The Minnesota

Shade Tree

Advisory

Committee’s

mission is to

advance

Minnesota’s

commitment to the

health, care and

future of all

community forests.

In This Issue2 President’s

Corner

6 Oak Wilt

7 Mulching

9 Pruning atPlanting Time

11 News Releases

12 CommunityProjects

14 STAC News

15 Tree Potpourri(Events andOpportunities)

16 Color In theLandscape

ADVOCATE • SPRING ’99

hether the reason for planting a new tree is torecover from losses courtesy of 1998’s stormseason, oak wilt, construction damage or sim-

ply the desire to plant a tree, tree health only beginswith best planting practices (Johnson, Ash, 1998) anda high-quality tree. Trees, likechildren, require a lifetime ofcare—sometimes intensivemaintenance as with urbantrees, sometimes just occa-sional guidance and attention.But no matter what the siteand the tree may be like, thefirst several years—the for-mative years—are the most important for developing worthyand healthy trees for our urban forests. Consider these myths:

■ “It made it through the guarantee period, soit should be just fine.”

Just about anyone can get a tree to survive for a growingseason or a year, so don’t be lulled into a false sense of securityand complacency once the tree has survived the normal, one-year guarantee that most retailers provide. Establishing healthytrees is a 15-20 year commitment beyond that survival guaran-tee period. All transplanted trees must first live through a per-iod of transplant shock, whether they’ve been dug and trans-planted from a field nursery or transplanted from a container tothe landscape.

■ “Trees seem to survive just fine inforests…why should I meddle with nature?”

Under normal circumstances, the transplant shock period isapproximately one year for each inch of stem caliper. Therefore,a three-inch caliper tree will need at least three years in the

W

Spring ’99

VOL. 2, NO. 2 • SPRING 1999

1Visit us on the Web at http://willow.ncfes.umn.edu/mnstac/mnstac.htm

Establishing New Trees continued on p. 2

GARY

JOHN

SON

With the extensivelosses of trees in manyMinnesota communitiesover the past year,spring planting andArbor Day activitiesmay take on new impor-tance in many parts ofthe state this season.With a focus on plant-ing, this Advocate canbe a handy guide toexperienced treeplanters as well asnovices as we worktogether to create andrebuild our communityforests.

Best planting practicesbegin with digging an

ample hole (above), contrasted here with theold way . . . the smallest

possible hole (left).■ ■ ■

Establishing New TreesBy Gary Johnson

2

President’s ornerCTree Buds

MnSTAC is completing its25th year of “speaking for thetrees.” Since inception our goalhas been to be a statewide organi-zation. Distance has kept us fromhaving many members outside theTwin City Metro area. This news-letter helps to bridge the distancewith information.

Our structure calls for re-gional STACs. As of today, wehave three:

■ HA STAC—Headwaters Agassiz

■ WC STAC—West Central

■ SE STAC—Southeast.

A fourth is in the formativestage in northeastern Minnesota.These groups help sponsor TreeCity Award events, tours andworkshops. The Northwest UrbanForestry Workshop at Crookston,now in its 15th year, is an example.

Opportunities abound!! You can:

✓ be part of one of these regionalcommittees

✓ help form one in your region ifnone exists

✓ recruit neighbors and col-leagues and serve on or form a“tree board” in your community

✓ serve on a MnSTAC committeein your area of interest.

Involvement may mean tak-ing a chance. You will, however,gain more than you give—regard-less of which level you serve. Youwill be “speaking for the trees.”You will also be living the formulaof 10 two-letter words:

“If it is to be, it is up to me.”

—Glen Shirley

MnSTAC’s President Shirley lives in a“rurban” area (southern DakotaCounty). He is Bloomington’s CityForester and an ISA CertifiedArborist.

landscape to recover from the shock of rootloss if it had been field grown, or culturalshock if it had been nurtured in a container bythe nursery. However, if the planting site is aparticularly harsh site, which is typical formany urban planting sites, this shock periodmay continue much longer.

The transplant shock period should beconsidered as the period of intensive care.Maintenance practices should focus on elimi-nating or reducing all unnecessary stressessuch as water stress (too much, too little),competition for root space from other plants(especially turfgrass), insect pests orpathogens that wound or defoliate the tree,nutrient deficiencies and unnecessary wound-ing. During this period, the tree’s energyshould be focused on root growth and estab-lishing a more characteristic root:shoot bal-ance for that particular species.

■ “I water my lawn with one inchof water a week, so I’m sure thatthe trees are getting plenty ofwater, too.”

Water is the single most importantrequirement for establishing healthy trees.And it’s not just water, but the properamounts and frequency of irrigation. Thereis no magical formula for correctly and ade-quately watering all types and sizes of trees—that “one inch of water per week” rule fortrees has no research to defend it. There isresearch that supports the practice of fre-quent—twice per week—irrigation, supplyingthree to five gallons of water directly to thesoil/root ball of the planted tree (two- to three-inch caliper trees; Gillman et al., 1998). Buteven this research-based information shouldbe used with caution and not accepted blindlyas the “rule” for watering all trees.

Trees require a uniformly moist soil to adepth of at least eight to ten inches. In a goodyear, with regular and adequate rainfall cou-pled with a layer of mulch over the tree’s rootsystem, irrigation may never be necessarybeyond the establishment period. But moreoften than not, rainfall is unpredictable. Inaddition, soil texture, structure and percola-tion (drainage of water) influence the amountof water available to a tree, and therefore maycause an adjustment to all “rules” about thefrequency and amount of irrigation supplied.For instance, sandy soils that drain rapidly

Site stress can lead to steminjury during the winter, partic-ularly in species used to themoist and shady forest such asthis white ash.■ ■ ■

GARY

JOHN

SON

Establishing New Trees, from p. 1

3

don’t retain water very long. Trees growing onthese types of soils will probably need irriga-tion more frequently than twice a week, espe-cially for larger trees planted in full sun inwindy and hot climates.

Conversely, trees planted in clayey soilsthat do not percolate adequately may requireless frequent irrigation. In fact, frequent irri-gations may do more harm than good by dis-placing essential soil oxygen, which in turnmay result in the death of the trees. So, prop-er water management is a matter of monitor-ing the tree’s health (watching for abnormalwilt), ensuring that the soil drains water ade-quately (a 24-inch column of water shoulddrain in 24 hours) and periodically checkingthe soil to a depth of eight to ten inches (use asoil probe).

■ “If a two- to four-inch layer ofmulch is good, then 20 inchesmust be tremendous!”

