GrowingKiwifruit

PNW 507 • Reprinted April 2005

A Pacific Northwest Extension publicationOregon State University • University of Idaho • Washington State University

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Contents

Bernadine Strik, Extension berrycrops professor, Department ofHorticulture, Oregon StateUniversity.

The technical assistance ofHelen Cahn and Gil Buller, NorthWillamette Research and Exten-sion Center, and ChantalakTiyayon and Marieles Pescie,graduate students, Oregon StateUniversity, is appreciated.

Introduction .......................................................................... 1

Kiwifruit Cultivars“Fuzzy” Kiwifruit ....................................................................... 3

Hardy Kiwi ................................................................................. 4

Kolomikta Kiwi .......................................................................... 6

Establishing Your Kiwifruit VineyardSite Selection and Preparation .................................................... 7

Vineyard Planning, Planting, and Spacing ................................. 8

Trellis ........................................................................................ 10

Irrigation ................................................................................... 11

Fertilization ............................................................................... 12

Training Young Vines ............................................................... 13

Maintaining Your Kiwifruit VineyardFertilization ............................................................................... 16

Irrigation ................................................................................... 17

Pollination ................................................................................. 17

Fruit Thinning ........................................................................... 18

Pruning and Training ................................................................ 18

Harvest, Handling, andStorage of Kiwifruit

Fruit Maturation ........................................................................ 21

Harvesting ................................................................................. 22

Storage ...................................................................................... 22

Pests .......................................................................................... 24

1

Kiwifruit arenative tosoutheast Asia.There are morethan 50 species in

the genus Actinidia, and manyhave commercial potential.

The most common kiwifruitspecies grown commercially isActinidia deliciosa cultivarHayward. Consumers are veryfamiliar with this brown, fuzzyfruit.

Hayward needs a growingseason of about 225 to 240 frost-free days. Although this speciesshould tolerate temperatures downto 10°F (–12°C), plants may bedamaged at slightly highertemperatures.

Actinidia chinensis, anotherlarge-fruited species, is growncommercially to a limited extent;this species offers yellow-fleshedcultivars. However, A. chinensis isnot quite cold-hardy enough forconsistent production in thePacific Northwest.

More hardy kiwifruit speciesalso are available. They includethe following:

• A. arguta, known as thehardy kiwi or arguta(marketed as “babykiwi” in Oregon and as“grape kiwi” in BritishColumbia)

• A. kolomikta, also known askolomikta or Arctic Beauty,which is cold hardy to –40°F(–40°C)

Young shoots and fruit of allkiwifruit species are very sensitiveto frost injury. Temperatures of30°F or less (–1°C) for only30 minutes can severely damageshoots in the spring and fruit inthe fall. Thus, in frost-sensitiveareas, kiwifruit can be grownsuccessfully only with overheadirrigation for frost protection (see“Irrigation”) or by using someother frost protection method (see“Site Selection”).

The kiwifruit is a dioeciousplant—it has separate male andfemale plants (with the exceptionof a few self-fertile cultivars). It isessential to plant male vines forpollination and crop production.

It is best to plant male andfemale vines of the same species.In general, 1 male is required forevery 6 to 10 females. Self-fertile cultivars require no malepollinizer, although fruit size maybe larger with cross-pollination.

The fruit of most commonkiwifruit species and cultivarshave green flesh that does notbrown when cut. Some commer-cial cultivars have yellow or redflesh.

Although some people claimthey eat the skin of fuzzy kiwi,

Introduction

2

most peel these fruit. However,the hardy and kolomikta kiwifruithave very edible skin. You canpop these delicious, small fruitsright into your mouth.

Kiwifruit are relatively high inacid, with the acid content reach-ing nearly 2 percent of freshweight at maturity and decliningafter harvest. Kiwifruit are one ofthe best natural sources of vitaminC, with a level at least twice thatof the orange.

Fuzzy kiwifruit can be storedfor months after harvest at 32 to35.5°F (0 to 2°C). However, thehardy kiwis can be stored for nomore than 2 months under thesame storage conditions. There-fore, you likely will see hardykiwifruit in stores up to only acouple of months after harvest(September through October)unless fruit are produced in thesouthern hemisphere and areshipped here.

Leaves of some kiwifruitspecies (A. kolomikta andA. polygama) contain a substancethat has an effect similar to catnip.In China, kiwivine leaves report-edly are fed to large cats as asedative. You may find that catsbecome a pest of your newkiwifruit planting! A. polygamamakes a nice ornamental vine. Thefruits are considered of lowerquality than those of other hardyspecies.

