade as possible to avoid dogwood borers. 3. Water thoroughly during drought periods. Avoid wetting the foliage with irrigation systems, especially during evening hours. 4. Maintain dogwoods in a vigorous condition. Avoid mower or weed trimmer injuries by mulching trees. 5. Prune trees to promote good air movement. 6. Spray the dogwood trunks with an insecticide in early April and early July if trees are growing in an area where borer infestations are likely. 7. Select cultivars not known to have unusual problems with diseases and insects. Also select those which are well adapted to cultivation in the landscape. 8. Inspect trees often and send symptoms and/or signs of problems to your county Extension agent for early diagnosis.

29 Key to Diseases of the Flowering Dogwood

1 a) Disease affects the roots...... 2

b) Disease affects the trunk or large limbs...... 3

c) Disease affects bracts, leaves, or twigs...... 4

2 a) Wilted trees with rotted roots...... See Phytophthora root rot

b) Thick strands of fungal growth underneath bark Clitocybe root rot or in adjacent soil...... (see other diseases)

3. a) Bark cracked and fissured; affected area swollen at nodes, sunken at internodes...... See Dogwood canker

b) Profusion of water sprouts; eliptical cankers under bark at base of shoots...... See Dogwood anthracnose

c) Clusters of yellow-brown mushrooms at base of older trees...... Clitocybe root rot (see other diseases)

4. a) Problem occurs on bracts...... 5

b) Problem occurs on leaves...... 6

c) Problem occurs on twigs...... 7

5. a) Small reddish circular/elliptical lesions on bracts; bracts may be distorted and dingy yellow...... ….... See Spot anthracnose

b) Lesions enlarge over time and may have reddish borders...... See Dogwood anthracnose

c) Lesions similar to those caused by dogwood anthracnose; during cool, wet weather, gray "fuzzy" fungal growth present...... Botrytis blight (see other diseases)

d) Necrotic area limited to edges of bracts, bracts may be distorted...... Frost damage (not a disease)

6. a) Twigs blighted, dead leaves hanging from twigs... See Dogwood anthracnose

b) White powdery fungal growth on twigs...... …..... See Powdery mildew

7. a) Small circular lesions with red borders, lesions do not enlarge but may coalesce...... See Spot anthracnose

b) Lesions may enlarge to size of dimes, may be oval, elongated or "run up veins;" lesions with red/purple borders; necrotic lesions on shaded See Dogwood anthracnose foliage may light entire leaf......

c) Lesions small and angular...... Septoria leaf spot (see other diseases)

d) Lesions necrotic, occur where leaves touch or where fallen bracts adhere to leaves...... Botrytis blight (see other diseases) e) White, powdery growth on leaf surface, leaves may See Powdery mildew be distorted......

f) Mild mosaic or mottling in leaves...... Virus diseases (see other diseases)

g) Distorted, twisted, and/or crinkled leaves, severe Herbicide damage (not a disease) mosaics......

h) Leaf scorch around leaf margins and at leaf tip...... Physiological – water deficiency (not a disease)

30 Selected References

Atkinson, Thomas H., John L. Foltz, and Robert C. Wilkinson. 1988. Xylosandrus crassiusculus (Motschuylsky), an Asian ambrosia beetle recently introduced into Florida (Coleoptera:Scolytidae). Florida Department of Agriculture and Consumer Service Entomol- ogy Circular 310.

Daughtrey, M.L., C.R. Hibben, K.O. Britton, M.T. Windham and S.C. Redlin. 1996. Dogwood anthracnose: understanding a disease new to . Plant Dis. 80:349-358.

Davis, Michael and Roland R. Dute. 1995. Asian ambrosia beetles threaten southern orchards and tree nurseries. Alabama Agricul- tural Experiment Station Highlights of Agricultural Research 42:17-18.

Davis, M.A. and R.R. Dute. 1997. Fungal associates of the Asian ambrosia beetle, Xylosandrus crassiusculus. Proc. South. Nurs. Assn. Res. Conf. 42:106-112.

Engelhardt, George P. 1946. The North American clearwing moths of the family Aegeriidae, U.S. National Museum Bull. 190:1-222.

Fare, Donna C. 1999. Pruning landscape trees, shrubs and groundcovers. The University of Tennessee Agricultural Extension Service, Knoxville. PB 1619. 19 p.

Fare, Donna C. 1999. Planting wood ornamentals. The University of Tennessee Agricultural Extension Service, Knoxville. PB 1621. 7 p.

Fattig, P.W. 1947. The Cerambycidae or long-horned beetles of Georgia. Bull. 5. , GA: Emory University Museum. 48 p.