This may not exactly be a verbalizedmyth, but many people certainly act as thoughthey believe it! Adding two to four inches ofmulch—preferably an organic mulch—over theroot system of a new tree is one of the bestcultural practices employed. It’s a beautifulmimic of a typical forest floor. The mulchretains soil moisture and keeps it more uni-form (less drying out of the soil betweenrains), keeps the soil temperature more uni-form, all but eliminates competition for mois-ture from turfgrass, builds up a new soil layeras the mulch decomposes, and keeps lawn-mowers and string trimmers away from treestems. And, it is well documented thatmulched trees grow faster and healthier thannon-mulched trees on similar sites (Green andWatson, 1989).

More, however, is not always better—atleast when it’s piled up against the stems oftrees. Mulches, especially organic mulches,should never be piled up against the stems ofyoung trees. Organic mulches are more likelyto remain moist and this creates an environ-ment favorable to fungal pathogens. Treesthat have been wounded on the stem may bemore predisposed to stem canker pathogens ifthe mulch has covered the wound. In addition,trees that are more prone to form adventitiousroots (roots emerging from the stem) will formthese roots with ease if mulch covers the stem.Quite often, these adventitious roots developinto stem girdling roots. (For more informa-tion on the problems of excessive mulching,

see Rich Hauer’s article on page 9 of thisissue.)

Renewing mulch layers annually or peri-odically should be done with as much care asthe first layer. One to two inches of new mulchis usually sufficient, but don’t pile this on thestem. If mulch volcanoes are observed in thelandscape (inverted cones of mulch, creepingup the stems of trees), pull them down andaway from the stems and spread them out. Asa tree becomes larger, expand that originalthree- to five-foot diameter of mulch installedat planting to a 10-12 foot diameter ring ofmulch around the more mature trees.

■ “Wrapping the stems of treeswith paper or plastic will preventwinter injury.”

Unfortunately, there is still a lot of contro-versy surrounding the use of tree wrap forwinter protection. No harm will come from itif it’s done correctly—by placing light-col-ored wrapping on thestems in late autumnand removing it inearly spring—but thecold-damage benefitsare debatable. If thewinter injury thatneeds to be preventedrelates to rodent orother critter damage,however, installing aplastic or PVC sleevearound the stem andplacing another screenbarrier outside of theplastic can be effective(Johnson and Ash, 1998).

Two factors directly or indirectly affectthe incidence of stem damage to trees duringthe winter months: wounds on the stem andthe water status of the tree when it goesinto dormancy. Trees with stem wounds aremore likely to suffer wood or bark splitting,usually originating at one or more of thosewounds. And trees that are water-stressedgoing into dormancy are more likely to sufferwood or bark splits and frost cankers of thebark. So, limit the wounding—especiallyunnecessary large pruning wounds or mechan-ical injuries—and make sure the trees are notwater-stressed going into the winter. Winterinjury to stems will be greatly reduced.

While the role of treewrap in winter protectionis debatable, it’s certainthat rodent damage can bereduced with proper use ofscreen and plastic barriersaround the trunk.■ ■ ■

Establishing New Trees continued on p. 4

GARY

JOHN

SON

SPRING ’99 • ADVOCATE4

■ “It’s spring and the local gar-den center has a sale on fertilizer,so it must be time to fertilize mytrees.”

And the complementary statement:

■ “If two pounds of fertilizerare good for the tree, five to tenpounds must be tremendous!”

It is not common that trees suffer fromsoil nutrient deficiencies. More often, thecause of the suffering is from inadequatewater, poor/damaged root systems or anoutrageously high soil pH. And it may notbe an indication of poor health if a tree isnot growing very fast or is not getting verylarge. It may be perfectly healthy for thesite it’s growing in. If the average twig

growth rate is between two and sixinches, the color of the leaves appearsnormal for the species and the tree isnot suffering any abnormal die back,then it’s probably not in need of nutri-ents.

However, if the newly-plantedtree is in a very poor soil, or if thereis a need for more rapid growth (toquickly block a view, for instance),then fertilization can be beneficial.For most trees, fertilizer should beapplied in the spring or mid-autumn (after the trees have begun

their descent into dormancy). Ifnewly-planted trees are not likely to

ever receive very much attention afterplanting and the planting site soil is defi-cient, a slow-release, balanced analysis fer-tilizer mixed into the planting backfill soilat a moderate rate (four pounds of nitro-gen/1000 square feet) may be beneficial.

In other situations a “maintenance fer-tilization schedule” may be employed.Every four to five years, apply approxi-mately four pounds of nitrogen per 1000square feet of rooting area (Harris, Clarkand Metheny, 1999). This stimulates newgrowth but not excessively, especially if theproduct is in a slow-release form (releaseover a period of 3-12 months). Avoid addingfertilizer to the root system, however, if thetree is not receiving adequate water. Water

is still the overriding amendment thatdetermines plant health, even for estab-lished, mature trees.

■ “Remove one-third of thetree’s canopy when it’s plantedand there should be very littlepruning needed thereafter.”

A two-fold misconception! There’s noresearch that supports removing one-thirdof the canopy at planting. In fact, researchhas long shown that this type and extent ofpruning may be harmful, not only for treeestablishment but for long term form andstructure (Whitcomb, 1987). Anyone whocarefully examines the structure of mosturban trees realizes that they form newbranches and leaders, many of which arepoorly attached and/or placed. See RichHauer’s article on page 7 of this issue formore information.

At planting time, you should removeall codominant leaders, broken and deadbranches, branches that have included barkin their attachments and wounded or rub-bing branches. Revisit the trees at leastonce during the four or five years afterplanting to remove dead branches, watersprouts, suckers and other poorly attachedbranches or new leaders. At this time, itmay be difficult to visualize the exact formof the tree when it matures, but pruningshould encourage a well-balanced scaffoldbranching pattern, solid branch attach-ments and a single leader. (Scaffold branch-es are the main branches.) For moredetailed information on pruning, see thearticle Winter Pruning by Katie Himanga,Shade Tree Advocate, Vol. 1, No. 1, pages 5-7.

Ideally, all trees would be inspectedannually and cared for immediately.Suckers and watersprouts should beremoved in late summer. If you removethem in the spring, they are soon replacedby others that will need to be removed thatyear. Winter is the best time for structuralpruning—that is, establishing and main-taining that optimal scaffold system for thetree. Summer is a good time to check thetree for dying branches or others that rubagainst structures, people on sidewalks,trucks on arterial streets or power lineswhen the weight of full foliage bends thecanopy.