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Kiwifruit Cultivars

The informationbelow on ripeningdates, fruit weights,and plant perfor-mance is approxi-

mate and is for mature vines. It isbased on test results from acultivar planting at the OregonState University North WillametteResearch and Extension Center(NWREC), Aurora, Oregon.Performance may vary withlocation.

“Fuzzy” KiwifruitActinidia deliciosa, fuzzy

kiwifruit, is the most widelyavailable species. Fuzzy kiwi aregrown commercially in NewZealand, Italy, Japan, France,Australia, Greece, Chile, andCalifornia. There is some com-

mercial production inOregon and Wash-

ington (UnitedStates) and inBritish Columbia(Canada); however,this species is not

extremely hardy andmay suffer cold

injury in some years inthe Pacific Northwest.

Cold damage usuallyoccurs when temperatures

drop during the night after awarm spell, particularly when

vines are not fully dormant (in

fall or late winter). The trunkusually is damaged, which weak-ens older plants and sometimeskills young vines. Althoughmethods such as wraps and plasticsleeves may help protect the trunkagainst freeze injury, they are notalways effective. The trunk’ssensitivity to cold decreaseswith age.

Generally, fruit are large,with a green skin covered withbrown fuzz. Vitamin C contentranges from 100 to 200 mg per100 grams of fruit. The mostcommon commercial cultivar isHayward, which is found insupermarkets throughout theworld.

A yellow-fleshed fuzzy kiwi-fruit is now available in stores.This cultivar from New Zealand isHORT16A and is trademarked asZespri Gold. This cultivar belongsto the species A. chinensis. Noplants of this cultivar are presentlyavailable.

The following cultivars areavailable (all A. deliciosa) andhave been tested in the PacificNorthwest. All produce brightgreen-fleshed fruit. Ripening datesgiven below are based on whenfruit reached 6.5 °Brix (percentsugar) at the NWREC, a harvestdate criterion for long-termstorage (see “Harvest, Handling,and Storage of Kiwifruit”).

Kiwifruit Cultivars

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HaywardHayward is the most commonly

available cultivar found in stores.Its large, fuzzy, brown fruit withgood, sweet flavor has made itpopular. This cultivar is recom-mended only for areas of Oregonand Washington with mildwinters.

Harvest: mid- to late October,depending on summer heat units

Fruit weight: 80–90 gramsVine growth: vigorousYield: up to 100 lb/vine

Saanichton 12This cultivar comes from

Vancouver Island, British Colum-bia, where it has been grown formore than 30 years. Fruit arelarge, somewhat more rectangularthan Hayward, sweet, and of goodflavor. The inner core of the fruitcan be tough. It is reported to bemore winter cold hardy thanHayward.

Harvest: early OctoberFruit weight: 70–80 gramsVine growth: vigorous

BlakeA “self-fertile” cultivar

that does benefit from cross-pollination. Fruit are smaller thanHayward or Saanichton 12 and aremore oval in shape. Flavor isinferior to Hayward andSaanichton 12.

Harvest: early OctoberFruit weight: 60–70 gramsVine growth: vigorous

Male (A. deliciosa)A pollinizer is required for all

fuzzy kiwi, with the possibleexception of Blake. There aremany cultivars/selections of malesavailable. Examples include

Matua, Tomuri, Cal Chico No. 3,Chico Early, and Chico ExtraEarly. Males of these cultivarshave not been tested for differ-ences in performance in thePacific Northwest.

Hardy KiwiThe hardy kiwifruit species

most recommended for productionin the Pacific Northwest isA. arguta. In 2000, there were anestimated 100 acres of A. argutacultivar Ananasnaya in the PacificNorthwest. Very few cultivars ofthis species are grown here.

Hardy kiwi plants are veryvigorous and produce a good-quality, highly aromatic fruit thatis quite different from the fruit ofA. deliciosa. Fruit are smoothskinned (skin can be eaten),generally green in color, and muchsmaller than the fuzzy types. Theflavor is excellent, but it varies bycultivar. Vitamin C content isvery good at 10 to 70 mg per100 grams of fresh fruit. Hardykiwifruit are well suited to thehome garden.

A. arguta is grown commer-cially in the United States,Canada, New Zealand, Chile, andparts of Europe. Oregon, with anestimated 100 acres of the cultivarAnanasnaya in production in2000, is the world’s largestproduction region.

