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Tree vigor is important because more leavesmean more carbohydrate production and largercherries. The production o high-qualitycherries requires a gross canopy lea area-to-ruit(LA:F) ratio o at least 200 cm2 o lea area perruit, which roughly translates to ve leaves perruit (Whiting and Lang, 2004). Trees with alower LA:F ratio are unable to manuactureenough carbohydrates to produce premiumcherries.

Pruning strategies or trees on productive root-stocks should ocus on the ollowing: Thinning cuts to remove pendant (downward-

hanging) and weak wood and to improve lightpenetration into the tree

Stub cuts to reduce crop load and renew spurs Heading cuts to encourage branching (lea

production) and reduce crop load

Thinning cutsEach year, begin by removing any pendant or

small-diameter wood at the point o its origin.Typically, these branches overset and producesmall cherries. Removing these branches inthe dormant season can eliminate a signicantamount o small cherries beore they develop.

PNW 592 January 2007

Four Simple Steps to Pruning Cherry Trees onGisela and Other Productive RootstocksL.E. Long

Also reduce branches in the top o the tree andon the perimeter to a single shoot.

These thinning cuts will allow light to reachthe inner and lower portions o the tree. Onlyleaves in ull sunlight can photosynthesize atmaximum capacity.

Stub cuts

The current seasons crop can be reduced byheading with stub cuts. Stub cuts also replacebranches and renew old spurs.

The highest quality cherries grow at the base olast years growth and on young spurs. Thereore,no spur should be older than 5 years old. To keepspurs within this age range, stub back and renew20 percent o all ruiting branches each year.

Adequate light must reach the area around thecut in order or a new branch to orm. For thisreason, cut branches located near the tree base to alonger stub than those near the tree top. Stubs canrange rom 3 inches to 2 eet in length, dependingon the position o the branch in the tree.

A Pacic Northwest Extension publication

Oregon State University University of Idaho Washington State University

Pruning and training trees on productive

rootstocks, such as Gisela 6 or 12, requires

techniques that are completely counter to

pruning trees on Mazzard rootstock. When producing

cherries on Mazzard rootstock, orchardists must

constantly think about how to encourage precocity

and productivity in the tree, whereas when producing

cherries on productive rootstocks, they must focus on

reducing crop load and increasing vigor.

Lynn E. Long, Extension faculty (horticulture), Wasco

County, Oregon State University.

C

orianneDaman

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Heading cutsLateral branching is necessary to produce

enough leaves to produce a crop o premium cher-ries. Because cherries are characterized by strongapical dominance, lateral branches will not orm

readily without grower intervention, although thedegree o natural branching varies among variet-ies. Heading cuts are the most common techniqueused to overcome apical dominance and encour-age branching.

A heading cut does two things. First, iteliminates the source o auxins (natural planthormones that inhibit branching) to the lateralshoot buds, encouraging multiple lateral breaks toarise immediately below the cut. These branchesincrease the number o leaves that produce carbo-hydrates or developing ruit lower on the branch.Oten, new shoot leaves are at least 50 percentlarger than spur leaves, thereby contributing sig-nicant photosynthetic potential.

The second important unction o a headingcut is to reduce the crop. A heading cut in 1-year-old wood reduces the uture cropping potentialo the branch. By removing one-third to one-hal

Figure 1. The owering spurs that will form at the base

of the previous seasons shoot growth will be spaced

farther apart, and will have fewer owers per spur,

than those that will form at the tip of that growth.

Step 1. Remove all pendant and small-diameter wood.

Step-by-step pruning for crop load management on productive rootstocks

o last years new growth rom every shoot dur-ing the dormant season, a substantial portion othe uture crop can be eliminated. In act, sinceterminal spurs produce more fowers than basalspurs and are closer together (Figure 1), removing

one-third o the new growth will reduce a branchsruiting potential by about one-hal.

Step 1. Thinning cuts

When: Dormant season, each yearHow: Remove pendant wood and weak shoots

less than pencil-size in diameter.Why: Removes wood that tends to overset and

produce small ruit.

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Step 4. Tip branches to reduce the future crop

and force production of large new leaves.

Step 2. Make stub cuts to reduce the current

seasons crop and force renewal of older

fruiting branches and spurs.

Step 3. Thin branches for light penetration.

tipped

branch

stub cut

Step 3. Thinning cuts

When: Dormant season, each yearHow: Thin new shoots to a single branch, espe-

cially at the top o the tree.Why: Allows light to penetrate the center and

bottom o the tree, maximizing photosynthesisand producing ruit throughout the canopy.

Step 4. Heading cuts

When: Beginning the rst dormant season, to berepeated each year

How: Tip all new uture ruiting branches,removing one-third to one-hal o every shoot.

Why: Encourages branching and creates newleaves. Reduces uture crop load by eliminatingthe buds that are closest together and will havethe most fowers per spur.

Step 2. Stub cuts

When: Dormant season, beginning ater the sec-ond year o signicant ruiting, to be repeatedevery year

How: Start renewing branches. Renew 20 percento all ruiting branches each year in order tokeep spurs young and producing high-qualityruit. Stub branches back, leaving 3- to 5-inchstubs at the top o the tree and longer stubs atthe bottom or where light intensity is less.

Why: Reduces current crop and renews spurs.

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2007 Oregon State University.

Published and distributed in furtherance of the Acts of Congress of May 8 and June 30, 1914, by the Oregon State University Extension Service,Washington State University Extension, University of Idaho Cooperative Extension System, and the U.S. Department of Agriculture cooperating. Thethree participating Extension Services offer educational programs, activities, and materialswithout regard to age, color, disability, gender identityor expression, marital status, national origin, race, religion, sex, sexual orientation, or veterans status. The Oregon State University Extension Service,

Washington State University Extension, and University of Idaho Extension are Equal Opportunity Employers.

Published January 2007. $4.00

A Spanish-language version o this publicationis also available (Cuatro pasos sencillos para lapoda de cerezos sobre Gisela y otros portainjertosproductivos, PNW 592-S). To view online or toorder printed copies, visit the OSU Extension Ser-

vice online Publications and Multimedia catalog(http://extension.oregonstate.edu/catalog/). Or,contact us by ax (541-737-0817), e-mail(puborders@oregonstate.edu), or phone (541-737-2513).

ReferencesWhiting, M.D. and G.A. Lang. 2004.

Bing sweet cherry on the dwarng rootstockGisela 5: Thinning aects ruit quality and veg-etative growth but not net CO2 exchange.J. Amer.

Soc. Hort. Sci. 129(3):407415.

A note about nitrogenBalancing the crop load to maintain the

proper LA:F ratio assumes that adequateirrigation and nutrient management are

practiced. In addition to soil-applied nitrogen(N), trees may benet rom a oliar spray olow-biuret (containing low levels o impuri-ties) urea (3045 lb N/acre). Apply oliarN in the all just prior to lea senescence.Choose a nitrogen product designed or oliarapplications to avoid burning the leaves. Thisapplication will increase N storage in the budsand might result in larger spur leaves in thespring (thus more carbohydrate productionor ruit growth). Some marginal lea burn

might occur at higher nitrogen spray rates, souse this oliar spray only on a trial basis at thistime.