Establishing New Trees, from p. 3

ADVOCATE • SPRING ’99 5

Annual or seasonal care is notalways practical or possible in most com-munity landscapes. A goal of pruning alltrees every four to five years is attain-able, however. Although it is not optimal,it is usually adequate for most trees inthe establishment phase. Four to fivecycles of a four-to five-year pruning cycleshould prepare the trees for long termstructural integrity. Although mainte-nance pruning will continue for the life ofan urban tree, a well-structured treeshould require a minimal amount of livewood pruning as it matures. (For moreinformation on mature tree trimming,see the article Mature Tree CrownThinning by Jeff Rick, Shade TreeAdvocate, Vol. 1, No. 1, page 8.)

Many other important maintenancerequirements will likely emerge over theestablishment years of a tree—diseaseand pest control, storm repair, woundrepair—but these five factors (good plant-ing practices, watering, mulching, pre-venting injury, proper pruning) arearguably the most influential. All are rel-atively simple and much more cost-effec-tive than repair work, therapy andreplacement after the tree has becomelarger and unhealthy. And fifteen totwenty years go by too fast.

Gary Johnson is an Associate Professor ofUrban and Community Forestry at theUniversity of Minnesota, Department of ForestResources.

CitationsGillman, E.F., Black, R.J. and Bijan Dehgan,1998. Irrigation volume and frequency andtree size affect establishment rate. Journal ofArboriculture 24(1):1-9.

Green, T.L and G. W. Watson, 1989. Effects ofturfgrass and mulch on the establishment andgrowth of bare-root sugar maples. Journal ofArboriculture 15(11):268-272.

Harris, R.W., Clark, J.R., and Nelda Matheny,1999. Arboriculture. Integrated Managementof Landscape Trees, Shrubs, and Vines. 3rdedition. Prentice Hall. Upper Saddle River,New Jersey. 687 p.

Johnson, Gary and Cindy Ash, 1998. TheRight Way to Plant a Tree. Minnesota ShadeTree Advocate Vol. 1, No. 2, pages 5-7.

Whitcomb, Carl E., 1987. Establishment andMaintenance of Landscape Plants. LacebarkPublications. Stillwater, OK. 618 p.

Programmed Tree EstablishmentSeasons of Care: Years 1-20

Spring• Fertilize every 4-5 years (or in autumn) if

desired.

• Mulch every 2-4 years (or in autumn).

• Begin irrigation if rainfall is not adequate tokeep the soil moist to 8-10” depth.

• Remove winter stem protection in late winterto early spring.

Summer• Monitor health (diseases, pests, disorders) at

least once a year.

• Summer-prune for elevation and structure ifnecessary. Repeat at least once every 4-5years.

• Remove suckers and watersprouts in latesummer.

• Continue monitoring soil moisture and irri-gate to maintain adequate level.

Fall• Fertilize in mid-autumn (if not done in

spring) every 4-5 years if desired.

• Mulch every 2-4 years (or in spring).

• Continue irrigation if droughty, but reducefrequency to allow for normal onset of dor-mancy.

• Apply winter stem protection in mid-lateautumn.

Winter• Monitor structure of trees.

• Structurally prune trees during winter dor-mancy. Repeat at least once every 4-5 years.

• Remove winter stem protection in late winterto early spring.

SPRING ’99 • ADVOCATE6

Oak Wilt inMinnesota: It’s StillHere and We’re DoingSomething About It!By Jennifer Juzwik and Gary Johnson

es, oak wilt is still around and killing largenumbers of oaks annually in Minnesota.Although the progress of oak wilt has been

slowed through the concerted efforts of State agencies,private contractors and determined homeowners, thebattle to “control” this infectious disease is ongoing andwill continue to be as long as there are oaks inMinnesota.

Oak wilt is most common in the Upper Midwest. InMinnesota, it is most destructive in the southeast sec-tion of the state. That’s not a big surprise, since thesoutheast is home to vast acreages of native and plant-ed oaks. The greatest concentrations of oak wilt pock-ets are in and adjacent to the seven-county metropoli-tan area, but the disease occurs down the southeastborder of Minnesota and the fungus aggressivelyinfects trees in at least 15 counties (1991 survey). Oakwilt is listed as an increasing threat in an additional16 adjacent counties. In still another 31 counties, oakpopulations are at risk. These three zones of realizedand potential oak wilt outbreaks make up the majorityof the entire state of Minnesota!

Red oaks such as northern red oak and northernpin oak are highly susceptible to infection by the oakwilt fungus. Oak wilt is easily identified in red oaks bythe rapid wilting of infected trees. After symptoms firstappear, a red oak generally wilts completely in two tosix weeks, from the top of the crown down and fromleaf tip and margins to the bases of the leaves. Whiteoaks (white, bur, bicolor) range in susceptibility frommoderate (e.g., bur oak) to low (e.g., white oak).Infected white oaks die slowly, a branch at a time,often surviving for many years.

The only way the fungal causal agent of oak wiltcan cross highways, rivers and open fields is by insectvectors, primarily by sap beetles of the FamilyNitidulidae. This spread occurs infrequently, but isimportant as it is the method by which new oak wilt

infection centers are started. The beetles are attractedby the fruity smelling spore mats of the oak wilt fungus.The insects pick up fungal spores during their visits tothese mats on recently killed oaks. Several species ofthese sap beetles are also attracted to fresh wounds onhealthy oaks during spring (April, May, June). Visitationof a fresh wound by a fungus-infested beetle results inthe spread of the disease.

Cost-shared oak wilt suppression programs havebeen very successful in slowing oak wilt in many areasof Minnesota, but these programs must be continued ifthis disease is to be “controlled” at an acceptable level.Think of oak wilt as a “smoldering fire”; if not monitoredand suppressed it can explode and cause catastrophictree losses in a very short time. Stopping the spread ofthe fungus through common root systems is most impor-tant and can be done by mechanical barriers using avibratory plow with a 5-foot blade. Vibratory plowingthat severs root grafts has been very successful at halt-ing the spread of infection centers, as have other man-agement strategies such as eliminating infected trees bydebarking, burning, burying or wrapping and sealingthem in plastic.

As tree advocates, we need to spread the word so thepublic can do its part in helping control oak wilt.Important practices include:

■ Don’t transport any infected wood—such as lumber,firewood, or landscape timbers.

■ Don’t prune or wound oaks in April, May or June. Ifwounding is unavoidable, cover the wound immediately(within minutes) with a water-based paint or shellac.

■ If possible, do all oak pruning during the no-riskperiod between October and March.

In high-value white oaks, systemic injection withpropiconazole by qualified arborists may prevent spreadof the disease to trees adjacent to those that are oak wiltinfected. This can often prevent further disease develop-ment for at least two years in white oaks if they are onlyexhibiting early symptoms of oak wilt.