Commercial acreage has beenlimited mainly by marketingfactors, such as development offresh markets for this relativelyunusual fruit, the range in fruitsize, the limited ripening period,and the relatively short storageand shelf life compared tofuzzy kiwifruit. The continued

development of processed marketslikely will strengthen this industry.As markets are developed, youwill see and hear more about thesetypes, as they do have good-quality, attractive fruit.

A. arguta is hardy to –10 to–25°F (–23 to –32°C) under mostconditions. Damage to the trunkfrom cold temperatures rarelyoccurs in Oregon or Washington.Keep in mind that young vinesmay be more cold sensitive.Protect them with trunk wraps(see “Establishing Your KiwifruitVineyard”).

Maximum hardiness levelsgiven for this species reflect onlymidwinter hardiness. This specieshas a low chilling requirement(winter rest period satisfied bytemperatures at 32 to 45°F) andmay be sensitive to cold injury athigher temperatures when warmweather precedes a cold spell,particularly in late winter.

Unfortunately, warm tempera-tures in February or March maypromote early bud break, makingthis species very susceptible tofrost damage of the young shoots.Therefore, this species cannot begrown commercially in most areaswithout frost protection whentemperatures drop below 32°Fafter bud break (also see “Siteselection”). In Oregon and mostareas of Washington, frost protec-tion is required in the late winter/early spring after bud breakoccurs. However, trial plants atWashington State University-Mt. Vernon have grown wellwithout frost protection—prob-ably due to the marine influenceof the Puget Sound.

Production requirements forthis crop are a well-drained soil

5

Kiwifruit Cultivars

with a neutral pH, no history ofphytophthora root rot or presenceof nematodes, and a source ofgood irrigation water.

Fruit of hardy kiwi are bestwhen ripened on the vine tomaximize development of aromaand flavor; however, shelf lifethen is shortened. Harvest datesgiven below are based on sugarlevels of 10 to 14 °Brix. (If lefton the vine, the fruit will reach18 to 25 °Brix.)

AnanasnayaThis is the most popular hardy

kiwifruit cultivar currently avail-able. Its Russian name means“pineapplelike.” You also mayhear this cultivar referred to as“Anna.”

Fruit are of very good quality,with a good aroma and sweet,intense flavor. They have greenskin that develops a purple-redblush in full sun, especially whenvine ripened. Skin may be slightlytough.

The cultivar Ananasnayabrought to Oregon is A. arguta.However, the Russian Ananasnayacultivar is A. kolomikta; more thanone cultivar with the same namemay be available in nurseries.

Harvest: mid- to late SeptemberYield: 60–150 lb/vineFruit weight: 6–14 gramsVine growth: very vigorous

Issai (self-fertile)This cultivar from Japan is less

vigorous than the other hardykiwifruit cultivars listed above.Fruit are smaller in size,

somewhat cylindrical, come to apoint, and are fully green. Flavorand aroma are very good. Harvest-ing is somewhat more difficultthan for the other hardy kiwi,because fruit are smaller and ripenrather unevenly within a cluster.This cultivar, although self-fertile,produces larger fruit with seedswhen cross-pollinated. Vines areslightly less hardy than otherA. arguta at 0 to –10°F (–18 to–23°C).

Harvest: early SeptemberYield: 50–90 lb/vineFruit weight: 4–9 gramsVine growth: moderate vigor

74-49This numbered selection came

from a USDA program in Chico,California. This selectionproduces very good-quality fruitof similar size and quality toAnanasnaya.

Harvest: early to mid- September

Yield: 60–125 lb/vineFruit weight: 6–12 gramsVine growth: very vigorous

JumboNot yet widely tested in the

Pacific Northwest. The green fruitare reputed to be of good flavor,larger than those of Ananasnayaand ripening in late September.

A. arguta var. cordifoliaNot yet widely tested in the

Pacific Northwest. The green fruithave a good flavor and are verysweet. Plants are very vigorousand produce high yields. Flowersmay be wind pollinated.

A. purpureaA red-skinned, red-fleshed

hardy kiwifruit. This species hasnot yet undergone extensivetesting in the Pacific Northwest.Fruit generally are smaller thanthose of Ananasnaya and ripen inearly October. Flavor is good.

