Dogwoods for American Gardens (PB1670)

8/8/2019 Dogwoods for American Gardens (PB1670)

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Agricultural Extension ServiceThe University of Tennessee

PB1670

Dogwoods forAmerican Gardens


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About the Authors

Willard T. Witte , Associate Professor (retired), Dept. of Ornamental Horticulture and Landscape

Design, The University of Tennessee Agricultural Experiment Station, Knoxville

Mark T. Windham , Professor, Dept. of Entomology and Plant Pathology, The University of TennesseeAgricultural Experiment Station, Knoxville

Alan S. Windham , Professor, Dept. of Entomology and Plant Pathology, The University of TennesseeAgricultural Extension Service, Nashville

Frank A. Hale , Associate Professor, Dept. of Entomology and Plant Pathology, The University of Tennessee Agricultural Extension Service, Nashville

Donna C. Fare , Research Horticulturist, U.S. National Arboretum, Floral & Nursery Plants ResearchUnit, 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 andHarry E. Williams for their original publication entitled The Flowering Dogwood in Tennessee (TheUniversity of Tennessee Agricultural Extension Service Publication 589, 1969), which was used as a basefor this publication.

Appreciation is expressed to Hubert P. Conlon, Mark A. Halcomb, Carol J. Reese and StephenGarton for their peer review of this publication. We also thank Wanda H. Russell for editorial reviewand 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.

Dogwoods forAmerican GardensWillard T. Witte, Mark T. Windham, Alan S. Windham,

Frank A. Hale, Donna C. Fare and Wayne K. Clatterbuck

Cover Photo: Wayne K. Clatterbuck


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ContentsIntroduction ..................................................................4Facts and Legend ........................................................5Kinds of Dogwood ......................................................5

Cultivars of Flowering Dogwood....................8Cultivars of Kousa Dogwood ........................13Cultivars of Pacific Dogwood........................16Interspecific Hybrid Dogwoods.....................16

How to Grow the Flowering Dogwood ................17Soil ..................................................................17When to Plant................................................17How to Plant..................................................18Care After Transplanting .............................19Fertilizing.......................................................19Mulching.........................................................19Watering .........................................................20Pruning...........................................................20Will My Dogwood Bloom?.............................20

Integrated Management of Insects andDiseases of Flowering Dogwood ...........................21

Insects.............................................................21Dogwood Borer.........................................21Asian Ambrosia Beetle ...........................22Dogwood Club Gall..................................23Dogwood Twig Borer...............................23Dogwood Sawfly.......................................23Rose Leafhopper.......................................24Cottony Maple Scale................................24Walnut Scale ............................................24Two-spotted Spider Mite .........................25

Diseases..........................................................25Spot Anthracnose.....................................26Dogwood Anthracnose.............................26Dogwood Canker......................................27

Phytophthora Root Rot ............................27Powdery Mildew.......................................28Other Dogwood Diseases.........................28Leaf Scorch...............................................29

Summary ...................................................................29General Disease Management forDogwoods Growing in Landscapes ......................29Key to Diseases of the Flowering Dogwood ......30Selected References ..................................................31

Web SitesThe University of Tennessee Dogwood Research Group maintains a Web site (dogwood.ag.utk.edu) that is

devoted to cultivation and growth of flowering dogwoods. The site contains descriptions and photographs of Cornus species, dogwood cultivars, diseases and insect pests. The site is kept up to date concerning newdisease epidemics and outbreaks of insect pests, has a FAQ (Frequently Asked Questions) section andmaintains a forum where individuals can ask/or discuss problems they are having with their dogwoods.

A series of publications about site and tree selection, tree maintenance and tree care for urbanlandscapes are available at The University of Tennessee Agricultural Extension Service Web site(www.utextension.utk.edu/publication/forestry.htm).

Credit: Wayne K. Clatterbuck


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IntroductionSeventeen species of dog-

wood are native to the UnitedStates, with about 50 through-out the northern hemisphere of the world. The familiar specieswe call flowering dogwood,Cornus florida , is related tomany others. This publicationdiscusses those of ornamentalvalue. Most dogwood species areeither shrubs or small trees andcan be easily divided into twomain groups: those with redfruit (occasionally yellow) andthose with blue-black (some-times whitish) fruit.

Most of the red-fruitedspecies have large showy bractssurrounding a terminal clusterof tiny true flowers. These large-bracted dogwood species are alltrees, except for the bunchberry,a low-growing ground coverfound in northern climates. Mostof the blue-fruited species areshrubs and all have whitish,flat-topped flowers of tinyclusters called cymes or umbels.These flowers are without theshowy bracts.

The native floweringdogwood, Cornus florida , is oneof the most beautiful small treesin the world, with ornamentalvalue in all seasons. Nearly allflowering dogwoods in the wild

have white bracts, but a rarepink form does occur naturally.

Modern selections grown by

nurseries have been chosen forlarge, white, clear pink or darkred bracts; variegated leaves;double bracts; weeping or dwarf growth habit and other specialcharacteristics.

The beauty of floweringdogwood is not limited to aparticular season or a singlepart of the tree. Most selectionsbegin with a glorious floraldisplay in April, followed byattractive green foliage arrayedon horizontally spreadingbranches. A show of bright redberries appears in late summerand is accompanied by earlydevelopment of dark red foliage.The beauty cycle ends with aninteresting winter silhouette of

horizontal gray branches

tipped with upturned, button-like flower buds.In addition to its beauty,

the dogwood is an importantfood source for birds and wild-life. Berries of the floweringdogwood are eaten by manyspecies of songbirds and smallmammals from August untilthey are gone, often as late asFebruary or March.

This publication providescultural information andornamental characteristics tohelp you select dogwoods foryour landscape and how tomaintain them in good health.If you have any questions,contact your CooperativeExtension Service.

Dogwoods forAmerican Gardens

Red fruit of . Credit: Mark T. Windham


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Facts and LegendThe name dogwood appar-

ently originated in Europe. Thebark of one of the Europeanspecies was boiled in water andused for washing dogs sufferingfrom mange. Most authoritiesbelieve that dogwood is a corrup-tion of dagwood , with dag beingan old name for a meat skewer.The hard wood of this species isuseful for that purpose.

The name dogwood is lessinspirational than the legendthat the dogwood once grew as atall, straight tree and was usedfor timber. But when the woodwas used to make the cross of Calvary, Jesus was so movedthat he promised the tree wouldnever again grow large enoughto be employed for such a pur-pose. It is also said that thebracts of the dogwood are set inthe shape of a cross and bearnail marks of the Crucifixion,and the red leaves in autumn

have been associated with Jesussblood on Calvary. The dogwoodalso served in the field of medi-cine at one time. Dogwood barkwas one of many barks used as afever medicine before quininecame into general use.

Of more importance is therole the dogwood once played inthe textile industry and insports. The wood from dogwoodwas used to make shuttles forweaving machines because of itsvery heavy, fine-grained andvery hard properties, and becausewith wear it becomes extremelysmooth and resistant to abrasion.

The same qualities made ituseful for golf clubs, jewelersbenches and as wedges forsplitting logs.

Given time and favorablegrowing conditions, some dog-woods attain large stature.Currently, the largest knowndogwood tree in the UnitedStates is a Pacific dogwood,

Cornus nuttallii , in Clatskanie,OR that is 60 feet tall with a58-foot branch spread and atrunk diameter of more than 3feet. The largest floweringdogwood is in Sampson County,NC and is 31 feet tall with a 48-foot branch spread and a trunkdiameter of just greater than 3feet. Champion trees often donot retain their title long due toloss of branches from disease orstorms or from being outgrownby competitors.

Kinds of DogwoodDogwoods are in the genus

Cornus within the Cornaceaefamily. The most common orna-mental and native species of Cornus are described in thissection. Those native to theUnited States are marked with asingle asterisk (*). Hardiness isindicated by the USDA planthardiness zone (Figure 1).

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

Average AnnualMinimum Temperature

Temper at ure ( C) Tem pe rat ur e ( 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 251.6 to -1.1 35 to 304.4 to 1.7 40 to 35

4.5 and Above 40 and Above


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'Aurea', Cornelian Cherry. Credit: Willard T. Witte

, Pacific Dogwood. Credit: Mark T. Windham

*Cornus florida , Flowering Dogwood.Zones 5-9. Native to the EasternUnited States from the Gulf of Mexico and central Florida to eastTexas, Oklahoma and Arkansas toChicago and southern New England.Typically grows 12-20 feet tall with a6-12 inch trunk diameter, butsometimes larger. Considered a short-to medium-lived tree in landscapes,but may live 100 years on good sites.Blooms in mid-spring as leaf budsbreak. Four showy bracts, notched atthe tip, rapidly expand and turnwhite, centered by a cluster of 20 ormore tiny true flowers with fourpetals, four stamens and one stigma.Scarlet oblong-oval berries in the fallare valued food for birds and wildlife.A few yellow-fruited forms occur. Thedistinctive alligator bark is brokeninto small squarish blocks. Buttonlikeflower buds occur on upturnedhorizontal branches in winter. Thereare many selections and cultivarschosen for superb ornamentalcharacteristics.

Cornus kousa , Japanese or Chinese orKousa Dogwood. Zones 4-8. Native toChina, Japan and Korea, this tree willgrow in the U.S. wherever our nativeflowering dogwood grows. Blooms havefour-pointed flower bracts about aslarge as those of flowering dogwood,but appear a few weeks later. Thefoliage develops before the bractsappear. The long-lasting bracts aredisplayed above the leaves on long

flower stems. The aggregate fruitlooks like a rosy-red golf ball, the sizeof a nickel or larger, and containsseveral seeds embedded in pulpyorange flesh. The pulp is said to beedible when ripe. As fruits gain inweight and size, they hang under thebranches on long stalks likeornaments. Borers or diseases rarelytrouble kousa dogwoods. The averagekousa dogwood tree has to be a fewyears older than comparable floweringdogwoods to develop a heavy bloomdisplay. Some mature kousa treeshave beautiful flaking mottled barkpatterns on a smooth trunk. Theflower bracts of some kousa dogwoodsmay become tinted with pink whenthe plant experiences cool weather, isunder stress or when the bracts age.