For more information on the Root Graft BarrierContractor List or the Oak Wilt Consultant List, contactRich Hauer at the Minnesota Department ofAgriculture/Agronomy Plant Protection Division (651-296-0592). Or, contact Jennifer Juzwik (651-649-5114)and the Minnesota Interagency Working Group on OakWilt.

Jennifer Juzwik is a research plant pathologist and projectleader with the USDA Forest Service, North Central ForestExperiment Station. Gary Johnson is an Associate Professor atthe University of Minnesota, Department of Forest Resources.

Forest ealthH

Y

ADVOCATE • SPRING ’99 7

Compensatory Pruning. . . To prune or not toprune at planting, that isthe question!

By Rich Hauer

hould tree canopies be pruned atplanting? Thirty years ago youwould have likely heard yes. Now

you will likely get a mix of yes and noresponses. Conventional wisdom says treecanopies should be pruned at planting tocompensate for root loss. Tree root systemsare reduced in size to facilitate transplant-ing bare root, balled and burlaped, and treespade-moved trees, altering the naturalroot to crown balance. Removing branchesat planting to compensate for root loss justseemed logical.

Compensatory pruning is the removalof branches to offset the loss of roots duringany period of the tree’s life. Reestablishingthe natural balance of root to crown con-ventionally meant removing one-third ofthe canopy. It was thought that transplantsurvival should increase, canopy diebackshould decrease and trees would be health-ier because of compensatory pruning. Asreasonable as this practice seemed, a scien-tific base to support it never existed. Infact, a mounting body of evidence over thelast twenty years finds that compensatorypruning does not benefit newly transplant-ed trees.

To understand why compensatorypruning is not beneficial, let’s travel backover 20 years to a tree nursery inOklahoma. A research team lead by Dr.Carl Whitcomb was conducting a weed con-trol study. As part of the research plan, treecanopies were pruned back at transplant-ing– since this was the standard practiceany respectable arborist and horticulturistwould do. However, Mother Nature inter-vened! A rainy spring season prevented

compensatory pruning in 40% of the trees.By the time the nursery fields dried andworkers could resume work, the trees hadstarted their spring flush of growth. It wasdecided not to prune the remainingunpruned trees. During the first growingseason a fortuitous finding occurred:pruned trees grew slower and had greatermortality. This certainly flew in the face ofconventional wisdom that trees pruned tocompensate for root loss should do better.Perhaps the observations were merely dueto species differences. Trees within eachspecies were treated equally; three specieshad all trees pruned and two species hadno trees pruned.

Follow-up experiments were conductedto confirm if the earlier findings were mere-ly due to species differences or if compen-satory pruning was truly not beneficial. Ina total of 11 different species, subsets oftrees were either not pruned or pruned toremove 15%, 30% or 45% of the canopy.Each treatment was replicated 12 timesand tree responses were evaluated for twoyears. Again, compensatory pruning wasfound to be not beneficial. Since then three

Dispel a ythM

Pruning should be directed ateliminating multiple codominantleaders and damaged and rub-bing branches, evident in thespecimen above, rather thanarbitrarily compensating for root loss.■ ■ ■

S

GARY

JOHN

SON

SPRING ’99 • ADVOCATE8

mended. For example, one- and two-inchcaliper trees have less root loss andrecover faster than trees two inches tothree inches in stem caliper. Mulchingtrees to a two- to three-inch depth is rec-ommended as it helps to conserve theprecious water.

To prune or not to prune at plant-ing—that is the question! Removingbranches to compensate for root loss (i.e.,compensatory pruning) is not beneficial—that is the answer. At least five indepen-dent research studies have reached thisconclusion. The fact is young adolescenttrees require nurturing to survive andbecome prosperous adult trees. The sim-ple act of watering every couple of dayswith 1.5 gallons of water per stem caliperinch is one of the best things you can dofor newly-planted trees. Selecting struc-turally sound and healthy plants is also amust. Whitcomb said it best 20 yearsago: “Top pruning and other practices areunlikely to help an unthrifty plant and athrifty plant doesn’t need it.”

Richard Hauer is a Plant Health Specialistwith the Minnesota Department ofAgriculture, Agronomy and Plant ProtectionDivision

additional studies in other locations(Colorado and England) by differentresearch teams produced similar results.

The findings in England are inter-esting in that they suggested pruning tocompensate for root loss was not thecritical question; rather, soil moisturewas more important. When pruned orunpruned treatments were grown in adroughted condition they both grew verylittle. But when water was not a limitingfactor, pruned trees had less rootgrowth, fewer leaves and smaller leaves.Trees not pruned at planting thatreceived ample water had more leaf tis-sue to photosynthesize and a greaterability to produce plant-growth regula-tors to influence root growth.

But if compensatory pruning is notthe answer, what can be done todecrease canopy dieback, increase trans-plant survival and foster tree health?Water! It’s as simple as that. But howmuch? A conventional tree-wateringguide suggests 1 to 1.5 inches of waterevery seven to ten days is appropriate.But apparently this common wateringguideline is not any more research-basedthan the compensatory pruning assump-tion.

Research within the last five yearsfrom the Morton Arboretum and theUniversity of Florida at Gainesville sug-gests more frequent watering is optimal.Newly transplanted trees benefit fromdaily watering for the first one to twoweeks, applying approximately 1.5 gal-lons per caliper inch per watering. Forthe next two or three months, watertrees every two to three days and thenweekly until established. Remember,newly transplanted trees are absorbingwater from a diminished rooting area(i.e., apply water to the root ball). Rootsmust generate and grow into surround-ing soils before a larger soil volume canbe tapped for moisture. Trees inMinnesota will become established with-in one to one-and-a-half years for eachcaliper inch of stem. Thus, it takes twoto three years before a two-inch calipertree is established.

If you cannot adequately meet thewater requirements of newly transplant-ed trees, planting smaller trees is recom-

Branch Removal at PlantingEven though compensatory prun-

ing is not recommended, somebranches may require removal atplanting. Branches that are weaklyattached (i.e., have included bark)should be removed at planting—unless you can revisit the tree andprune it within the next few years.Also, any dead, dying, and diseasedbranches should be removed. Ifremoving these causes more than 10to 20% canopy loss, do not accept thetree. If your supplier has many treesthat require extensive pruning, itmay be best to either look for a newsupplier of nursery stock or discussquality issues with your current sup-plier. We often forget that as buyerswe can influence the quality of nurs-ery stock. Accepting inferior stockonly perpetuates more of it enteringthe market.

Multiple leaders can be aproblem in evergreens aswell as in deciduoustrees. Removing all butone of the codominantleaders is a valid pruningpractice at planting time.■ ■ ■

Pruning, from p. 7

GARY

JOHN

SON

Too much mulch

ADVOCATE • SPRING ’99 9

is not a good thing!