Ken’s RedNot widely tested in the Pacific

Northwest, this kiwifruit fromNew Zealand is a cross ofA. arguta var. cordifolia andA. melanandra. Fruit are nearlysquare to cylindrical with a “nib”at the tip. They are bright green insummer, and skin turns red late inthe season. Flesh is reddishpurple when ripe. Vines are veryvigorous.

MalePollinizer for above A. arguta

species. About one male is neededfor every eight females. There isevidence that A. arguta cultivarscan be pollinated by A. deliciosamales, which produce more pollenthan arguta males. However,A. deliciosa males are much lesshardy than A. arguta males;thus, you risk crop loss to coldinjury when using fuzzy males(see “Pollination” for moreinformation).

Other cultivars/selections thatmay be available includeDumbarton Oaks, 74-45, 74-8,and Michigan (reported to havealmost twice the fruit size ofAnanasnaya). These cultivars havenot been widely tested in Oregon.

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Kolomikta KiwiThese kiwi types, A. kolomikta,

are hardy to –40°F (–40°C), butshoots are sensitive to frostdamage. In the Willamette Valley,Oregon, A. kolomikta cultivarshave been found to break budearlier than arguta types in latewinter, making them moresensitive to frost. Availablecultivars differ greatly in fruitshape, size, color, and flavor. Fruitof kolomikta are smaller thanthose of arguta kiwivines. Plantsare considered good ornamentalsbecause of their variegated pinkleaves, particularly in the male.

The fruit are small to medium-size, but very sweet, with goodaroma and flavor. Fruit are valuedfor their exceptionally high

vitamin C content—700 to1,000 mg/100 grams of fruit(10 times higher than Haywardand 20 times higher than citrus).

Fruit are best when ripened onthe vine to maximize aroma andflavor development; however,shelf life then is shortened.

This species has not performedwell in test plantings at theNWREC, Aurora, Oregon, or inBritish Columbia, Canada.A. kolomikta seems more sensitivethan other species to wet soils orphyophthora root rot and does notgrow well in full sun based onfindings at the NWREC.A. kolomikta is not grown com-mercially in the PacificNorthwest.

Nevertheless, the followingcultivars may perform well at

other sites and certainly wouldmake good ornamental fruit plantsin the home garden.

KrupnopladnayaThis cultivar, “large fruit” in

Russian, is the largest of the arcticbeauties tested in Oregon. Flavoris good and sweet. Plants havelow to moderate vigor comparedto A. deliciosa.

PautskeThis is the most vigorous of the

arctic beauties tested in Oregon.Fruit are large and of good quality.Plants are more vigorous thanthose of Krupnopladnaya, but stillhave lower vigor than A. deliciosa.

MaleAn A. kolomikta male is needed

to pollenize the above cultivars.

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Establishing YourKiwifruit Vineyard

Vine growth andfruiting habit ofboth fuzzy andhardy kiwifruitare similar. The

following information on vineyardestablishment applies to all of theaforementioned species unlessdifferences are noted.

Site Selection andPreparation

Proper site selection, soilpreparation, irrigation systemdesign, planting design, andtraining are essential to develop-ing a productive kiwifruitvineyard.

Site selectionThe single most limiting factor

for fuzzy kiwifruit production istemperature. A. deliciosa Haywardcan withstand temperatures as lowas 10°F (–12°C). Cold injury toHayward has occurred in somewinters in the Pacific Northwest.

Dormant A. arguta vines aremuch more cold-hardy than thefuzzy types (to –10 to –25°F or–23 to –32°C). However, youngvines of this species also cansuffer winter injury, particularly tothe trunk, if temperatures fluctuatefrom warm to cold in late winter.Both A. arguta and A. deliciosavines are sensitive to late winter orspring frost damage after budbreak.

Male vines are less hardy thanfemale vines (documented inOregon).

There are several ways to helpprevent freeze and frost injury:

• Do not plant in low areas orcool sites.

• Remove barriers (e.g., trees) tocold air drainage.

• Keep in mind that clean,cultivated sites are warmerduring frost periods than siteswith permanent cover crops.

• Do not cultivate immediatelyprior to a projected frost,because cultivation reducesheat transfer from soil to air atnight.

• For protection from frostdamage using irrigation afterbud break, see “Irrigation.”

• Wind machines or heatingdevices such as smudge potscan prevent frost damageduring temperature inversions(warm air is above the colderair).

• In the home garden, you canuse spunbound row covers tooffer some protection. Placecovers over plants before sunsetand remove when temperaturesrise above freezing.

