Transplant Shock: Disease Or Cultural Problem?

University of KentuckyCollege of AgriculturePlant Pathology ExtensionCooperative Extension ServiceUniversity of Kentucky College of Agriculture, Food and EnvironmentPPFS-OR-W-19Transplant Shock:Disease or Cultural Problem?Nicole Ward Gauthier & Cheryl Kaiser, Plant PathologyMike Klahr, Horticulture Extension AgentIntroductionWhen trees and shrubs are moved from one growingsite to another (e.g. from nursery to landscape),they endure stress. If care is taken to minimizestress through proper transplanting techniques andmaintenance, plants are likely to recover rapidly andbecome well-established in their new sites.Unfortunately, the opposite usually occurs. Treesand shrubs suffer “transplant shock” (Figure 1) fromimproper transplanting or maintenance, and recoveryis hindered. Under stressful conditions, plants areunable to recover, continue to decline, and eventuallydie. Although plant diseases may be responsible,transplant stresses are most often the culprit of deathor decline of newly planted trees and shrubs.Woody plants may take as long as 3 to 5 years toestablish in their new locations and to recover fromtransplant stresses. Visible leaf and shoot emergenceare not indicators of plant establishment. Transplantsare not considered established until primary rootsexpand into native surrounding soil, branch out, andproduce sufficient feeder roots on their tips.If trees fail to regenerate new, healthy roots orfail to establish root systems in new planting sites,transplant shock often results. Such root-relatedproblems may be traced to one or more factors:stresses which occurred when plants were removedfrom original sites, injury during transit, improperplanting techniques, and/or poor cultural practices.Figure 1. Dieback due to transplant shock often begins withdeath of scattered limbs. (Photo: Jason Sharman, Vitalitree,Bugwood.org)Agriculture & Natural Resources Family & Consumer Sciences 4-H/Youth Development Community & Economic Development

Figure 2. Leaf scorch is caused by inadequateavailability, which is common in poorly-maintained(Photo: Nicole Ward Gauthier, UK)watertrees.Figure 3. Premature fall coloration and early leaf dropcan result from stresses of transplant shock. (Photo:Ohio Nursery & Landscape Association, Bugwood.org)Figure 4. Treesstressed from transplant shock aremore susceptible to diseases, such asThyronectria(William Jacobi, Colorado State University,Bugwood.org)canker.Figure 2Figure 3Transplant ShockSymptoms of Transplant ShockSymptoms of transplant shock can resemble diseaseand other stresses. Decline Canopy thinning Dieback (Figure 1) Leaf scorch (Figure 2), tip burn Reduced winter hardiness Poor leaf color Premature fall color (Figure 3) Limited stem growth, stunting Limited flowering Premature defoliation/leaf drop Delayed leaf emergence in spring Secondary disease problems (Figure 4) Secondary insect problems Excessive seed or cone productionCauses of Transplant ShockCauses of transplant shock and related stresses canrange from pre-plant care to post-plant maintenance:Poor plant material Species/cultivar not suited to Kentucky climate.Figure 4 Plant not healthy and vigorous due to previousstress, insects, or disease damage. Root ball too small for amount of top growth. Plant roots dried out between digging andtransplanting, resulting in root damage and/ordeath. Leaves and twigs of plant not protected fromwind during transport from nursery to landscape.Undesirable growing site Soils poorly drained – including both surfacedrainage and internal drainage (e.g. subsoil orother high clay content soils). “Wet feet” resulting from locations near gutterdownspouts or other low-lying areas. See WetFeet in the Landscape (PPFS-OR-W-04) Compacted soil, resulting in reduced rootgrowth, lack of oxygen and air exchange, andreduced water penetration. See Trees andCompacted Soil (HO 93) Shade loving tree or shrub planted in full sun,or vice versa.Poor transplant techniques Root ball allowed to dry-out before planting. Root ball allowed to freeze prior to planting.

Figure 5. Wirefrom tags and guides can girdle branches and trunks if notremoved at time of planting.(Photo: John Hartman, UK)Figure 6. Burlap does not readily degrade in planting holes and should beremoved from plants before installation. This synthetic “burlap” materialprevented roots from expanding beyond the original rootball. (Photo:Cheryl Kaiser, UK)Figure 5Figure 7aFigure 7a. Encirclingrootsoften continue this growthhabitafterPoor follow-up cultural practices Improperwatering—littleorno watering, excessive watering(especially problematic in heavy claysoils) or frequent light sprinkling. Application of high levels ofnitrogen, resulting in excessive topgrowth compared to root growth (rootto-shoot ratio).Figure 6 Mechanical injury during digging, moving, ortransplanting. Planting hole too small, crowding roots. Sides of hole “glazed,” preventing rootexpansion. Twine or wire from nursery tags and guides leftintact; girdling roots, trunk, or limb (Figure 5) Burlap or synthetic (non-biodegradable)“burlap” (Figure 6) or twine left around root ball.installation.(Photo: Ambrose Labs)Figure 7b. Afteryears ofencircling, roots can girdlestructural roots or trunks.(Photo: John Hartman, UK) Container-grown plant is rootbound, and roots continue to growaround or spiral (Figure 7), ratherthan growing outward. Planted at the wrong depth, eithertoo deep or too shallow. Failure to protect young tenderbark from exposure to temperaturefluctuations in winter, leading tosunscald and frost crack injury(Figure 8). Tree wrap left on trunk more thanone season. Excessive use of fertilizer at plantingtime, resulting in root “burn.” Mower or string trimmer damage(Figure 9).Recommendations for Reversing TransplantShockPrevention is the key to minimizing transplant shock.Only healthy, hardy landscape material shouldbe purchased and installed into landscapes. Thefollowing steps are important for reducing transplantstress and may reverse transplant shock symptoms:Figure 7b