By Rich Hauer

ulch can be one of the best additionsfor newly planted, establishing and

established trees. Mulch moderates soil tem-peratures, keeps instruments of destructionsuch as weed whips and lawnmowers awayfrom trees, lessens soil moisture evaporation,adds organic matter to soil and supports soilmicrobial populations including mycorrhizalfungi. Storms throughout Minnesota in 1998created an enormous volume of wood chips foruse in mulching woody plants. However, toomuch mulch against tree stems or over theroot system can do more harm than good!

Have you ever observed trees growing ontop of a beaver lodge or in the crater of a vol-cano? Though this may happen, most beaverlodges and active volcanoes tend to lack trees.Yet, take a stroll in your neighborhood andyou are likely to find a case of the overzealousmulcher trying to help the tree by replicatingthese features through “beaver lodge” or “vol-cano” mulching. Fortunately beaver-lodge-encased trees do not attract beavers, nor doesvolcano mulching favor lava eruptions, both ofwhich would surely cause instant death totrees. Yet, overmulching in these ways stillhurts trees by:

■ increasing the likelihood of rodents dam-aging the stem

■ maintaining a wet environment aroundbark that promotes disease and death of barktissue

■ creating anaerobic (without oxygen) soilenvironments, and

■ decreasing the exchange of oxygen andcarbon dioxide through lenticels in the lowerstems.

Plants respire, which means they use oxy-gen to convert stored energy from photosyn-thesis to energy forms that drive plant func-tions. A lack of adequate oxygen slows or stopsgrowth and can result in the death of livingcells and plant tissue.

The effects of overmulching are not imme-diately observed. It may take a few years forthe affects to be noticed. If root and stempathogens have gained an advantage, it maybe too late to do anything.

But what can be done? First, don’t over-mulch. Recommend-

ations vary on the exact depth, ranging from 2to 6 inches. Whenusing a fine-texturedmulch (i.e., cedar barkmulch), apply a thin-

M

Proper mulchingcan be one of thebest things youcan do for yourtree.■ ■ ■

Right: the beaver-lodgemulching approach . . . anupcoming problem for the

tree in question.■ ■ ■

RICH

HAU

ER

RICH

HAU

ER

SPRING ’99 • ADVOCATE10

New and Controversial Research on Typesand Uses of Mulch in the Landscape

A summary of a MN Student Society ofArboriculture, Professional Seminar Series present-ed by Dr. Jeff Iles, Iowa State University

Maybe it’s been just a general aversion to more amor-phic surfaces? Maybe it’s been the general belief that organicis always better? Or, maybe it’s been just a thinly veiled prej-udice toward the aesthetic qualities of anything other thanearth tone in color and soft in texture? Green professionalsand especially tree lovers have generally promoted organicmulches on the basis that they improve plant health, andavoided mineral (rock) mulches, claiming that they are atbest an eyesore and at worst detrimental to tree health. Butis that an undeniable fact? Would it hold true if scientificallytested?

Dr. Jeff Iles, a professor of horticulture with the IowaState University Extension Service, put that commonly heldbelief to task. In a field experiment located at the Universityin Ames, Iowa, he compared two general types of mulch—organic and mineral (rock)—against a control, bare soil, anddiscovered something rather disconcerting. Rock mulchesweren’t harmful to tree health, at least on a short-termbasis!

The soil under the mineral mulches (lava rock, pea grav-el, crushed brick, Carmel, river rock) was cooler thanexposed soil, as expected, but warmer than soil under organ-ic mulches (wood chips, screened pine, shredded bark), againas expected. Both types of mulches kept the soil more moistthan bare soil. Even though organic mulches were statistical-ly more moist, it wasn’t a huge difference from the mineralmulches (31-32% vs. 29-31%). And as far as soil pH was con-cerned, the soil under the various mineral mulches remainedmore acidic than those under organic mulches.

Trees under mineral mulches actually grew more in bothstem caliper and height than most of those mulched withorganic materials or the bare-soiled controls—not a tremen-dous amount, except for the quantity of leaves produced.Those trees with mineral mulches performed very well com-pared to the organic mulches. Every mineral-mulched treeput out more foliage mass than every organic mulched tree!

So, is it time that we all rake away the wood chips andreplace our “natural” mulches with rocks? That wasn’t Dr.Iles’ message. His research was with one tree species(Fairview Flame red maple), growing in good Iowa loam,from 1997-1998. Jeff made no sweeping generalizations fromthis data. Rather, he posed the question that maybe our gen-eral opinion of rock mulch as bad mulch for tree health maynot be so accurate. More research is definitely necessary: dif-ferent trees, different soil types and more growing seasons.But it does look like another myth may be challenged . . .even if you don’t like the way rock mulch looks!

Gary Johnson, University of Minnesota, Urban and CommunityForestry

ner amount (2 to 3inches). Coarse-tex-tured mulch (i.e., twig-gy mulch) can be

applied to a thicker depth (3 to 6inches). Whatever depth is applied,keep mulch away from the stem oryou will face problems with rodentsor pathogens.

Second, if a tree is overmulched,simply spread out the material toexpand the diameter of themulched area. Your tree will be hap-pier and healthier!

Third, if you know of trees thatare forced to grow through beaver-lodge or volcano-mulched environ-ments, educate the practitioner ofthe ramifications of the situation.

Richard Hauer is a plant health specialistat the Minnesota Department ofAgriculture.

Mulch, from p. 9

Left: the mulchvolcano ■ ■ ■

✓ Don't over-mulch.

✓ Spread outexcess mulch.

✓ Spread theword to others.

RICH

HAU

ER

NEWS RELEASE

April 7, 1999

For Immediate

ReleaseContact: Jo Ann Reed

A New Arboretum

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ADVOCATE • SPRING ’99 11

Spreading the Word About Your Tree Events

ublicity through the media can be a pow-erful tool in building awareness, creating

support and providing a positive image for com-munity tree programs. While a variety of toolscan help spread the news, the News Release(also called Press Release) is an easy and prac-tical way to attract attention to your program.It’s generally written to announce a specialevent, but can also be used to call attention toon-going programs of community interest.

To be easily understood by reporters, newsreleases should use a standard format and fol-low guidelines that include:

■ The HeadingWrite NEWS RELEASE at the top of your

sheet.

■ The DateBe sure to include the date at the begin-

ning of your release. If the news should bereleased now, say For Immediate Release. If it isto be released by a certain date, say For Releaseby ________.

■ The ContactAlways include the name and telephone

number of a person reporters can call if theyhave questions or need more information. E-mail and website addresses, if you have them,can be included as well.