Chemicals that reduce vinetranspiration (antidesiccants) havenot been shown to reduce frostinjury in kiwifruit.

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Table 1.—Guidelines for irrigation water quality.

Chloride < 70 ppmBicarbonate < 200 ppmBoron < 0.25 ppmSodium < 50 ppmElectrical conductivity, EC x 10 < 0.75

Wind damageLong shoots are very suscep-

tible to wind damage or breakagein spring and summer. Not onlycan wind cause fruit loss, but italso may reduce economic yieldsby causing the fruit to rub. Whenrubbed, fuzzy kiwi first lose theirfuzz and then develop a callus,whereas the hardy types developa callused or scabbed area.Scabbed fruit are suitable only forprocessing.

In windy areas, wind breakssuch as poplars help reduceeconomic losses. Plant windbreaks to provide 200 to 250 feetof protection downwind. Makesure wind breaks are not plantedclose enough to the vineyard rowsto reduce yield of the kiwifruitthrough competition for light andwater.

SoilThe optimum pH for Hayward

is between 5.5 and 6.0. Vinesshow poor growth at a pH above7.2. It is not known whether otherspecies differ in pH requirements.However, A. arguta has performedwell in Oregon at the same pHrange.

Kiwivines do best in deep,well-drained soils. They are verysensitive to standing water,especially after bud break inspring. Research in New Zealandhas shown that if roots are water-logged for 3 days or more, the rootsystem and vine growth areseverely damaged.

In California, it is recom-mended that kiwifruit be plantedon 3 feet of well-drained soil.However, Hayward vines havegrown well on soils with an

effective rooting depth of 2 feet,provided the water table is lowerthan 2 feet.

Install well-designed drain tilesto improve drainage if necessary.Ripping the soil below the rowbefore planting also can benefitgrowth.

In the Pacific Northwest, werecommend planting vines onraised beds (at least 1 foot high).This method reduces risk of vinedeath from phytophthora root rot.Young and mature vines ofA. deliciosa and A. arguta havebeen killed by phytophthora whengrown on “flat ground” in Oregon.

Do not pile soil around the baseof the trunk of established kiwi-fruit vines with the objective offorming a “raised bed” afterplanting. Doing so can kill vines.

Previous cropping historyKiwifruit are susceptible to

verticillium wilt. Avoid planting insoils with a history of strawberry,black raspberry, potatoes, or othercrops in the Solanaceae family.

Plants also are sensitive to rootknot nematodes (Meloidogynespp.). Although the literature onnematodes relates to Hayward, it’sbest to assume that A. arguta issimilarly sensitive. Kiwifruit alsoare susceptible to Armillaria oakroot fungus, which may be presenton sites where oak trees havegrown.

A preplant soil test for nema-todes is recommended. Ifnematodes or oak root fungus arepresent, use a preplant fumigant.

Young kiwifruit vines competepoorly with weeds, so eliminate asmany perennial weeds as possiblebefore planting. A permanentcover crop or a natural weed stripmay be maintained between rows.

WaterA plentiful supply of good-

quality water is required forkiwifruit production. Plants need40 to 48 acre-inches of water peryear. Expect to apply about2 inches of water for each inch ofwater needed. Table 1 showsguidelines for irrigation waterquality that are considered safe inCalifornia.

Vineyard Planning,Planting, andSpacing

We estimate that it costs morethan $12,000 per acre, not includ-ing land cost, to establish akiwifruit vineyard and bring it toproduction. It takes 3 or moreyears after planting to produce acommercial crop.

Planting designPresently, the common training

system used for kiwifruit vine-yards in the Pacific Northwest is a

9

pergola (solid overhead canopy).However, a T-bar system hasyielded well at the NWREC, iseasier to prune, and may be bettersuited for small-scale production.

For a T-bar trellis, vines com-monly are planted 15 feet apart inrows 15 feet apart, resulting in194 plants per acre. With a ratio of1 male: 8 females, there are 174female vines per acre. For thepergola, you may want to spacerows 15 to 20 feet apart (see“Trellis”).

Kiwifruit vines are extremelyvigorous. Canes grow 6 to 12 feetper year, and occasionally 20 feet.Higher density plantings mayincrease production in the earlyyears, but in later years, over-growth and shading will requireexcessive summer pruning.