Varieties are currently being selectedthat are considered truly pinkflowering. Nursery producers are

becoming more experienced withgrowing kousa dogwoods, and bettertypes are being evaluated.

*Cornus nuttallii , Pacific Dogwood.Zones 6b-9a. The native range is abroad band along the West Coastfrom about San Francisco, excludingthe Imperial Valley, northward intoBritish Columbia. Grows taller andmore upright than floweringdogwood. Blooms are also larger andtypically have six bracts (un-notched)instead of four. May re-bloom in latesummer. Flower bud scales (bracts)do not enclose the over-winteringflower cluster. Bark remains smooth.Unfortunately, it does not seem tothrive in the East. Hybrids between

Pacific dogwood and floweringdogwood are known.

Cornus mas , Cornelian Cherry.Zones 5-8. A hardy European speciesthat seems to be at the southernlimit of its heat tolerance in the mid-South, where it frequently presents apoor appearance by the end of summer. It grows as a small tree ormulti-stemmed shrub up to 15-20feet tall. Cornelian cherry blooms invery early spring, before forsythia,with many clusters of small, yellow,bractless flowers. The oblong cherry-like fruit is both ornamental andedible and may be used forpreserves. A few cultivars areavailable in the trade.


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Red twigs on , Red OzierDogwood. Credit: Willard T. Witte

, Pagoda Dogwood.Credit: Willard T. Witte

Foliage of 'Variegata' orwedding cake tree.Credit: Willard T. Witte

Cornus officinalis , Japanese Cornel.Zones 5-8. This shrub or tree is verysimilar to Cornelian cherry, butgrows larger (to 30 feet), and has theadded attraction of interestingexfoliating bark that flakes off tocreate gray, brown and orangepatches on mature trunks. Flowersare similar to Cornelian cherry butbloom a week earlier, well before theleaves emerge. The edible butflavorless scarlet berries ripen afterCornelian cherry.

*Cornus sericea (formerly C.stolonifera ), Red Osier Dogwood. Zones2-7. Native stands grow in moist-to-wet sites from Newfoundland toManitoba, south to Virginia andKentucky, west to Nebraska, but havea wider adaptability in landscapes.This multi-stemmed shrub grows to 7feet and spreads slowly byunderground stems, making thickets.Flat clusters of chalky white flowersform a cyme that blooms in latespring, often followed by white berries.Varieties are available with bright red,olive-yellow or green stems for wintercolor. 'Silver and Gold' has whitevariegated leaves and yellow stems.Again, these plants are grown forwinter bark color and old branchesshould be pruned to the ground everyyear or two to induce a good growth of new, brightly colored branches.

*Cornus alternifolia , PagodaDogwood. Zones 3-7. This small,

widespreading tree is native fromNew Brunswick to Minnesota, southto Georgia and Alabama, and westto Missouri and Arkansas. Pagodadogwood has a strongly horizontallybranching habit and reaches abouthalf the size of flowering dogwood.Yellowish-white flowers in anupright cyme bloom in mid- to latespring and are very fragrant. Theseare followed by fruit that changesfrom green to red to blue-black, onred stalks. Unlike most dogwoods,this species has alternate leavesinstead of opposite, though this maybe hard to see because leaves tendto be clustered near the tips of thebranches. A rare white variegatedform, 'Argentea', has smallerleaves. An antique common name

was pigeonberry, apparentlybestowed during the era of thepassenger pigeon.

*Cornus racemosa , Gray Dogwood.Zones 4-8. A shrubby tree to 15 feet,found on moist sites from Maine toManitoba, south to Florida, and westto Missouri and Oklahoma. It tendsto grow in colonies due to asuckering habit, so it is often bettersuited for wildlife and native plantgardens than well-groomedlandscapes. White flower panicles inmid-spring are followed briefly bywhite berries. Red fruit stalksremain ornamentally interestinguntil fall. A recent selection isnamed 'Jade'.

*Cornus amomum , Silky Dogwood.Zones 5-8. This shrub ranges fromMaine to Indiana, south to Georgiaand Florida, and grows to 9 feet.White flower clusters form a flat-topped cyme that blooms in earlysummer, followed by blue berries.While considered too coarse andstraggling for most gardens, in theproper setting it has a place, as in anative plant garden or wildlife garden.

Cornus controversa , Giant Dogwood.Zones 4b-8. Native to China and

Japan, this is the largest and fastestgrowing of the dogwoods, capable of attaining 60 feet. Giant dogwooddevelops distinctly spreadinghorizontal branches at an early age.Creamy white flower clusters form a3-7 inch flat-topped cyme in earlysummer that are showy and may befollowed by bluish-black berries. The

large paired leaves may turn reddishor purplish in autumn. It is rareoutside of arboretums. A beautifulvariegated form exists.

Cornus alba , Tatarian Dogwood.Zones 2-7. The native range is Siberiathough northern China to Korea. Thislarge shrub, multi-stemmed to thebase, grows to 9 feet unless cut back.Since it is grown primarily for thewinter display of bright coral-redstems, which is brightest on newgrowth, the old dull branches shouldbe cut every spring to ground levelbefore growth starts. This also keepsplants to a manageable size. Tatariandogwood has yellowish-white flowersin 1 1/2 to 2-inch cyme with flat-toppedclusters in late spring, often followed

by white berries. Several varietieshave variegated foliage. 'Argenteo-marginata' has an irregular creamy-


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White fruit onDogwood. Credit: Willard T. Witte

white margin around a leaf center of subdued grayish-green. On'Gouchaltii' and 'Spaethii' themarginal leaf variegation is yellow.Either can add a nice spot of lightcolor to a summer garden. Someafternoon shade is beneficial.

Cornus sanguinea , BloodtwigDogwood, is a European cousin of Tatarian dogwood. The rough-looking, suckering shrub is rarelyrecommended for ornamental useother than for its purplish-red wintertwig color.

*Cornus obliqua , Pale Dogwood, and*Cornus asperifolia , Roughleaf Dogwood, are shrubby cousins of silkydogwood and occur in roughly thesame range and habitats. They differin minor botanical characters such astwig color, pith color and hairiness(pubescence) of the leaves.

*Cornus canadensis , Bunchberry.Zones 2-6a. This subshrub (to 9

inches tall) spreads by woodyrhizomes forming a ground cover inthe woods. The white bracts and red

berries are quite similar to floweringdogwood. Bunchberry grows fromAlaska, Canada and Greenland andcan sometimes be found at highelevations as far south as WestVirginia. A challenging groundcoverplant for garden experts, it requiresshade, moisture, an organic soil andcool temperatures.

Cornus macrophylla , Bigleaf Dogwood. Zones 5-7. Rare in theU.S., this small tree ranges fromthe Himalayas to China and Japan.The tree grows to 35 feet, with largeleaves 4-7 inches long. Flowers areyellowish-white in 4-6 inch loosepanicles in late summer followed bybluish-purple berries. This species isvirtually unknown outside of arboretums in this country.

*Cornus baileyi , Bailey dogwood, isa non-stoloniferous cousin of redosier dogwood and occurs in thesame range. The other maindifference is a distinctly woolypubescence of young shoots and theundersides of leaves. Somebotanists ascribe it to be asubspecies of C. sericea .

Cornus walteri , Walter dogwood, ishardy to zone 5 and is native tocentral China and Korea. It has atree type stature, growing to 30-40feet high and wide with thealligator bark typical of our nativeflowering dogwood. The 2-3 inch flat

cyme is formed by white flowerclusters in mid-summer, followed bysmall black berries that mature inearly fall. This species deserves widertesting and use.

Botanical manuals describe manymore species of native and exoticdogwoods, but most are of lesserornamental value than those describedabove or are of only local interest.

From the species of Cornusmentioned above, one can see thatthe native flowering dogwood is justone member of a large and diversegenus. It is the dogwood of interestto most gardeners, and isunquestionably beautiful, a smalltree for all seasons. However, manyof the other species and their

cultivars have special ornamentalmerit of their own and can add tothe diversity of our landscapes.

The word 'cultivar' is ahorticultural term for 'cultivatedvariety,' as distinguished from abotanical variety ('varietas') or form('forma') that occur naturally in thewild. A cultivar name should alwaysbe enclosed in single quotationmarks. The next section containscapsule descriptions of the mostimportant and available cultivars forseveral species.

Cultivars of Flowering Dogwood,Cornus florida

Several botanical varieties andforms of flowering dogwood havebeen grown in gardens over theyears; more than 80 cultivars havebeen developed from either seed orsports (mutations). Newer cultivarscontinue to be developed. Selectionshave been made for pink or red bractcolor, ability to bloom at a youngage, large bract size, variegatedfoliage, weeping or dwarf habit of growth and disease resistance.

Pink and Red FloweringDogwoods : The first record of apink flowering dogwood in the wildwas by Mark Catesby of Virginia in1731. Occasional finds of wild pinkdogwood still occur to this day.Most pink and red dogwood will notcome true from seed and areusually propagated by bud grafting.Unnamed selections are oftenmarketed under the name ' Rubra',which seems to be applied to anypink type not identified as aspecific variety. Most pink and redcultivars are not as winter hardyas most white cultivars, nor arethey as heat tolerant, except for afew selections originating in theDeep South. New foliage oftencomes out in the spring with adistinct red tinge, and usuallydevelops brilliant red fall color.