■ The HeadlineTry to summarize the information into a

sentence that will grab the interest of thereporter who receives it

■ The FormatSummarize the most important elements in

the first paragraph, answering the five “W” andthe “H” questions. (Who, What, Where, When,Why, How). Add detail in the following para-graphs. If a reporter has to cut copy, he or sheshould be able to cut later paragraphs withoutlosing important details.

Be as clear and concise as possible.Describe what a visitor to this event will actual-ly see. Be precise about location (room num-bers, locations within a park, etc.).

Intelligently

crafted news

releases are

powerful

tools.

P ■ Human InterestInclude a quote or two from key people

involved in the event. Quotes draw the readerby adding a personal touch to the story.

■ The LengthLimit your release to one or two pages, dou-

ble spaced and with wide margins. If there is asecond page, center the word “more” at the bot-tom of the first page to make sure readers seeall the information. At the end of the release,center ### or -30-. It is the reporter’s signal for“ the end.”

■ The Follow-UpAfter sending your news release, make a

follow-up call. Reporters are often pressed fortime and juggling a range of stories and dead-lines, so organize what you want to say beforedialing the phone. Practice or jot down two orthree sentences that summarize why the storyis important. Don’t just ask if they got therelease; ask if they need more information.Offer to help in any way you can. Whether welike it or not, media people have the power todecide what is news and how they will presentit. Be courteous and prepared to meet thereporter’s needs.

■ Photo ReleasesIf you send a photo along with your news

release, make sure you have permission fromeveryone in the photo to use the picture. Tape a short paragraph on the back of the photo-graph to identify people and explain what ishappening.

■ Photo OpportunitiesIf your goal is to get media coverage for a

specific event, you might want to note photoopportunities available to a reporter if he or shevisits the event (children planting trees, experttree climbers, etc.).

Creating a good media program is morethan just sending a news release now and then.Try to establish a relationship with media peo-ple who cover community interest stories andthen give them what they want, using the toolsthat work for them.

SPRING ’99 • ADVOCATE12

CommunityPlanting Projects:

Mobilizing theVolunteers

The project has been fundedas a five-year program in coopera-tion with the St. Paul Foundationsince 1995. There will be a closureevent this year, but plans arebeing developed to continue green-ing the banks.

Assistant Director KathyDougherty offers these tips for asuccessful volunteer effort:

■ Make the event really simplefor volunteers (easy sign-in, train-ing and direction . . . people wantto have fun and to help).

■ Limit the event to a few hours. . . not all day.

■ You simply can’t plan enough.Time spent planning and pre-thinking every part of the event will help prevent disarray later.Volunteers will feel good aboutbeing involved in an organized and worthwhile project, andmany will come back year afteryear.

For more information: KathyDougherty, 651/224-9885.

Beautifying the Inner City

Tree advocate/volunteerBonnie Lawrence is well knownand respected for her feisty com-mitment to St. Paul’s communityforest. Many recognize her as acatalyst for building citizen aware-ness and enforcement of the city’santi-stapling ordinance, but she isalso a leader in promoting inter-city planting. Among other pro-jects, she has been heavilyinvolved in Arbor Day planting atCentral High School (1992), pro-jects at St. Paul’s Dunning Field,community gardens, boulevardplanting and roadside beautifica-tion. Her group’s planting on I-94right-of-way near Concordia was afirst-of-its kind project and openedmany eyes to new possibilities forcity beautification.

Motivating interested citizensinto action is Bonnie’s forte.

olunteers are the life-forcebehind hundreds of plantingprojects across the stateeach year. A lot can be

accomplished in a short time, andthe community tends to get invest-ed in new ways when citizens workon projects themselves. The struc-ture and organization of projectsvary from one to another, but thesuccess of each is directly linked toeffective use of volunteers. Read onand glimpse some ideas from estab-lished projects that can work foryou, too.

Greening the Great River Park

Operating as an ecologicalrestoration project along theMississippi River banks as theymeander through St. Paul, thisplanting partnership may draw 400or 500 volunteers on a single day.Business owners, schools, churches,scout troops, state agencies and thegeneral public take part in plantingevents twice a year—in spring and

in fall. The project includes plant-ing on both private and pub-

licly-owned land.As with any volunteer

effort, much of the coordinationis done far in advance of the workday. The event is publicized in avariety of ways, but also includes amailing to a list of about 4,000repeat volunteers.

On the day itself, the entirework area is divided into work orplanting units. Ten to 15 volunteersmake up each unit, along withtrained supervisor. Sign-up sheetsbecome the work unit. There is a15-minute orientation (guidelines,how to plant, etc.) followed by one-and-a-half to two hours of work.Lunch is donated; beverages andportable toilets are provided. Manychildren are involved and smallertasks are planned so even youngchildren can participate. Familiesenjoy doing the project togetherand intergenerational groups are common.

V

ADVOCATE • SPRING ’99 13

Because so many of her projectshave involved public property,Bonnie stresses the need to makesure communication and supportfrom public officials are in place asprojects are planned and imple-mented. Make sure you have morethan just a vision—do someresearch and prepare to sell yourideas to local officials. This year’splanting can literally be destroyedby next year’s maintenance crewswhen communication isn’t clear.Or, one project can be planted overor interrupted by someone else’ssubsequent project when informa-tion is lacking.

Expertise is often needed fromcommunity tree or garden profes-sionals in the types of plantingBonnie does. Species and siteselection are especially importantbecause the stresses of city living(salt, watering irregularities,emissions, people, pets, etc.) posechallenges to any planting.

For more information: BonnieLawrence, 651/646-3433.

Beautifying Rural Roadsides

The Minnesota Department ofTransportation has a partnershiprole with local communities asthey spruce up their roadsideswith flowers, native grasses andtrees. Highway 11 as it runsthrough Warroad and other north-ern communities is an example.Ringleaders in the community pro-vide impetus to the project initial-ly. Once a partnership is signedbetween MnDOT and the commu-nity, MnDOT provides plantingand project expertise and workswith local leaders to help themaccomplish their goals. They helpmake site and species selections,make sure maintenance needs andother rules are followed, pay forthe nursery stock, help train andsupervise volunteers and overseegroup safety. The latter is a mainconcern because plantings areoften done near busy roads.

Volunteer recruitment andcoordination is handled by the localcommunity. MnDOT’s Bob Slatersays community dedication andcommitment to carry the projectthrough are keys to a successfulproject. He recommends keepingvolunteer projects small, especiallythe first year. Some towns areimplementing projects in phases,and it works well. Planning specifi-cally how volunteers will be used,organizing and supervising thework groups and supporting thevolunteers in their efforts are vital-ly important.