The kiwifruit is a dioeciousplant—it has separate male andfemale plants (with the exceptionof a few self-fertile cultivars).Male vines are essential forpollination and crop production.In general, plant the same speciesof male as the female vines (see“Pollination”) and about one malefor every eight female plants.Male and female vines must bepresent in a block and must flowerat the same time.

You can achieve a 1:8 male–female ratio with the followingdesign:

• Plant only female plants in alloutside rows.

• Plant the following row with amale plant between every twofemale plants.

• Plant the next two rows with allfemale plants.

• Plant another row with a maleplant between every twofemales.

• Plant two more rows of allfemale plants.

• Continue as above.

Male plants in these plantingsystems run at right angles to therows. For T-bar systems, you maywant to place males in every row,as there is some evidence that beesprefer to work down rows ratherthan across.

PlantingSelf-rooted vines perform

better than grafted vines in theNorthwest’s cold winters.Although grafted kiwifruit areavailable from many nurseries,planting kiwifruit on their ownroots in areas where cold injurymay occur is recommended.Severe cold spells can kill agrafted vine past the graft union,thus killing the vine. On cold-injured, self-rooted vines, suckerscan be trained up from below thewinter-killed portion.

Using rootstocks in kiwifruitproduction could offer manyadvantages:

• Vigor reduction

• Greater tolerance for adversesoil conditions such as waterlogging

• Greater physiological coldtolerance

• Resistance to pests or diseases

• More precocious and higher-yielding vines

However, research is needed onrootstock possibilities in kiwifruit.

Plant 2-year-old bare-rootor container stock. Purchase

bare-root nursery stock as close toplanting time as possible. Don’tallow the roots to dry out. Plant asearly in the spring as possible.Container-grown plants can beplanted at any time except mid-summer.

Plant on raised beds to reducethe risk of phytophthora. Carefullymark your field prior to planting.Planting all of the males first andthen filling in with females isrecommended.

Install your irrigation systembefore planting (see “Irrigation”).Establish your trellis prior to, orjust after, planting (see “Trellis”).Place the row posts betweenplants so that if post repair isneeded, the vine trunk will not bein the way.

Make the planting hole largeenough to accommodate the rootswithout bending them. You maytrim the roots a little to make themfit the hole. Do not dig the holedeeper than needed. Do not addany fertilizers, including manures,to the planting hole, as the rootsare very sensitive to fertilizerburn. Incorporate soil amendmentsthe fall prior to planting.

Plant vines just deeply enoughto cover the top roots. Nevermound soil around the plant, evenwhen the plant is established.Keep the soil moist enough topromote root growth, but don’toverwater, which can causeanaerobic conditions that promoteroot rots.

You can paint the trunks with amixture of 1:1 water and interiorwhite latex paint to help preventsunburn. Milk cartons also canprotect against sunburn and rodentfeeding. Place a trunk wrap

Establishing Your Kiwifruit Vineyard

10

around all species of kiwifruitvines in winter, except forA. arguta older than 5 years.“Grow tubes” can be used onyoung plants throughout thegrowing season. However, inwarmer areas damage hasoccurred to the young trunk wherethe top of the grow tube ends.

TrellisKiwifruit vines are not self-

supporting; their size, vigor,longevity, and heavy crop loadmean they need a strong, perma-nent support structure.

Two main types of supportstructures or trellises are used incommercial kiwifruit production:the T-bar and the pergola. Apergola provides a single plane ofcanopy about 6 feet above theground. The T-bar trellis systemconsists of posts in rows with across arm at 6 feet high.

T-bars are less expensive toconstruct, make pruning lesslabor-intensive, and are bettersuited to bee pollination. Once thefull canopy is established in apergola, the shade reduces weedgrowth. However, if the canopy ona pergola is too dense, fruit qualitymay be reduced as a result ofpremature softening.

T-barA typical T-bar trellis consists

of posts with a 5- to 6-foot-longcross arm (depending on rowwidth) extending across each post(Figure 1-A). The kiwivinefruiting canes are tied to wires ontop of the cross arm.

Use pressure-treated 4- to6-inch diameter posts that are 8 to9 feet long spaced at 15 to 20 feet

down the row. Square posts areeasier to work with. Drive posts 2to 3 feet into the ground. Use endposts that are at least 6 inches indiameter, and drive them at anangle with the top of the postleaning 1 foot from perpendicularaway from the row. Anchor theend posts well.