Figure 8Figure 8. Sunscald damageoccurs during early springon thin-barked trees.Figure 9. Mowerdamagecauses wounds that girdletrunks. (Photos: NicoleWard Gauthier, UK)Figure 9Proper Transplant ProceduresImproper tree planting is one of the leading causesof tree decline and death. Proper planting methodsfor nursery stock will vary slightly based on growingtechnique and type of nursery stock.Types of Nursery Stock AvailableWoody plants are commonly produced and sold inthree different forms: container-grown, balled-andburlapped, and bare root (Figure 10). Containergrown trees and shrubs are grown, established, andsold in containers or pots. Balled-and-burlapped(B&B) plants, on the other hand, are grown in fieldbeds and then dug prior to sale. Root balls withsurrounding soil are wrapped in burlap for transportto planting sites. Bare root plants are also grown infields or prepared beds. However, they are dug duringdormancy, and soil around roots is removed. Plantsare kept in cold storage (40 F) until they are sold.Refer to Table 1 for a comparison of the three formsof nursery stock available. Relocate plants to more appropriate sites(during dormant season). Prune or remove dead and dying branches. Water thoroughly during dry periods with theequivalent of 1 to 1½ inches rain per week. Fertilize according to soil test results (notrecommended during year-1, seeFertilization, below). Mulch. See Mulch Myths (HO-106).Figure 10aHandling Plant MaterialTrees and shrubs should be installed as soon aspossible after delivery, regardless of whether theyare container-grown or field-dug. Plant materialshould be protected from physical damage, freezingFigure 10bFigure 10cFigure 10. Planting material is available as (a) container grown, (b) balled-and-burlapped or (c) bareroot. (Photo: CherylKaiser, UK)

Table 1. A comparison of the characteristics of the types of nursery stock available.Container grownGrown in containersBalled-and-BurlappedGrown in field; must be dugRoot system completely intactRoot system cut and reduced whendugPlants can be kept for extendedPlants can only be held for shortperiods before plantingperiods of time after diggingSoil and containers provide protection Soil around roots provides limitedfor rootsprotection from dryingCan be planted throughout thePlant during dormancy in fall or ingrowing or dormant seasonsearly spring before active growthbegins.Easy to transport and handle during Heavy due to weight of field soil;moving; soilless media is lighter than usually not shipped long distancesfield soilIf pot-bound, roots may spiral, causing Roots are severed at edges of rootballgirdlingDifficult to inspect entire root system Difficult to inspect entire root systemtemperatures, heat and drought, or other adverseconditions. Dampened sawdust, loose compost, orpotting mix is packed around plants during shippingand should be kept moist at all times.Primary sites of root regeneration are severed rootends of field-dug plants (balled-and-burlappedand bare root plants). Therefore, soil around thesereduced-size root balls should remain moist. Plantsshould not be left standing in tubs of water; athorough soaking with a hose is usually sufficient.If bare root or balled-and-burlapped plants cannotbe installed immediately after purchase, they maybe “heeled” into a bed of damp sawdust or loosecompost that completely covers root balls. Beforeplanting, soak roots in water for up to 30 minutes torehydrate.Site SelectionGrowing sites should be carefully selected. Considernot only aesthetics, but also sites where plants willadapt and thrive. Trees and shrubs should be able toreach full maturity without growing into overheadwires, buildings, fences, other plants, driveway areas,etc. Sun and wind exposure should also be takeninto account before planting. Choose a site withfertile, loose, well-drained soil that lacks a hardpanor compacted layer (deep soil). Refer to Trees andCompacted Soils (HO-93).Bare rootGrown in field; must be dugRoot system cut and reduced whendugPlants need to be planted promptlywhile they are dormantAbsence of soil around roots increasesrisk of dryingPlant during dormancy before activegrowth beginsCan be shipped at lower costs due toabsence soilsNeed to spread roots out in plantingholeCan inspect and prune root systemTime of PlantingIdeal planting times include: dormancy, after leafdrop in autumn, and before budbreak in early spring.These dormant plant phases optimize survivalrates by providing opportunities for early rootdevelopment while soil moisture is high. Autumnplantings provide more time for new root systemsto become established, since roots continue to growthroughout fall and winter months (as long as groundis not frozen). Resulting extended root systemsincrease water uptake during hot, dry summerconditions. In contrast to autumn installations, earlyspring plantings may be preferred during extremelycold winters or during winters with numerousfreeze-thaw cycles. Early spring installations arealso recommended for broadleaf evergreens suchas hollies, boxwoods, and rhododendrons. Becausethese plants do not drop leaves in winter, they maylose large quantities of water through leaves. Dryingwinds cause desiccation and drying of leaves andother plant tissues.Planting HoleBefore digging, consider locations of undergroundutilities; contact utility location services by dialing8-1-1 (electric, cable, water, and other providers).Hole SizePlanting holes should be dug twice as wide as the