For more information on MinnesotaDepartment of Transportation roadsideenhancement volunteer projects: BobSlater, Forester, at 651/779-5104 orScott Bradley, Landscape ProgramCoordinator at 651/779-5076.

Ramsey Shademakers

The City of Ramsey has a coreof local homeowners and citizenswho make up an on-going volunteergroup that advocates for and plantstrees. Dubbed the Shademakers,the dozen or so members meetmonthly at member’s homes.Socializing is part of the fun as gar-deners, city officials, tree profes-sionals and interested others cometogether to plan and implementcommunity planting projects. Aplus for the group is that severalShademakers are tree-related pro-fessionals who live in the area. Onemember is developing a back yardnursery at his home, which offersunique opportunities to work withlocal seed and stock.

The Shademakers group is awin-win situation for Ramsey. Thegroup promotes community forestprojects, helps train citizens intree-related areas and helps imple-ment the Ramsey Tree Sale eachspring.

For more information: Bruce Bacon,City of Ramsey Forester: 612/427-1410.

Celebrate Arbor Day!

“Planting Living History: AnArbor Weekend” is the theme ofthis year’s Arbor Event at the OliverKelley farm near Elk River. Here’s agreat way to spend a Sunday withfriends or family, step back in histo-ry and celebrate trees at the sametime.

“Planting Living History” isheld in conjunction with theSherburne County Tree Board,MnSTAC, the City of Ramsey, theMinnesota Historical Society, DNRForestry and a host of state, countyand local agencies/groups. Visitorscan participate in the ceremonialArbor Day tree planting, view a pro-gram on native prairie restorationthat includes a controlled prairieburn and take self-guided tours onthe natural history trail system thatruns along the Mississippi River. Aninformation fair at the Kelley FarmInterpretive Center promises some-thing of interest for everyone, andvisitors can take home seedlings toplant in honor of Arbor Day.

The Kelley Farm is located 21/2 miles southeast of Elk River onU.S. Highway 10. The celebration ison Sunday, May 2 from noon to 5PM and admission is free. For moreinformation call 612/441-6896.

SPRING ’99 • ADVOCATE14

About MnSTACThe Minnesota

Shade Tree AdvisoryCommittee (MnSTAC)was established in 1974by a group of concernedcitizens to address thehealth and well being ofcommunity forests.MnSTAC provides aforum where people forgea collective vision for thefuture of Minnesota’scommunity forests and:

• advocates for publicand private communityforestry interests

• unites for theexchange and dissemina-tion of ideas and infor-mation

• serves as the StateUrban Forest Council toadvise the State Foresteron the implementation ofstate and federally-fund-ed programs.

MnSTAC is recog-nized throughoutMinnesota and the coun-try for its expertise,advice, coordination andsupport for communitytrees. It is an organiza-tion of diverse individu-als who represent abroad spectrum of tree-related interests. It fos-ters and supports localcommunity tree programsacross the state sohealthy communityforests are fully integrat-ed into community devel-opment, infrastructure,education and manage-ment.

The MnSTACresources listed hereencourage your calls,questions and sharing ofideas.

MNSTAC BOARD OF DIRECTORSPresident: Glen Shirley, City of Bloomington—612/948-8760 (Fax: 612/948-8770)

Vice President: Kirk Brown, Twin Cities TreeTrust—612/920-3239Dan Gullickson, MN Dept. of Transportation —651/779-5084Katie Himanga, Heartwood Forestry —651/345-4976Ken Holman, DNR Forestry—651/772-7565Gary Johnson, U of M Forest Resources—612/625-3765Mike Max, EnvironMentor Systems, Inc.—612/753-5505Dwight Robinson, MN Dept. of Agriculture—651/296-8578Mark Stennes, Top Notch Treecare—612/922-3239

MNSTAC COMMITTEES AND TASK FORCES

Arbor Month PartnershipChair: Don Mueller, DNR Forestry—651/772-6148

Constitution and Election Chair: Ken Simons, Ramsey County Parks—651/748-2500

Education and Research Chair: Gary Johnson, U of M ForestResources—612/625-3765

Forest Health Chair: Steve Kunde, Kunde Company—651/484-0114

Legislative Chair: Mark Schnobrich, City of Hutchinson—320/234-4459

Outreach Co-Chairs:Peter Bedker, Treescapes—612/682-9562Mike Max, EnvironMentor Systems, Inc.—612/753-5505

Planning Chair: Dave DeVoto, Stacy, MN—612/462-3347

Publicity and Awards Chair: Terri Goodfellow-Heyer, MN StateHorticultural Society—651/643-3601

Scholarship Chair: Ralph Sievert, Mpls. Park and Rec.Board—612/370-4900

Tree Emergency Response Chair: Katie Himanga, Heartwood Forestry—651/345-4976

Tree Preservation Task ForceChair: Paul Buck, City of Plymouth—612/509-5944

Wood Utilization Task ForceCo-Chairs: Mike Zins, U of M Arboretum—612/443-2460 Ext. 247Jim Hermann, Mpls. Park and Rec. Board—612/370-4900

Regional Shade Tree Advisory CommitteesTo add more voices to the forumand encourage networking moreeasily at the local level, threeregional MnSTAC units are inplace.

Southeast STACSoutheast STAC represents com-munities in the eleven counties thatare part of the Hiawatha ValleyResource Conservation andDevelopment Area. For informa-tion, contact:Chair: Henry SorensenAsst. Pub. Service Director, City of Red Wing651/385-3674Sec./Treas.: Katie HimangaHeartwood Forestry, Lake City 651/345-4976

Headwaters-Agassiz STACHASTAC, the Headwaters-AgassizShade Tree Advisory Committee,was formed about a year ago as aregional branch of MnSTAC. TheNW Regional DevelopmentCommission is the fiscal agent. Forinformation, contact:Chair: John JohnsonCity Forester, City of Thief River Falls218/681-1835Sec./Treas.: Jeff EdmondsDNR Forestry, Bemidji 218/755-2891

West Central STACWest Central STAC started in 1997to help communities in the north-west region share ideas, informa-tion and local success stories inmanaging community trees. Forinformation, contact:Chair: Bob FogelDirector of Parks, City of Moorhead218/299-5340Sec./Treas.: Dave JohnsonDNR Forestry, Detroit Lakes 218/847-1596

STAC

irec

torie

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ADVOCATE • SPRING ’99 15

Events andConferencesMay 1-5—4th International

Symposium on UrbanWildlife, Tucson, AZ.Contact Bill Shaw 520/621-7265.

May 13—Trees, People, andthe Law, St. Paul, MN.Contact NADF 402/474-5655.