The top of the cross arm is6 feet above the ground. Crossarms usually are a 2- x 6-inchboard bolted into a cut notch onthe post. You can brace cross armsback to the post for addedstrength.

Run a wire down the row fromthe top middle and each side of

wires

6'

5–6'

Figure 1-A.—Standard T-bar trellis system for kiwifruit.

wires

Figure 1-B.—Winged T-bar trellis system for kiwifruit.

45° angle

5–6'

6'

11

the cross arms (Figure 1-A). Twoadditional wires can be added, onebetween the center and each endwire. Use galvanized, high-tensile,12-gauge wire for the vine sup-ports. Good wire tighteners areneeded to keep a strong tension onthe wires to support the vines andcrop.

A common modification of theT-bar is the winged T-bar, inwhich an additional wing and wireare added to each side of the T-barcross arm (Figure 1-B). Tyingdown a cane from the center wireonto the two wires pulls it into amore natural curve.

PergolaA pergola trellis is designed to

support a solid canopy of foliageand fruit (Figure 2). Wires notonly extend down the row, butalso are used as “cross arms”(more commonly than usingwood) running perpendicular tothe vine rows. The wires areplaced 1 to 3 feet apart.

IrrigationGood irrigation is critical for

good growth and production.Irrigate young plants enough towet the root zone without keepingthe crown too wet; otherwise,crown or root rot may occur. Inyoung plants, the range betweentoo wet and too dry is narrow.

Unfortunately, there is rela-tively little direct experience onwater requirements of hardykiwifruit in the Pacific Northwest.The following information relatesto Hayward production and ourobservations with A. arguta herein the Pacific Northwest.

Growers often irrigate byexperience rather than irrigationscheduling tools. In kiwifruit,however, observing vines fortrouble signs doesn’t work well,because by the time water stresssymptoms are visible, damage hasoccurred.

Vines under mild or moderatewater stress have a subtle off-color

look, with the foliage turningblue-green. Other symptomsinclude poor shoot growth,wilting, small fruit, sunburn, andreduced yield in the current andfollowing season. In situations ofsevere water stress, vine leaveswill turn yellow.

There are various types ofirrigation systems. Unfortunately,there is no single best system.Design a system that can supplyup to 35 gallons of water permature vine per day during thegrowing season. Irrigate vinesonce or twice per week. Surfacemulch may help conserve soilmoisture.

Drip systemsDrip systems economize on

water use, but on lighter soilsoften supply water to only anarrow cone of soil. Frequentirrigations are necessary, particu-larly to young plants with smallroot systems. However, as thecrown tends to stay drier, risk ofcrown rot (phytophthora) may bereduced. You can’t use dripsystems for frost protection.

Drip irrigation systems com-monly are used in California inyoung plantings. At planting, oneemitter is placed near each plant.The second year, two emitters areplaced 12 to 18 inches from thetrunk, and the one near the trunk isremoved (to keep the trunkrelatively dry). When the plant is4 years old, two more emitters areadded 3 feet away from the trunk.

When plants are mature,California growers find it difficultto supply enough water with fouremitters per vine, so they addmore emitters or switch tominisprinklers. For larger vines, asFigure 2.—Pergola trellis system for kiwifruit.

horizontal stayassembly

tie-back assembly

6'

6'

6'

20'

10'

Establishing Your Kiwifruit Vineyard

12

many as 10 emitters per vine maybe necessary.

Minisprinkler systemsUnder-vine minisprinkler

systems, which produce a wettedarea of greater size, often arepreferred over drip systems. Ingeneral, they wet more soil thandrip emitters do, are easy toinstall, and tend to plug lessfrequently than drip emitters.They can be used to replacedrip systems as vineyards age.In young vineyards, however,minisprinklers tend tooverirrigate.

These sprinklers spray water ina 6- to 18-foot diameter circle.One full-turn minisprinkler pervine, located equidistant betweenvines, should be adequate inmature plantings. Generally, theyare run 6 to 12 hours, two to fourtimes per week.

Impact sprinklersImpact sprinklers are the most

common type of irrigation systemused in kiwifruit vineyards in thePacific Northwest. They can beplaced over or under the canopy.Impact systems work well if thecanopies aren’t in the way, butthey tend to use more water thandrip or minisprinkler systems.

Overhead sprinklers are best forfrost protection. Some growersuse a T assembly on the sprinklerriser to switch from over-vinesprinklers to under-vine sprin-klers. They use the over-vinepositions for frost protection(shoots in the spring, fruit in thefall) and switch to the under-vineposition in summer. (Note thatonly fuzzy kiwifruit are sensitive

to fall frosts, because hardykiwifruit mature earlier.)