Variegated Foliage : Variegation isexpressed when mutations occur thatblock development of chlorophyll inone or more layers of leaf tissue. Inthese cases, the variegated part is

usually cream, yellow or golden dueto the xanthophylls and carotenesstill in the tissue. If formation of

Bailey Dogwood.


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yellow pigment is also blocked,variegation will be white. Sinceseveral layers of leaf tissue may beaffected independently of each other,it is possible to have multicolorvariegations, expressed as centralblotches, marginal bands or irregularsplashes along leaf veins.

Many variegated cultivarsmaintain their showy leaf variegation pattern longer intosummertime when grown in full sun.In the shade, green pigment mayeventually develop throughout theleaf blade, resulting in fading of thevariegation pattern. Becausevariegated-leaved plants have lesschlorophyll, they grow slower and setfewer flower buds than green-leavedplants. White sectors of variegationare more susceptible to leaf scorchwhen plants are stressed than yellowor pale green sectors. Variegatedparts of leaves are the first to showfall color, as the developinganthocyanin pigments are notmasked by chlorophyll. Many typesof leaf variegation tend to beunstable and one or more shootsoccasionally revert to all green.Green shoots are more vigorous andmust be immediately and entirelypruned or they will overgrow andcrowd out the desired variegatedpart of the plant.

Novelties and SpecialCharacteristics : Some floweringdogwood cultivars are grown for the

unusual habit of growth (dwarf,weeping, fastigiate or columnar), leaf shape (willowleaf), yellow berries,double flowers, fragrance or largerthan normal berries or flowers.These novelties add interestingaccents to many landscapes.

Southern vs. Northern Origin :Many selections found in the wildhave been propagated and broughtinto cultivation. In the capsuledescriptions below, the origin is notedwhen known. The origin is importantbecause flowering dogwood is closelyadapted to its ecological niche,especially in regard to winterhardiness, bloom time in the springand acclimating for winter dormancyin the fall. A southern ecotype grown

in the north may winterkill due tolack of hardiness, bloom too early inthe spring and thus have flowers

blasted by killing frosts, and not godormant soon enough in the fall tosurvive killing fall frosts. Northernecotypes grown in the deep South maynot grow and bloom well and maysuffer from heat stress. These factorsare obviously more critical at theextreme southern and northern limitsof the range where flowering dogwoodcan be grown. Also in the north, leaf buds may be winter-hardy whileflower buds may be damaged fromsevere cold, so good flower budhardiness is sought in northerncultivars. Listed below are capsuledescriptions of some of the moreimportant modern cultivars of flowering dogwood in the nurserytrade, parks and arboreta.

'Appalachian Spring' . This newcultivar is the only floweringdogwood that is resistant to dogwoodanthracnose ( Discula destructiva ). Ithas apple green leaves about onethird larger than the species, andsculpturally curving white bracts,followed by the typical red berries.Red to purple fall color.Unfortunately, this cultivar issusceptible to powdery mildew.

'Autumn Gold '. White bracts.Recent introduction from Winchester,TN with conspicuously golden falland winter bark color.

'Cherokee Brave' . A recentintroduction from Winchester, TN

with good resistance to powdery

mildew. Red blooms have a palercenter. New growth with reddishleaves turning green at maturity.

'Cherokee Chief' . Considered as oneof the best red-flowering dogwoodson the market today. Deep rose-redblooms and reddish leaves on newgrowth. Vigorous grower with centralleader and uniform branching.

'Cherokee Daybreak' . Improvedwhite-flowered variegated selectionresists scorch in full sun. Leaves havea blotched green and gray-greencenter with a wide irregular marginof creamy white that turns pink incooler fall weather. White bracts.Susceptible to powdery mildew.

'Cherokee Princess' . Selected inMayfield, KY for its large whiteblooms exceeding 4 inches indiameter. Very floriferous and bloomsat an early age. Highly resistant tospot anthracnose.

'Cherokee Princess'. Credit: Willard T. Witte

'Cherokee Brave'.Credit: Willard T. Witte


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According to the most recentestimates, there are about 80 cul-tivars of the flowering dogwood,Cornus florida , that have beennamed. This partly reflects themany decades that nursery pro-

ducers have been growing this species. Some of theolder cultivars, while documented in the horticulturalliterature, may no longer exist; that is, they have notbeen perpetuated in nursery production and have diedout of landscapes.

There are about 70 cultivars of Cornus kousa , theChinese dogwood. Many of these are of recent origin,owing to a surge of interest in this species. Many newerChinese dogwood cultivars have yet to be tested foradaptation and performance over a wide range of climates and sites, but some are destined to add newinterest to our gardens.

Until recently, nearly all dogwood cultivars cameto be named because someone noticed somethingdifferent and worthwhile about a particular individualdogwood seedling and then decided to propagate it andname it. Since dogwood is an obligate outcrosser (itdoes not pollinate its own flowers), there is always somegenetic variability existing in every new crop of seed.Plant enough seed from enough different sources and

some of the possibilities will be expressed in a few of the seedlings, such as a dwarf or weeping or fastigiate(columnar) habit of growth, bract color, bark color,variegated foliage of several different patterns, abilityto bloom at an early age, insect or disease resistanceand so on.

Dogwoods may also change because of theexpression of somatic mutations, which is a randomchange in a gene that may occur once in every severalmillion cell divisions. For example, if a mutation occursthat affects the formation of chlorophyll, and thismutation just happens to be located in a layer of leaf tissue of an expanding bud or shoot, then it is possiblethat a bud sport or branch sport might arise withvariegated leaves on a tree that otherwise has allgreen foliage. This does not happen very often, but ona nursery with hundreds of thousands of dogwoods inproduction, it will likely occur. It takes an alert eye topick out mutations and a wise nursery producer willoffer a bounty to workers who identify one.

Up until the last decade, there was no purposefulbreeding of dogwood to produce new cultivars, unlikefield and forage crops where breeding programs have

been going on for almost a century. Then Dr. ElwinOrton of Rutgers University in New Jersey beganworking with dogwood in his ornamental plant-breedingprogram. In the early 1990s, he patented and releasedthe Stellar series, which are hybrids between Cornus

florida and Cornus kousa . With one exception ('RuthEllen'), these have astronomy-based names such as'Aurora', 'Constellation', 'Stellar Pink', etc. Dr. Ortonhas also made crosses with Cornus nuttalli , and someof the resulting progeny are out on trial prior to namingand release. Dr. Orton also bred and patented anunusually vigorous Cornus florida with fruit nearlytwice normal size and named it 'Wonderberry'.

Researchers at The University of TennesseeInstitute of Agriculture (UTIA) began searching fordisease-resistant flowering dogwoods in the early1990s. They discovered several in the wild andpropagated them for further testing. One, named andreleased as 'Appalachian Spring', is highly resistantto dogwood anthracnose. It is currently being increasedand should be on the market by 2005. Then in themid 1990s, an epidemic of powdery mildew severelyimpacted dogwood seedlings in nurseries all over theeastern United States. UTIA scientists searchednursery fields for resistant seedlings and rescued about80. After extensive testing, three of these are beingnamed and patented: 'Jeans Appalachian Snow','Karens Appalachian Mist' and 'Kays AppalachianBlush'. They are being increased and should beavailable for purchase by 2007.

UTIA researchers currently have a dogwood-breeding program aimed at combining resistance to thetwo diseases (anthracnose and powdery mildew) in newplants. They have even worked out methods to employhoneybees, which normally do not visit dogwood flowers,to achieve cross-pollination. Hundreds of seedlings havebeen produced and are being tested, and breedingorchards of dogwood have been planted to produce seed.

The same UTIA scientists are screening Cornus

kousa seedlings for heat and drought tolerance. Anumber of these seedlings have been selected and arebeing placed in an evaluation program.

UTIA

'Appalachian Spring' is a flowering dogwood cultivar that is resistantto dogwood anthracnose.Credit: Mark T. Windham


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'Cherokee Sunset' . Good red bractsand strongly variegated foliage. Leaveshave a broad irregular yellow marginthat resists scorch in summer heat.Fall color ranges from pink on themargins through red and purplecenters. Resistant to spot anthracnose.This unique dogwood was consideredstable enough for introduction in 1979,eight years after discovery.

'Cloud 9' . Introduced from Chase,AL in 1951. Wide, overlappingwhite bracts in profusion. Blooms atan early age. Due to heavyflowering and fruiting, it is slowergrowing than most dogwoods. Avery similar cultivar, 'Barton',selected in 1956 in Birmingham, ALbecame mixed with 'Cloud 9' in thetrade and DNA fingerprinting showsplants currently offered under eithername are the same.

'First Lady' . Introduced fromMcMinnville, TN in 1969. Thisvariegated cultivar has white blooms,but is not a heavy bloomer. The leaveshave yellow variegations splashed overa light and dark green background. Ittends to scorch less than plants withwhite variegations. Leaves may turnall-green in summer if grown in toomuch shade. It is highly resistant tospot anthracnose. A less vigorouscultivar, but a beautiful specimenwhen well cared for.

'Fragrant Cloud' . Introduced from

Gatlinburg, TN in 1968. Said to havea profusion of white flowers and aslightly fragrant scent like gardenia.This vigorous grower is seldomoffered. Resistant to spot anthracnose.

'Green Glow' . PP#4444. Introducedfrom Portland, OR in 1973. This is amutation of 'Welchii' with a slightgolden vein centered in dark greenleaves. Upright growth habit. Rare.

'Golden Nugget' . Introduced fromWinchester, TN. Similar to 'FirstLady' and 'Hohmans Golden', thiswhite-bracted cultivar has yellow leaf margins and tends to turn all greenin the shade.

'Hohmans Golden' . Introduced

from Wayne, NJ in 1964. Green andyellow variegated foliage and whiteblooms. Named after Henry J.