Gosling, D.C.L. and N.M. Gosling. 1977. An annotated list of the Cerambycidae of Michigan (Coleoptera): 2. The subfamilies Lepturinae and . Great Lakes Entomologist. 10 (1):1-37.

Hagan, A.K., B. Harding, C.H. Gilliam, J. Keever, J.D. Williams, and J. Eakes. 1998. Susceptibility of cultivars of several taxa to powdery mildew. J. Environ. Hort. 16:147-151.

Hale, F.A. and H. Williams 1998. Two-spotted spider mites. The University of Tennessee Agricultural Extension Service, Knoxville. SP 290-D. 3 p.

Hudson, W. And R. Mizell. 1999. Management of Asian ambrosia beetles, Xylosandrus crassiusculus, in nurseries. Proc. South. Nurs. Assn. Res. Conf. 43:198-210.

Johnson, W.T. and H.H. Lyon: contributing authors C.S. Koehler and J.A. Weidhaas. 1991. Insects that feed on trees and shrubs. 2nd ed., rev. Cornell University Press, Ithaca, . 560 p.

Jones, R. K. and R. C. Lambe. 1982. Diseases of woody ornamental plants and their control in nurseries. North Carolina Agricultural Extension Service, Raleigh. AG-286. 139 pp.

Kirk, H.B. and J.N. Knull. 1926. Annotated list of the Cerambycidae of Pennsylvania (Coleoptera). Canadian Entomologist. 58(1):21-26.

Lindquist, R. K. 1991. Identification of Insect and Related Pests of Horticultural Plants; A Pictorial Guide. T. R. Roll and H. K. Tayama (eds.). Ohio Florists’ Association Services, Inc. Columbus, Ohio.

Pless, Charles D. and W.W. Stanley. 1967. Life history and habits of the dogwood borer, Thamnosphecia scitula (Lepidoptera: Aegeriidae) in Tennessee. Journal of the Tennessee Academy of Science. 42(4):117-123.

Ranney, T.G., L.F. Grand, and J.L. Knighten. 1994. Resistance of Cornus kousa taxa to dogwood anthracnose and powdery mildew. Proceedings of Southern Research Conference. 39:212-216.

Schread, John C. 1965. Dogwood borer. Circ. 199. New Haven, CT: Connecticut Agricultural Experiment Station. 3 p.

Sinclair, W.A., H.H. Lyon, and W.T. Johnson. 1987. Diseases of Trees and Shrubs. Cornell University Press. Ithaca NY. 575 pp.

Solomon, J.D. 1995. Guide to insect borers of North American broadleaf trees and shrubs. Agric. Handbk. 706. , D.C: U.S. Department of Agriculture, Forest Service. 735 p.

Underhill, G.W. 1935. The pecan borer in dogwood. Journal of Economic Entomology. 28(2):393-396.

Windham, M.T. and R. Freeland. 1990. Disease and frost resistance and certain horticultural characteristics of ten dogwood cultivars. Tennessee Farm and Home Science 155:25-31.

Windham, M.T. and A.S. Windham. 1998. Chemical control of powdery mildew in flowering dogwood. Proc. of South. Nurs. Assoc. Res. Conf. 43:251-252.

Windham, M.T. and A.S. Windham. 1999. Enhancement of growth of flowering dogwood by using fungicides to control powdery mildew. Proc. of South. Nurs. Assoc. Res. Conf. 44:224-225.

Windham, M.T. and W.T. Witte. 1998. Naturally occurring resistance to powdery mildew in seedlings of Cornus florida . J. Environ. Hort.16:173-175.

Windham, M.T., E.T. Graham, W.T. Witte, J. L. Knighten and R. N. Trigiano. 1998. Cornus florida 'Appalachian Spring': a white flowering dogwood resistant to dogwood anthracnose. HortScience 33:1265-1267.

Windham, M.T., W.T. Witte, R.N. Trigiano, S. Schlarbaum, and A.S. Windham. 1997. Reactions of Cornus species to powdery mildew. Proc. of South. Nurs. Assoc. Res. Conf. 42:227-233.

31 Credit: Alan S. Windham

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PB1670-30M-12/00 R12-4910-19-001-01

The Agricultural Extension Service offers its programs to all eligible persons regardless of race, color, national origin, sex, age, disability, religion or veteran status and is an Equal Opportunity Employer. COOPERATIVE EXTENSION WORK IN AGRICULTURE AND HOME ECONOMICS The University of Tennessee Institute of Agriculture, U.S. Department of Agriculture, and county governments cooperating in furtherance of Acts of May 8 and June 30, 1914. Agricultural Extension Service 32 Charles L. Norman, Dean