June 6-9—Balancing WorkingLands and DevelopmentNational Conference,Philadelphia, PA. ContactCindy Delaney 802/655-7215.

June 28-30—Building withTrees National Con-ference, Nebraska City NE.Contact NADF 402/474-5655.

Aug. 1-4—InternationalSociety of Arboriculture75th Annual Conferenceand Trade Show, Stamford,CT. Contact ISA 217/355-9411.

Aug 5-8—Midwest Environ-mental EducationConference, Stillwater, MN.Info at http://www.seek.state.mn.us/cal/calendar.cfm

Aug 31-Sep 5—9th NationalUrban ForestryConference, Seattle, WA.Info at http://www.amfor.org/

OpportunitiesThrough June, 1999

MnReleaf Forest Healthgrants available. ContactDNR Region Office or612/772-7925.

New PublicationsAfter the Storm: What to dowith Storm Damaged YardTrees. Revised fact sheet.Contact MN DNR–ForestryDivision 651/772-7925.

Citizen Monitoring for AsianLong Horned Beetle (ALHB).Draft write-up available.Contact Teri Heyer 651/649-5238 to review copy.

Landscape Design andSelected Species for Residen-tial Sites (5 brochures). 1998.

— Evergreen Shaded GardenLandscape Design

— Native Shade GardenLandscape Design

— Prairie Garden LandscapeDesign

— Suburban Garden LandscapeDesign

— Wet Meadow GardenLandscape Design

Contact MN DNR Forestry612/772-7925.

Internet• International Society of

Arboriculture:http://www.ag.uiuc.edu/-isa

• Minnesota Department ofNatural Resources:http://www.dnr.state.mn.us

• National Arbor DayFoundation:http://www.arborday.org

Tree otpourri

Wilt Diseases ofShade Trees: ANational Conference

This conference, spon-sored by the AmericanPhytopathological Society,will be held in St. Paul,Minnesota, August 25-28,1999. It consists of 2.5 daysof presentations on bacterialleaf scorch, pine wilt disease,oak wilt, Dutch elm disease,Verticillium wilt, phytoplas-mal diseases and Fusariumwilt followed by an all dayfield trip. For more informa-tion visit http://www.scisoc.org/opae/shortcourse/ or contact Cindy Ash, cash@scisoc.org, or 651/454-7250.

P Urban and Community Forestry Calendar

Arbor Day Farm: A Good Place to Visit!When you’re in the mood for a good tree-related semi-

nar, a special holiday event or a place to simply get awayfor a little rest and recreation, consider the Arbor DayFarm and Lied Conference Center in Nebraska City,Nebraska. Managed by the National Arbor DayFoundation, the conference center is the only educationcenter of its kind in America with staff and programs dedi-cated to tree planting and environmental stewardship. Afull range of tree-related conferences, seminars and work-shops are offered year around. Holiday events for friendsand families include special celebrations for Mother’s Day,Memorial Day, Independence Day, Labor Day,Thanksgiving, Christmas and New Year’s Eve in 1999,plus an Applejack Festival and a Civil War Re-enactment.Overnight stays are popular, moderately priced and avail-able for use by all.

Arbor Day Farm was once the agricultural estate ofArbor Day founder J. Sterling Morton. Based on therich history of the land and Morton’s lifelong commit-ment to trees, the Farm is now a National HistoricLandmark.

There is much for tree lovers to see and enjoy.Thousands of trees fill the landscape. A state-of-the-artfuelwood plant is open for tours. The arboretums, wind-breaks, agroforestry demonstration area, appleorchards, hazelnut research field and fuelwood planta-tion at Arbor Day Farm reflect the National Arbor DayFoundation’s commitment to the best methods of treeplanting and care.

For information or reservations at Lied ConferenceCenter or Arbor Day Farm, call 1-800-546-5433.

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A quarterly newsletterpublished by theMinnesota Shade TreeAdvisory Committee.

Managing Editorial Group:MnSTAC EducationCommittee; Gary R.Johnson, Chair

Editor-in-Chief: Jan Hoppe

Design: Jim Kiehne

Material in this newsletteris not copyrighted.Reproduction for educa-tional purposes is encour-aged. Subscriptions arefree. Articles, news items,photos and videos are wel-come.

This publication was pro-duced with the support ofthe U.S.D.A. ForestService, NortheasternArea; State and PrivateForestry.

Address inquiries to:

Jan HoppeMinnesota Shade Tree

Advocate115 Green Hall1530 Cleveland Ave. N.St. Paul, MN 55108

Printed on recycledpaper using soy-basedinks.

Adding Color to the LandscapeAs homeowners, business people and

community planners thumb through seedcatalogs each spring, they are ofteninspired to add more color or structure(walls, walks, etc.) to their landscapes.Sometimes, that color comes through creat-ing flower beds, ground cover and foliageunder existing trees. The structure mayrun over or through tree roots. It’s impor-tant to help people remember the needs ofthe trees as they dig, grade and plantaround them. Key points:

■ Anything done under a tree that dam-ages roots or changes the conditionsaround them can be harmful or even dead-ly to the tree. Adequate access to water,nutrients and air is critical for root andtree health. This access can be changedthrough compacting the soil, covering theroots with non-porous materials, changing

watering patterns, adding mulch,applying herbicides and fertiliz-ers, digging and cultivating,changing the soil level, puttingin new plants that compete for

nutrients in the soil and more.Roots are fragile, especially in

young trees and in those species with shal-low root systems.

■ Don’t make drastic changes all at once.Give the tree time to adapt if you plan amajor planting or structural project.

■ Try to maintain the existing gradearound trees. Lowering the grade can

damage roots; raising it will affect thewater drainage and amount of oxygen theycan absorb through the soil. Tolerancedepends on the type of tree, the soil itselfand the effectiveness of surface draining.Many trees will tolerate up to six or eightinches of additional soil or fill while othersare threatened by two or three inches. Ifgrading results in a ground level too highfor existing trees, retaining walls severalfeet out from the tree trunk might be anoption. Carefully prepared shallow raisedbeds can sometimes be constructed on partof a tree’s root area. A coarse plantingmedium that allows air and water to movethrough easily is important. A mixture ofone-third loam, one-third coarse sand andone-third composted organic material byvolume is good.

■ Consider containerized plants undertrees.

■ Structural changes (walkways, walls,boardwalks, etc.) need to be carefullyplanned and placed to minimize root dam-age. Boardwalks can be effective alterna-tives to paved walkways. They don’trequire the excavation that paved surfacesdo and are often as suitable as paved walk-ways.

Armed with knowledge about the needsof trees, adding color and structure to thelandscape is usually possible. A tree careprofessional can give specific advice.