Hohman, founder of the KingsvilleNursery in Maryland.

Howell Hybrids . Not a cultivarname, but refers to a group of about10 numbered seedlings grown byHowell Nursery, Sweetwater, TNprior to 1960, from a supposed crossof a pink tree from the North and apink tree from the South ('Prosser').Seedling #1 became 'Cherokee Chief'and #2 or #3 became 'SweetwaterRed'. 'Cherokee Brave' is assumed tobe a seedling of 'Cherokee Chief'.

'Jeans Appalachian Snow' . Anew, powdery mildew-resistantcultivar developed by the TennesseeAgricultural Experiment Station.Very large, pure white, blockybracts, similar in size to 'CherokeePrincess', are overlapping. Even theindented cleft at the tip of the bractlacks pigmentation. Red berries;good fall color.

'Karens Appalachian Blush' . Anew, powdery mildew-resistantcultivar developed by the TennesseeAgricultural Experiment Station.The bracts are long and floppy,delicate in appearance, and do notoverlap. Bracts are white with a palepink blush developing on themargins. Red berries; good fall color.

'Kays Appalachian Mist' . A new,powdery mildew-resistant cultivar

developed by the TennesseeAgricultural Experiment Station.Creamy white bracts that slightlyoverlap. Cleft at the tip of the bractis flat and deeply pigmented. Redberries; good autumn color.

'Mystery' . Introduced fromWinchester, TN in 1965. Thisdwarfish compact tree has bloomswith large white bracts, butoccasionally some bracts developpink blushes or reddish blotches.Drought-tolerant. Rare.

'Ozark Spring' . White-floweredcultivar introduced in Kansas forbetter flower bud hardiness. Whitebracts and wine-red fall color.Selected from among 125 plantsgrown from seed collected inCrookston Hill region of Oklahoma.Has flowered after sustainingtemperatures of 30 degrees F.

'Cherokee Sunset' (left) and 'Cherokee Daybreak' (right)Credit: Willard T. Witte

'First Lady'.Credit: Willard T. Witte


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'Pendula' . Weeping form withdrooping bracts and white flowers.May come true to type from seed.Original clone, found wild inMaryland, was raised in aPhiladelphia nursery before 1880.Not a particularly attractive weepingtree. There may be several weepingforms in the trade under this name.

'Pink Sachet' . Similar to 'CherokeeChief' but with pronounced flowerfragrance. Assumed to be a seedlingof 'Cherokee Chief'. Uncommon.

'Plena' . An older, white-bractedcultivar with semi-double flowers of medium size. Blooms about twoweeks later than single-floweredtypes, thus escaping late spring frostdamage. Blooms last longer thansingle-flowered dogwoods, which tendto drop bracts as soon as berries set.Does not set fruit. Very prolificbloom, but visual impact reduced assome flowers hidden by developingfoliage. Appears to be immune tospot anthracnose.

'Pluribracteata' . A double formwith 7-8 and often more large bractsand true flowers more or lessaborted. Blooms 7-10 days later thanmost other flowering dogwoodcultivars, thus escaping spring frostdamage. Does not set fruit. Someauthorities lump 'Plena' under thisname. There may be several double-flowering forms.

'Poinsett' . Golden yellow berries inthe center of a group of red autumnleaves are said to resemble apoinsettia. Compact and vigorousgrowth with long, pointed leaves.

'Prosser' . Of historical significanceas the progenitor of most of ourcurrent red-flowered dogwoodcultivars. Found by Bruce Howell,Knoxville, TN around 1920, onproperty owned by Brown Prosserabout three miles from HowellNursery. Poor growth habit. Flowershave a good dark red color butinferior conformation. New leavesdark reddish green.

'Purple Glory' . New foliage maroon

to purple suffused over a light greenbackground. Flower bracts dark red.Susceptible to dogwood canker.

'Pygmy' . A slow-growing plant,reaching perhaps 4 feet in eightyears, which generally produces anabundance of small, 1 1/2 -inchflowers. Uncommon.

'Rainbow' . White flowers, and themost brilliant variegated foliageimaginable under protectedconditions. Bright deep yellow andgreen leaves in spring and summerturning to pink, red and blue-lavender in fall. Red berries. Leaveshave a wide, irregular, creamy

yellow margin and a green center.The lighter margin overlays portionsof the green tissue extending to thecenter of the midrib, creating yellow-green splotches. Subject to scorch inexposed sunny sites.

'Red Beauty' . A semidwarf compacttree with many small red blooms.Flowers at an early age. From acontrolled cross in the RutgersUniversity, NJ breeding program.

'Roberts Pink' . Apparently a choicepink-flowering dogwood originatingin southern Louisiana in the early1900s. A vigorous-growing, pinkdogwood adapted to the Deep South.

'Royal Red' . New foliage opens

blood red, then becomes greenish andturns bright red in fall. Flowers aredeep red and very large. Uncommon.

'Rubra' . First described as abotanical variety in 1770. Later,properly classified as a forma in1915. This name is not valid at thecultivar level, but representsbotanical forms with washed outpink to dark red flowers on differenttrees. First discovered in Virginia,but occurs more widely, thoughinfrequently, in the wild. It is abeautiful plant when properly grown.The flowers are not as cold hardy oras heat tolerant as the white form.Tends to open a few days later than

typical white form.

'Salicifolia' . A small, rounded tree;the leaves are very narrow andwillow-shaped. It has a fine textureand does not flower well.

'Spring Song' . A northern type of 'Rubra' with especially large flowersof rich, rosy red.

'Springtime' . The original tree wasselected from a planting in SpringGrove Cemetery, Cincinnati, Ohio in1957. Large, white, overlappingbracts, 5 inches across from tip totip. Wide-spreading growth habit;undersides of the leaves turn adistinctive purplish color in the fall.Highly resistant to spot anthracnose.

'Sterling Silver' . An excellent whitevariegated dogwood that does not

'Rubra'. Credit: Willard T. Witte


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or deciduous in Zone 6. Narrowglossy leaves droop distinctly infall and winter. Purple to winewinter foliage color. This recentintroduction from China may beelevated to species rank bybotanists. Winter hardinessunknown, but probably less thanmost C. kousa. Definitelyrecommended for trial in climatespreviously considered too warm forgood performance of most kousas.Blooms later than most C. kousa .

'Autumn Rose' . Long, drooping,wavy (almost ruffled) leavespresent a different, yet distinctiveappearance. A small upright treeselected for its unusual creamy,pale greenish-white bracts in earlysummer. Fall color ranges frompink to light red. Sparse productionof fruit.

'Beni Fuji' . Small, vase-shaped treewith a multitude of small, starry-pink bracts. Slightly distortedleaves smaller than normal, reddishnew growth.

'Big Apple' . Large spreading treewith heavy-textured dark greenleaves and very large fruit, hardy to5 degrees below zero F.

burn in full sun. Slower growingthan normal, developing a layeredeffect as it ages.

'Stokes Pink' . Pink bracts on amedium-size, vigorous, upright tree.Good in warm climates.

'Sweetwater Red' . Selected in1954 by Howell Nursery, Knoxville,TN and introduced in 1961. Deepred flowers and reddish foliage,good red-purple fall color, andmoderately disease resistant. SeeHowell Hybrid listing.

'Weaver' . A 1941 Florida selectionwith stronger and larger bronzynew foliage, and larger and morenumerous blooms. Well-suited forFlorida, as it does not require aslong a period of chilling toovercome winter dormancy as morenorthern ecotypes.

'Welch Bay Beauty' . Particularlyhandsome double form with flowerslike gardenia, seven sets of whorledwhite bracts 4.5 to 5.5 inches indiameter. Lower bracts shed beforethose above. Trees bloom at an earlyage and blooms last longer than mostdogwoods. Found in the wild inBaldwin County, AL in 1972. Performsbetter in Deep South. Holds leaveslonger and develops good autumncolor; 20 feet tall. Probably not ashardy as most 'Pluribracteata' forms.

'Welchii' . Perhaps the oldestselection with tri-color variegation,it has leaves that are a combinationof green, creamy white and pink.Best in partial shade to avoid leaf scorch. Spectacular rose red to redpurple fall color, white bracts. Doesnot perform well in the South andgenerally should be planted inpartial shade. Sparse bloomer.Sometimes reverts to green foliagetype and these reversions should bepruned immediately as they occur.A selection called the 'KingsvilleForm' has better color and is abetter grower.

'Welchs Junior Miss' . Ratherattractive, large-flowered form withdeep pink bracts grading to whitish

in the center and small white bracttips. Found as a wild plant in 1957in Mobile County, AL. A rather

attractive small-flowered form thattends to have sparse bloom.Resistant to spot anthracnose. Holdsits color in the Deep South. Requiresless chilling than other dogwoods tobreak winter dormancy. Vigorousgrower with red coloring of newgrowth. Blooms late in season.

'Wonderberry' . Unusually vigorous,dark green leathery leaves, brilliantred tubular fruit about twice-normalsize, and abundant white flowers inearly spring. From a controlled crossof the breeding program at RutgersUniversity, NJ.

Worlds Fair' . Large white bracts.Blooms at an early age, stockytrunk, large-diameter limbs, droughtresistant, hardy to 7 degrees F.

'Xanthocarpa' . White blooms andyellow fruit. Botanically this is a

forma of the species. Since morethan one genotype has been placedunder this forma , the name isinvalid at the cultivar level. Severalclones are in cultivation (see'Poinsett'). Stems show no trace of red pigment, being devoid of anthocyanin pigments.

Cultivars of Kousa Dogwood,Cornus kousa

'Aget '. Chance seedling. Large bracts,re-blooming or long-blooming bractsmay persist from June to September.

'Akabana' . Originated in China.Growth habit is consistent with thespecies. Said to have perfect pinkbracts, but the warmer the weather,the poorer is the expression of redpigment. There is some question asto whether this is distinct fromother pink-blooming cultivars, as'Akabana' is the Japanese genericname meaning red flower that isapplied in Japan to all pink-flowered forms.

'Angustata' (aka 'Augustifolia')and sometimes ascribed to the

species Cornus capitala by somebotanists. Evergreen in Zone 7 orwarmer climates, semi-evergreen

'Augustata'.Credit: Willard T. Witte

'Big Apple'.Credit: Willard T. Witte


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all summer. White bracts, vigorousgrowth, radiant pink and burgundyfall color.

'Satomi' . Pink-flowering form namedin Japan and introduced to Europeand U.S. in the 1980s. Red pigmentin leaves and branches. Excellent fallcolor. Hardy to -20F. This is thecorrect name for 'Rosabella' and 'NewRed'. Best bract color in light shadeand cooler climates. Disease-prone.

'Snowboy' . Leaves pale gray-greenwith regular to irregular white margin2 to 5 mm wide and with occasionalsplashes of yellow-green, pink or palergray-green variegation throughout.Not a particularly stable form and notparticularly vigorous. Slow-growingand shrubby. Foliage may scorch infull sun. Introduced in late 1970s byBrookside Gardens from Japan.

'Speciosa' . Very dark green leavescurl slightly at margins, impartingan interesting bicolor effect due tothe lighter undersides. Large whitebracts. Hardy to -15 F. Slow-growing.

'Square Dance' . Upright growthhabit with flowers most visible fromabove. Hardy to 5 degrees below zeroF. Named for the square pattern of the bracts. Good fall color.

'Steeple' . Upright growth habit,foliage deep green, glossy, with goodfall color. 1961 source from Marthas

Vineyard, MA.

'Summer Majesty' . Long bloomingseason with bracts like snow banks,which after 3-4 weeks acquire a pinkblush for another month. A maturetree would be 20-25 feet.

'Summer Stars' . Heavy-bloomingvariety retaining flowers six weeks intosummer. The fruits supposedly developwith the bracts still present. Robustdark green foliage changes to reddishpurple in fall. Drought-tolerant.Introduced by a New Jersey nurseryfrom a Long Island, NY source.

'Sunsplash '. A slow-growing formwith bright yellow and greenvariegation and orange fall color.

'Temple Jewel' . Subtly variegatedfoliage of green, gold, and light pink,

boldest on new growth; older foliagereverts to green with a light greenedge, variable expression, smallflowers and normal growth habit.Not as colorful as 'Goldstar'.

'Trinity Star' . Selected by an Oregonnursery. New growth is a mottled showof pink, green and white. Leaves areclustered in a twisted whirling pattern,which forms a flat-topped dense outline.Fall colors are pink and red.

'Triple Crown' . Plant with smalland dainty growth habit, heavyflowering with blooms mostly intriple clusters. Plant hardy to -20F.Source from Milton, MA.

'Variegata' . There is more than onevariegated form under this name incultivation. The cultivar originatedin Japan and was introduced to LongIsland, NY in 1862. Leaves can begreen but heavily streaked withwhite, yellow or gray-green;marginal or centrally variegated,sometimes all on the same plant.Variegated kousas are usually slowergrowing and often are unstable withbranches of the variegated leavesreverting to green, which must bepruned to maintain variegation.

'Weavers Weeping' . Exceptionallyheavy flower display on weepingbranches. Easy to train a dominantleader with remaining branchescascading toward the ground.

'Willamette' . 1995 Oregonintroduction. Holds dark greenfoliage color even in hot, drysummers. Excellent fall color, prolificflowering.

'Wilton' . 1978 New Jerseyintroduction. Plant holds flowerslonger than normal.

'Wolf Eyes' . Center of leaf is gray-green, with a bright white marginthat is scorch-resistant; leaf surfaceis somewhat rippled. Slow-growing,compact habit. White bracts haveless impact than on green-foliagedcultivars. One of the best and moststable variegated forms.

'Xanthocarpa' . Yellow fruits. Severalforms may pass under this name.

Many other cultivars have beenselected and named with variousattributes of growth habit, flowering,foliage variegation, and fruit sizeand color. Few of these are readilyavailable, but some may be obtainedfrom specialist nursery growers orfound in arboreta. New cultivarscontinue to be introduced, forexample 'Samaritan', 'ChristianPrince' and 'Galilean'. Some are toonew to be described. There appearsto be increasing interest in usingimproved C. kousa cultivars inAmerican gardens because of theirimproved drought and heat tolerance.

'Wolf Eyes'. Credit: Willard T. Witte


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Cultivars of Pacific Dogwood,Cornus nuttallii

Partly because of its smallerrange, there has been less activityin cultivar development in this spe-cies. Pacific dogwood is difficult togrow in the Eastern U.S., in partbecause the bracts do not completelycover the flower cluster during thewinter, leading to cold injury of theexposed flowers.

'Boyds Hardy' . Propagated fromthe sole survivor of a batch of seedlings grown in Tennessee thatwithstood 19 degrees below zero in1964. Rare.

'Colrigo Giant' . Blooms up to 8inches across with overlapping, cup-shaped bracts. Extra large, heavy-textured green leaves; wonderful fallcolor. Cultivar name formed bycombining the initial letters of theColumbia River Gorge, OR, where itwas found before 1963.

'Eddiei' . Leaves are green-streakedand spotted with gold. Discoveredgrowing wild about 1918 by H. M.Eddie.

'Goldspot' . Striking leaves, heavilysplotched with gold. Similar to'Eddiei'.

'North Star' . Strong, vigorousgrowth; dark purple, young shoots;and larger flowers than the species.Leaves have wavy margins. Rare.

'Pilgrim' . Southernmost specimentested by the Saratoga HorticulturalFoundation in California. Foundwild along highway Rt. 17 nearSanta Cruz County. Blooms up to 4inches across.

'Eddies White Wonder' . Hybrid of Pacific dogwood and floweringdogwood from controlled cross madeby a West Coast nursery. Combineslarger flowers of the former withexcellent autumn color of the latter.Branches becoming pendent with age.

Interspecific HybridDogwoods

Chief among these is theStellar series introduced byRutgers University in the early1990s, which resulted from crossesbetween kousa dogwood andflowering dogwood. Thesecultivars grow fast when young,and take several years to developa heavy floral display andspreading branching habit. Theyare distinctly upright growingwhen young. In flower form andblooming time they areintermediate between the parentspecies. Except for Ruth Ellen TM

they appear to be generally freefrom the major dogwood diseasesand insects. They are all sterileand set no fruit, and the energysaved appears to be spent inflower bud formation, as all areexceptionally floriferous. Theyhave been patented andtrademarked. We list thetrademark name.

There are also hybridsbetween Pacific dogwood andflowering dogwood (see 'EddiesWhite Wonder' above) andbetween kousa dogwood and C.capitata , Evergreen Himalayandogwood (see 'Norman Hadden'and 'Porlock' below).

Aurora TM . Vigorous andupright when young. Bracts arewhite and have a heavily textured,velvety appearance that becomes

creamy white as they age.Extremely floriferous.

Constellation TM . Vigorous and erectwhen young. More like C. kousathan C. florida in branching habit,but with more branches near theground. Mature height at 20 yearsestimated at 22 feet, with an 18-footspread. White egg-shaped bracts withacute tip do not overlap. Bloomseason starts about three days aftermost C. florida stop blooming andlasts about two weeks. Extremelyfloriferous. Wine red fall color,holding leaves late into the season.

Celestial TM (formerly Galaxy TM).Begins bloom 4-6 days after RuthEllen TM. At first, bracts form a deepcup and have a greenish tinge, butthey flatten out and become fullywhite in a few days. Bracts arerounded, well textured and slightlyoverlap.

Ruth Ellen TM . Mature plants widerthan tall, estimated at 19 feet inheight and 24 foot spread after 20years. White bracts become showy asflowering dogwood season ends.Bracts do not overlap and are roundto slightly egg-shaped with atapering base and a bristle tip.Susceptible to powdery mildew.

Stardust TM . Appears to have droppedout of nursery production sinceintroduction. Bracts do not overlap.

Stellar Pink TM . Vigorous and erectwhen young. Mature size and formsimilar to Constellation TM. Flowerheads are without a stalk. Rounded,overlapping soft pink bracts, withmore intense coloration in coolerweather. Bracts are egg-shaped witha short acute tip and tapered base.Bloom season begins about six daysafter C. florida ends.

'Norman Hadden' . Probably ahybrid of C. kousa and C. capitata ,Himalayan Evergreen dogwood, anOriental warm temperate tosubtropical species with blooms andfruits similar to C. kousa . A maturetree in southern England in 1989was about 12 feet tall and 16 feet

wide. Bracts open creamy white in June and age to a deep pink in July.Virtually unknown in the U.S.

Stellar Pink TM of the Stellar series. Ahybrid cross of Cornus florida andCornus kousa.Credit: Willard T. Witte


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'Porlock' . Same type of cross as'Norman Hadden'. The plants appearvery similar to C. kousa in foliagecharacteristics, but hardiness andblooming is unknown.

How to Grow theFlowering Dogwood

The flowering dogwood willgrow in a variety of exposuresand soils, but it does best in awell-drained soil that receivesregular rainfall throughout thegrowing season. Dogwoods willgrow in sun or shade, but innature, dogwoods are seldom

found growing in full sun. Thenatural environments for dogwoodare in partly shady places and theedge of woodlands. Flowers aremore abundant and typically treesare shorter and more compact insun than in shade. Plantingdogwoods in full sun withoutirrigation is a major contributorto stress that may cause plants todie after transplanting, or may bemore likely to be invaded bydogwood borers.

Thus, site selection is veryimportant. In choosing a site toplant flowering dogwood, it maybe wise to observe dogwoods intheir natural environment. Somenatural dogwoods die of drought,disease and pest attack along theway, but much can be learnedfrom observing natural sites.Consider the following:

In natural environments, fewdogwoods are found in fullsun or out by themselves.They are found at the edge of woodlands or mixed withother kinds of trees, usuallylarger than the dogwood.

All of natures trees start fromseed and grow in place, sothere are no transplantingproblems.

In nature, there are fewchances for injury to the treestrunk and roots. This is not

the case when dogwoods areplanted in managed land-scapes. Soil is piled aroundsome trees and taken awayfrom others. In other cases,soil is compacted over the rootsystem. The dogwood has ashallow, fibrous root systemand can be seriously affectedby fill soil. Digging or ditch-ing may cut some roots.Trunks are often de-barkedby lawnmowers and stringtrimmers.

Native dogwoods occur wherethey are in harmony with theenvironment. Borers attack

few natural understory dog-woods, for instance.

Although nature has win-ning ways, we can change some of them and still grow dogwoodsuccessfully in full sun, in thelawn and in the woods. Too manyof our transplanted dogwoods nowdie within the first few years. Bylearning more about dogwood,most of this loss can be prevented.

SoilThe kind of soil is not of

great importance in growing

flowering dogwood. The best soilwould be slightly acid with a fairamount of organic matter andwould not dry out quickly insummer, like a gravelly soil. Themost important factor is for thesoil to have good internal drainageso it is not saturated with waterduring wet weather. Dogwoodabsolutely will not tolerate satu-rated or poorly-drained soil, evenfor a few days.

When to Plant The best time to plant

dogwood is during the dormant

season, late fall through spring,when the ground is not frozenor so wet as to hamper digging

or to affect soil structure. Inwarmer climates, January canbe suitable, weather permitting.Dogwoods grown in field pro-duction and harvested with asoil ball, called balled andburlapped or B&B, are typicallyavailable from nurseries in latefall to early spring. It is best topurchase a B&B dogwood withina few months of harvest.

Container-grown dogwoodsare offered year around and canbe planted any time of the year,providing soil moisture isavailable.

Dogwoods are harvested in

the dormant season as bare-rootplants, but generally they aresold as liners to other growers.Seldom are dogwoods harvestedas bare-root plants sold in thelandscape market. If you shouldobtain bare-root plants, keep theroots moist and do not allowthem to dry out. Plant the treesas soon as possible. Dogwoods aretemperamental as bare-rootplants and survivability willincrease if planting is donequickly after being lifted fromthe nursery.

We do not recommendtransplanting trees from naturalareas because of the danger of spreading disease, namely

Discula anthracnose. Purchaseyour dogwoods from a reputablegarden center. Avoid trees withbroken or dead branches, trunkdamage or leaf spots. These aresigns of unhealthy plants.

How to Plant Dogwood naturally occurs

as an understory tree in areaswith high organic soil andplenty of natural mulch. They donot perform well in areas of poordrainage, or extremely dry sites.Even though dogwoods naturally

occur in partial shady areas,they can perform well in fullsun, provided adequate soil


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moisture is available. Dogwoodshave a shallow root system thatcan be adversely affected inperiods of drought. Good plant-ing sites and proper plantingprocedures will ensure thedogwood gets off to a goodhealthy start in the landscape.

The first rule for plantingany tree is to dig a hole largeenough to accommodate all theroots. A good practice is to digthe hole two to three timeswider than the ball of soil orspread of the roots. Dig thehole with sloped sides, ratherthan straight, to give the newfeeder roots maximum room togrow. Don't dig any deeper

than the root ball or container.Unless backfill soil is firmed

thoroughly, the plant willslowly settle and subsequentlybe too deep. Laying a shovelhandle or straight edge acrossthe hole helps to determine theproper depth (Figure 2). Al-ways avoid setting the dogwoodtree any deeper than it grewbefore transplanting. It ispreferable to set the tree acouple of inches higher thanthe soil level, especially if thesoil is a heavy clay.

Use the same soil thatcame out of the hole for back-fill. The assumption that soilamendments like peat mosswill be helpful to the plantsestablishment and survival has

not been proven in research.Adding soil amendments is

likely to create a pot whereroots grow in the amended soil,but do not penetrate and growwell into the native soil. Theonly time we would recommendamending the backfill is in agravelly soil where moistureretention is needed.

For balled and burlappedtrees, 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 youhave is to try to burn a smallpiece. Plastic burlap will meltbefore burning. Be sure to

completely remove any stringsfrom around the stem or trunkand fold the burlap away fromthe trunk. The string may besisal or polypropylene plasticand eventually will girdle thetrunk if left on.

Large B&B trees are oftendug with a mechanical spadeand placed in wire baskets linedwith burlap at the nursery. Thewire basket helps support theroot system while moving thetree. Always handle a large treeby the root ball, not the trunk.Large trees may require two ormore people to carry them, orthe use of a tree dolly. Do notremove the burlap and twinebefore the plant is set in theplanting hole. The tree shouldbe placed on solid ground ratherthan loose soil. Untie any rope,

jute or polypropylene twine thatis tied around the trunk. Pin-ning nails should also be re-moved from the upper part of the root ball. It is not necessaryto remove the wire basket, butcut off the top ring and fold theburlap down or cut off the topthird of burlap. Backfill thehole halfway with existing soil,tamp down lightly, water tofirm the soil and eliminate air

pockets. Finish backfilling andwater again. Rake the soil

Figure 2a. Measuring the planting depth of a B&B root-ball.

Figure 2b. Planting a B&B tree.Credit: UT Extension PB 1621, Planting Ornamental Plants by Donna C. Fare, 1999


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such as 10-10-10 or 13-13-13 andspread it over the ground underthe canopy and branches. Use upto 8 ounces (1 cup) per inch of trunk diameter. Water in well toprevent damage to grass. Foroptimal growth, apply fertilizer

just as buds start to swell in thespring, before leaves start to grow(February and March) and anapplication in May-June. If thistechnique is used, apply 1/2 cup (4ounces) at each application.

Too much nitrogen alongwith too much water mayencourage strong vegetativegrowth. This may not be at all

bad, especially when the tree isyoung. However, excessivevegetative growth may beresponsible for a poor set of flower buds. In such a case,using less nitrogen will probablyyield more flowers. It mayrequire one to three years for afast-growing tree to slow downenough to set a good crop of flower buds.

Mulching The forest floor is mulched

naturally with leaves. Thenutrients are recycled. In land-

scapes, newly planted and oldertrees will benefit from mulching.Mulch helps to hold soil moistureand can reduce or eliminatecompetition from weeds andgrass. If weeds start to grow inthe mulched area close to thetrunk, hand-weed that area. Donot use a lawnmower or stringtrimmer close to the tree trunk.

Mulch can be organicmaterial, such as compostedleaves, grass clippings, pineneedles, wood chips or shreddedbark. Avoid using any organicmaterial that is fresh or notcomposted. A layer 2-3 inchesdeep, extending out about 2-3feet from the trunk, is recom-mended. Don't overdo it. Mulch

evenly over the entire area sothe backfill is even with theexisting soil line. The top of theball or container surface shouldbe visible. Remove excess soil.Cover the entire area with 2-3inches of mulch. A thoroughsoaking with water finishes theplanting operation and is a goodsoil-firming technique.

Water container plantsprior to planting. Remove theplastic container. Check theoutside of the root ball and cutany circling or girdling roots. If the root system is matted on theoutside of the ball, use a sharp

knife to make three or fourshallow vertical cuts from top tobottom. This is a form of rootpruning and will help stimulatenew root growth. Do not beafraid to cut twisted roots.

A primary rule for plant-ing a dogwood tree is never letthe roots become dry. For treeswith a ball of soil, this isusually not a problem. Still,balls or containers that arestored for a while must not beallowed to dry out. For bare-root seedlings, keep rootscovered with a damp cloth,burlap or moist packing mate-rial such as moss, mulch orwood shavings. The fine rootsshould never be allowed to dryout. Healthy dogwood roots willhave white growing tips.

Care AfterTransplanting

After transplanting, treesmore than 8 feet high may needto be secured with stakes or guywires during the first year toprevent them from being blownabout or dislodged by high winds.This may not be necessary withlarge B&B plants due to the

weight of the root ball. Large-container dogwoods are grown ina media that is much lighter

than soil; thus staking may beessential. However, do not stakethe plants so tightly that theycan not move at all. A certainamount of movement or flexingtends to strengthen the trunk asnew growth occurs. Remove thestakes and guy wires at the endof the first growing season.

Lawnmowers and stringtrimmers injure many youngdogwood trees, and those injuriesattract dogwood borers. The bestway to keep the lawnmower orstring trimmer from injuring thetrunk is to maintain a weed-freeand grass-free mulched area

extending out 18-36 inches fromthe trunk.

Flowering dogwoods areespecially prone to borer attackduring the first two years afterplanting. Tree stress and trunkinjury invite borers. A sprayschedule, as discussed in theInsects section of this publica-tion, should be followed begin-ning early in the first growingseason to control this pest. Thespray schedule combined withkeeping the trunk free frominjury will minimize the risk of borer damage.

Fertilizing Little or no fertilizer is

recommended the first season.Research has shown that the treewill not respond much at all tofertilizer the first growing seasonafter transplanting. When thereis a desire to obtain fastergrowth, fertilizer can be appliedbeginning early in the secondseason. The tree may never needextra fertilizer if the soil ismoderately fertile and growthand foliage color are acceptable.A well-fertilized lawn will benefittrees planted in the lawn.

The best fertilizationpractice for dogwood trees is touse a complete garden fertilizer


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more than 4 inches deep or piledup against the trunk can bedetrimental. Excessive mulch canimpede water and air movementto the root system, and if mulchkeeps the trunk bark continuallymoist, it could cause decay.Additional mulch should beadded every couple of years toreplace that which slowly decays.

Watering For most soils and most

years, natural rainfall is usuallyadequate to support good growthof dogwood. But during the firsttwo growing seasons followingplanting, dogwoods often requireextra water to eliminate stressand promote new growth. How-ever, be sure to water trees, evenmature trees, during severedrought periods at the first signof leaves wilting. Dogwoods areshallow-rooted and cannot drawon moisture reserves deep in thesoil. Drought-stressed dogwoodtrees are apt to wilt or dropleaves and lose part or theirentire berry crop if they do notreceive supplemental watering.The most severe drought stressusually occurs in late summer.

Avoid overwatering newlyplanted dogwoods. Seldom is itnecessary or desirable to wateryoung trees more often than oncea week. One good soaking weekly(about 1 inch of water) or evenevery other week would be farbetter than a small amount of water daily. Water applied insmall amounts seldom providesadequate moisture throughout theroot system and encourages rootgrowth near the soil surface. Rootsneed air to live just as much asthey need water. Overwateringdrives the air out of the soil andwill likely result in root decay.The symptoms (wilting and leaf scorch) of a tree dying from rootrot caused by too much water are

the same as those of a tree suffer-ing from a lack of water.

Caution . Transporting plantsin leaf can cause severe injury.Avoid windburn or desiccation bycovering the plants with a tarp orcover during transport. Do not letcovered plants sit in full sun.Damaging temperatures build upquickly. Lift plants by the rootball, not the trunk, to prevent rootbreakage in the soil ball. Theplanting techniques describedabove should start your dogwoodsoff to a long and healthy life.

Pruning Once a dogwood is plantedand established, it needs little orno pruning. Remove dead, dis-eased or broken branches as soonas they become apparent. Re-move any suckers that appear atthe base of the trunk, especiallyon grafted trees. Otherwise,pruning is a matter of personalpreference. Some people prefersome limbs to branch out low tothe ground. Others may prefer toremove low limbs or trim backlimbs near a walkway or againsta house. Multiple trunks may beeither eliminated or retained. In

any case, make pruning cutsclean and nearly flush with theremaining branch. Leave only ashoulder. Never leave a branchstub. Pay attention to borerprevention practices, becausepruning wounds are attractiveto borers and serve as entrancesites. Late winter to earlyspring is the best time forpruning. Pruning may be doneany time it is needed, but mostpractitioners prefer the dormantseason. Rapid spring growthwill begin the healing processfaster than at any other time.Even pruning during bloom isnot damaging to the tree andcan sometimes yield some nicebranches for decoration indoors.

Will My Dogwood Bloom?

The question, Will mydogwood bloom? is asked manytimes upon purchasing a tree.Homeowners can be assured theanswer to that question is nearlyalways Yes. Probably allhealthy dogwoods will bloom.Most unhealthy ones will, too. Infact, a tree fatally injured byborers or lawnmower damagewill bloom heavier than normal,although perhaps with smallerflowers. Such an injured tree willoften die during the summerfollowing the extra heavy bloom.

Not all dogwoods beginblooming at the same age.Nursery-grown plants of somecultivars have flowers the secondor third year, while native treesmay be 4-6 years old or olderbefore blooming. One can tell bySeptember if a tree will bloomthe next spring. The button-shaped flower buds are formedthe summer before blooming. If they are not present on the treeby September, the tree will notflower in spring. If the largebuds that tip the branches can befound, the tree should bloom.There is very little danger of cold

weather killing the flower budsexcept on the extreme northernedge of the dogwood range.

Dogwoods do not alwaysbloom the same amount eachyear. In fact, if a healthy dog-wood tree blooms heavily oneyear, followed by a large berrycrop, then the tree will likelybloom poorly the following year.The simple reason is a largeamount of energy is required toproduce a large number of flowers and fruit. Too littleenergy then will be available forthe tree to produce a large num-ber of blooms the following year.

This is why a good dogwoodshow one year is often followedby a poor show the next. Very


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likely the year following a poorshow will be good again.

Certain individual dogwoodtrees have the habit of cominginto partial bloom in the fall, atleast in some years. One cultivar,'September Dog', was evenselected and named because itconsistently showed this oddbehavior. Such trees are usuallyfrom a southern selection and theflower buds may have a differentdormancy pattern than others.Some flowers may develop whensummer and fall stress periodsare followed first by moderatelycool nights and then an unsea-

sonably warm period in the earlyfall. These flowers are almostalways on abnormally longflower stalks with smaller thannormal bracts that are oftencontorted and may be blushedwith pink. If berries do form,they are lost to frost, so fallblooming is no advantage to theplant. Fall dogwood blossoms arean interesting abnormality thatdoes not appear to hurt the tree.

IntegratedManagement of Insects and Diseasesof Flowering Dogwood

Dogwoods can be killed orseriously damaged by insect anddisease pests. Poor culturalpractices can often cause a declinein the physical condition of thetree favorable for infestation byinsects and diseases. Periods of hot, dry weather, trees growing infull-sun location and accidentalinjuries with garden tools fre-quently provide the openingthrough which these pests enterthe plant tissues.

Specific pesticide informationis not given in this publication.Pesticide registrations, labeling

and use are constantly changing.Consult with your local Extensionagency for the currently recom-mended chemical controls.

Insects

The Dogwood BorerThe dogwood borer,

Synanthedon scitula (Harris), isthe most destructive insect pestof the dogwood. Damage is doneunder the bark on the trunk andat the base of older branches bya cream-colored larva with areddish-brown head. The larvahas two reddish-brown spotsdirectly behind the head on thethorax. The full-grown larva isabout 0.6 inch long. The adultdogwood borer is a blue-blackmoth with clear wings and someyellow markings. The adult mothdoes not damage the tree.

These moths emerge over afour-month period from springthrough September, beginning inMarch in the extreme South, inlate April in eastern Tennessee,in mid-May in Virginia and latein May in Connecticut. The

female moth lives only seven tonine days; during this time shelays the eggs that produce thedestructive larvae. New mothscontinue to emerge, mate and layeggs over an extended period of time from infested trees. A larvahatched during one year will notmake an adult until the followingyear. The larva does its damagewhile tunneling and developinginside the tree from one year tothe next. After this feedingperiod, the larva forms the pupa,and in eight to 12 days the adultemerges from the pupa case.

Damage Eggs laid on thedogwood trunk by the moth hatchinto very small larvae in eight to10 days. Some of the young

Dogwood borer adult moth.

Credit: Frank A. Hale

Dogwood borer larvae damage.Credit: Mark T. Wilson


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Asian ambrosia beetle frass from the trunk of a crape myrtle.Credit: William G. Hudson

Asian ambrosia beetle in ambrosial fungifilled brood gallery.Credit: Frank A. Hale

larvae find an opening in thebark in which they can enter.Once inside, they are well pro-tected and begin feeding, butprobably will not kill the dogwoodunless the tree is very small.Usually it takes several larvae inone tree to completely kill thetree. The tree will die wheneverone or more larvae eat completelyaround the trunk and block theflow of food from the treetop tothe roots. Often the tree will dieback to the point of injury, andnew shoots will arise below thispoint. These new shoots can oftenbe kept to regrow a new tree

providing additional borer injurydoes not take place.

Fortunately, the dogwoodborer will not attack all dog-wood trees. The adult moth is alight-loving insect. Nativetrees in their natural understoryhabitat are seldom attacked.Trees that are never damagedby sunscald, lawn mowers,construction equipment or strongwinds are much less likely to beattacked by borers than treesthat are first stressed andinjured in some way.

Control Damage fromthe dogwood borer can be pre-vented by protecting the tree

trunk from the larva and byremoving the larva after it is inthe trunk. Obviously the firstmethod is best. Prevention maytake place in one or more of thefollowing ways:

Make pruning cuts in latewinter to facilitate rapidhealing during rapid springdiameter growth.

Avoid physical injury to thetree by unnecessary cuttingor bruising. Mulch aroundtrees or remove grass byhand rather than mowingclose to a tree.

Insecticides can be used onthe lower branches and trunkto kill newly hatched larvaebefore they can enter the tree.Once inside the bark, thelarvae may not be killed byinsecticides. For maximumprotection, an insecticideresidue should be on thetrunk during the entire egg-laying period. Spray thetrunk, the lower limb scaffoldand the soil around the barkof the trunk. These preventa-tive insecticide sprays willalso aid in the control of flatheaded borers.

Asian Ambrosia BeetleThe Asian ambrosia beetle,

Xylosandrus crassiusculus(Motchulsky), is able to attackapparently healthy trees, shrubsand vines of a wide host range.The reddish-brown femalebeetles are 2.1 - 2.9 mm long,while the males are only 1.5mm long. The larvae are white,legless, C-shaped and noteasily distinguishable from thelarvae of other ambrosia beetles,bark beetles and most weevils.The larvae feed on the ambrosialfungi that the adults introduceinto the galleries. The wilting anddeath that occur in many of theattacked plants is not thought to

be caused by gallery formation orthe ambrosial fungi. The Asianambrosia beetle is thought to be avector of wilt fungi.

Signs of attack includetoothpick-diameter tubes of sawdust-like frass (excrement)sticking out from the many smallholes in the trunk or infestedlimbs, wilting and oozing sap. Theflight of the adult female beetles,determined by trap catches,occurs in late winter to earlyspring during warm spells whilethe trees are still dormant. If trees are being attacked, recom-mended insecticide sprays shouldbe initiated at 10-14 day intervals

and discontinued only after theplants have leafed out.

PrecautionaryStatement

To protect people and theenvironment, pesticides should beused safely. This is everyonesresponsibility, especially the user.Read and follow label directionscarefully before you buy, mix, apply,store or dispose of a pesticide.According to laws regulatingpesticides, they must be used onlyas directed by the label. Persons whodo not obey the law will be subjectto penalties.


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Dogwood Club GallThe dogwood club gall is

recognized as a distinct swellingnear the tip of branches. It maybe found on transplanted treesand those growing in the natu-ral state. The gall is caused by asmall (2 mm long), reddish-brown fly, Resseliella clavula(Beutenmueller).

In the spring the female flylays eggs in the small terminalleaves. The resulting tiny larvaebore into the twig at the base of aleaf. One month after eggs arelaid, swelling is noticeable. Thelarva completes its growth inside

the gall by September, exits anddrops to the ground to overwinter.The adult flies will emerge thenext spring to repeat the cycle.

Damage A light infesta-tion of club galls will hardly benoticed and will not stunt treegrowth. Most buds that developbeyond the gall will die. Treeswith many galls will not beattractive and the number of flowers the following spring willbe reduced.

Control The club gall canbe controlled by pruning andinsecticides. By pruning out twigscontaining galls before August 1and burning them, future infesta-tions can be reduced.

Dogwood Twig BorerThe dogwood twig borer,

Oberea tripunctata (Swerderus),causes wilted leaves or thedropping of girdled branches.Damage is done by a darkgreen, long-horned beetle thatmeasures about one-half inchlong and has three black spotson the light tan prothorax(directly behind the head). Thebeetle is usually found only insmall numbers.

Adult beetles begin toappear in April and May in

North Georgia, from Maythrough July in Pennsylvaniaand from late May to earlyAugust in Michigan. They feedon the midvein on the undersideof the leaf that can cause the leaf to curl downward. This leaf feeding causes little damage. Themore serious damage is associ-ated with egg laying and theresulting larva. The female adultbeetle uses its mouthparts tomake small punctures around thebranch to girdle it. Two girdlesare made 1/2 to 1 inch apartabout 3-6 inches from the tip of asmall branch. The beetle then

lays an egg between the twoseparate girdles. The egg hatchesin seven to 10 days and theyoung larva tunnels into thebark. The developing larvatunnels down the center of thelimb, expelling frass through arow of small holes in the bark. Aportion of the branch may be cutoff from within. The larva passesthe winter in the center of thestem. The borer pupates betweentwo plugs of sawdust. The devel-opment from egg to adult usuallytakes two years.

Damage The wilting of leaves and the drooping girdledtwigs are the main evidence of damage. Since the beetle occursin small numbers, trees are notlikely to be killed, but appear-ance may be impaired.

Control Prune infestedlimbs in the spring before theadult beetles emerge from infestedtwigs. Make pruning cuts belowthe tunneled part of the branchand burn prunings. This pruningcut will often be 6 inches or sobelow the girdled area.

Dogwood SawflyThe dogwood sawfly,

Macremphytus tarsatus (Say), is adefoliating pest primarily of gray

Dogwood club gall at tip of twig. Credit:Frank A. Hale

Wood fibers pushed out of hole in the twigby dogwood twig borer. Credit: Frank A.Hale

Dogwood twig borer larva in hollowed outdogwood twig. Note plug of coarse woodyfibers at end of twig. Credit: Frank A. Hale

dogwood in the Great Lakesstates and the Northeast. Saw-flies are classified in the sameinsect Order, Hymenoptera, asants, bees, wasps, yellowjackets,hornets and horntails. Whilethey do not sting, the adultfemale sawflies use their serratedovipositor to insert eggs into theleaf tissue. The adults emergefrom late May through July (onegeneration per year) and soondeposit more than 100 eggs inthe underside of a single leaf.


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The larvae of foliar feedingsawflies have more than five pairof fleshy prolegs on the abdomen,while butterfly, moth and skippercaterpillars (Lepidoptera) have amaximum of five pair.

Damage After hatching,the yellowish orange larvaeskeletonize the leaf. They soonmolt to the second instar stageand become covered with awhite, powdery material thatcan be rubbed off. They thendevour all of the leaf except forthe midvein. The last instarlarvae are 1 inch long with four

rows of black spots in additionto the white material. Thelarvae leave the plant in searchof a place to overwinter, wherethey bore into rotting wood andcan even damage wooden clap-board, wood-fiber wallboard orgarden furniture.

Control Spray the foliagewith recommended labeledinsecticide when dogwood saw-flies are first detected.

Rose LeafhopperDogwood leaves become

white and stippled due to thefeeding activity of the roseleafhopper, Edwardsiana rosae(Linnaeus). Leafhoppers over-winter as eggs in the stems of roses, blackberry or raspberry.Eggs usually hatch in the springafter the threat of frost haspassed. The young, greenish-white, red-eyed nymphs feed onthe underside of the leaves untilthey mature.

The first brood of adultsmigrates to dogwood, maple, elm,apple and other woody plants.They insert eggs into the planttissue on the underside of theleaves. The eggs soon hatch andthe summer generation continuesto develop. Several generationswill develop during the season.

Control Spray the foliagewith recommended labeledinsecticides when leafhoppersappear. Repeat applications at 7-10 day intervals as needed.

Cottony Maple ScaleThe cottony maple scale,

Pulvinaria innumerablilis(Rathvon), is a very large andconspicuous scale insect found on awide variety of ornamental plants.Adult females are generallyreddish-brown and have a medianridge. Adult females overwinterand enlarge rapidly in the earlyspring. The white ovisacs contain-

ing up to 1,000 eggs are developedunder the raised abdomen in midto late spring. The crawlers moveto the leaves in late spring, wherethey develop into adults in latesummer. This scale produces largequantities of honeydew, whichfrequently supports the growth of sooty mold.

Control Lady beetles andother predators and parasitoidswill often control this pestwithout the need for insecticide if given time. Dormant oil can beapplied in late winter while thetrees are still dormant. Targetthe crawlers (first active imma-ture stage) with a recommendedlabeled insecticide in the spring.A couple of applications atweekly intervals may be needed.

Walnut ScaleThe walnut scale,

Quadraspidiotus juglansregiae(Comstock), can also cause

extensive damage to dogwood byinhibiting the terminal growthof limbs and by encrusting thelimbs and trunk leading todeath of the tree. Initial infesta-tions occur on the underside of the limbs, but will completelyencrust the limbs within two tothree years. The walnut scale

Walnut scale on a dogwood limb. Credit: Frank A. Hale


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has two generations per year.The adult female walnut scalelays eggs in June and again inAugust in Ohio, in mid-May andagain in mid-August in Califor-nia. The crawlers emerge fromthe eggs several weeks afterthey are laid.

Control Adults aredifficult to control because of the wax-like protective coveringover their bodies. Crawlers arethe easiest stage of the walnutscale to control. Consult withyour local county Extensionagent for when to expect crawl-

ers and apply the recommendedchemical controls.

Two-spotted Spider MitesTwo-spotted spider mites,

Tetranychus urticae Koch, arewarm-season mites that canquickly build to tremendousnumbers in hot, dry weather.They can develop from egg toadult in only eight days at 77-95degrees F. They attack more than180 host plants, including 100cultivated species. Two-spottedspider mite populations oftenincrease on common plants suchas violet, chickweed, pokeweed,wild mustard and blackberry.They can then disperse to otherplants, including dogwood.

Damage Two-spottedspider mites damage leaves bypiercing the outer leaf surfacewith their sharp, slender mouth-parts. When they extract the sap,a tiny bit of leaf tissue collapsesin the area of the puncture.Soon, a minute chlorotic (yellow)spot forms at each feeding site.After a heavy attack, an entireplant may become yellowed,bronzed, partially defoliated orcompletely killed. Two-spottedspider mites are generally foundon the underside of the leaveswhere they feed, lay eggs and

spin webbing. High populationsof two-spotted spider mites,especially during extended dryperiods, can entirely cover leaveswith webbing.

Monitoring Inspectdogwoods periodically during thespring and summer. Use amagnifying glass to look for themites, cast skins, eggs and theirwebbing on the underside of leaves. Hold a white card underthe plant foliage and shake ortap the foliage to dislodge mitesonto the card. The mites can beobserved as they crawl across the

card. Observe the top of leavesfor the tiny, chlorotic feedingspots on either side of the mid-vein of the leaf.

Control It is best tobegin chemical treatments at thefirst signs of mites or mitedamage. At least two sprays, fivedays apart, will be needed.Summer horticultural oil spraysshould not be made more thanonce per week. Some miticideshave a long residual so that oneapplication is sometimes suffi-cient for control of small popula-tions. To slow the buildup of resistance to some of the newermiticides, the label may limit itsuse to once per year, or not allowit to be used in successive appli-cations. Some miticides onlycontrol immature mite stages, soa different miticide to controladult mites may be required.

In the landscape, dogwoodsare planted into all types of situations. While the inner foliageof the trees may be shaded, treesmay be planted in direct sunlightor into full or partial shade. Treesmay be located in open (airy)areas or in landscapes thatcontain dense foliage. Dogwoods

may be planted in well-drainedsoils that are high in organicmatter. Weed control practices cancause either mechanical injuriesfrom cultivation or chemical(herbicide) injury. All of thesefactors may contribute to thestress of the tree and affect thetrees ability to resist plant pestsand pathogens.

To aid in identification of dogwood health problems, asimple key of common symptoms

Two-spotted spider mite webbed in a masson the tip of a peach leaf.Credit: Frank A. Hale


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Symptoms of spot anthracnose includereddish-brown, elliptical spots on (a) bractsand (b) leaves. Infected bracts may besmaller, distorted or destroyed.Credit: Mark T. Windham (both photos)

a.

b.

and signs of dogwood diseases isincluded (see sidebar). Commondiseases and an overall pestmanagement strategy are de-scribed below.

Documents

Dogwoods for American Gardens (PB1670)