Place under-vine sprinklersbetween vines in order to reduceimpact on the trunk.

Frost protectionAll kiwifruit species are

sensitive to frost damage in thePacific Northwest. After chillingis satisfied and temperatures warmup in late winter or spring, budswill break. Only one shoot isproduced per node. If that shoot isdamaged by frost, no crop will beproduced at that node. We haveobserved total crop loss after budbreak at temperatures below 32ºFwithout frost protection.

Over-canopy sprinklers canprovide 6 to 8°F frost protection,whereas under-vine impactsprinklers can provide about 2 to3°F protection. Typically, 5/16-inchsprinklers are used at a spacing of30 x 40 feet (at 50 lb/inch pres-sure) to supply 0.1 inch/hour(50 gallons/acre/minute). Startsprinkler irrigation before tem-peratures fall below the criticallevel (31 to 32°F), and continueuntil temperatures are abovecritical levels and ice melts.

FertilizationIt is relatively easy to burn the

roots of kiwivines, so applyfertilizer cautiously. The followingrecommendations are based on ourexperiences in the PacificNorthwest.

Fertilize young kiwifruit vinesmonthly with small amounts ofnitrogen (N). Ammonium nitrateand urea are good sources ofnitrogen for kiwifruit.

In the first year, apply no morethan 0.4 oz of actual N per plantper month in May, June, and July(12 lb actual N per acre for 160plants per acre). Spread thenitrogen in a circle 6 to 12 inchesfrom the base of the trunk.

In the year after planting, apply0.8 oz of N per plant per month inApril, May, June, and July (32 lbN per acre). Spread the fertilizer ina ring about 12 to 36 inches fromthe trunk.

Fertilize third- and fourth-yearplants with 2 to 3 oz of actual Nevery other month from Marchthrough July (60 to 90 lb N peracre). Apply the fertilizer as abroadcast band under the vinecanopy. You may liquid-feednitrogen to young plants on a2-week to monthly interval insteadof using granular fertilizer.

Do not fertilize young plantswith liquid or granular forms ofnitrogen later than July. Latefertilization forces late vegetativegrowth, which is very sensitive tocold injury. Once plants bear fruit,the crop load tends to suppresslate vegetative growth and reducethe risk of fall frost damage.

Other nutrients may be added inspring either foliarly or to the soilsurface. Base applications onnutrient needs/analysis. Kiwifruitvines tend to take up a consider-able amount of phosphorus (P)and potassium (K). Test soil for Pand K prior to planting, andincorporate nutrients preplant ifnecessary.

DO NOT use fertilizer con-taining chloride (i.e., KCl), askiwivines are very sensitive tochloride.

13

Training YoungVines

Proper pruning during theestablishment years is necessary toestablish a well-formed permanentframework for the vine. Develop-ing or training young kiwifruitvines into a bilateral cordonallows for easier managementwhen the plants are mature.Kiwifruit produce a crop onshoots that grow from 1-year-oldcanes (last year’s growth). In thefirst few years, you train vines thesame way for both the pergola andthe T-bar system.

Prune dormant kiwivines in lateDecember to late January in thePacific Northwest. Later pruningmay cause excessive sap flow.

First growing seasonThe main objective during the

planting year is to develop asingle, straight trunk. At planting,prune plants back to one or twobuds (above the graft union ingrafted plants) (Figure 3-A,page 14).

Once shoots start to grow,select one vigorous shoot to trainupward as the trunk. Place a stakebeside the shoot to facilitatetraining. String from the wire tothe stake can add support as well.Tie the shoot to the stake (not tootightly or you’ll girdle the shoot)at frequent intervals to helpprevent breakage (Figure 3-B).

Do not allow the shoot to wraparound the stake. Concentrategrowth into this shoot by remov-ing suckers at the base of the vine.

Remove all basal lateral shootsthat break along the trunk. If themain shoot loses vigor and begins

to twist slightly, top the shoot andtrain up the strong new “leader”(Figure 3-C). Continue to train thetrunk until it’s 2 to 3 inches abovethe wire (Figure 3-D).

If the shoot reaches the wireearly in the season, you may try toform the cordons in the first year.To do so, top the shoot to about4 inches below the training wire toencourage lateral branch forma-tion. This forms a nice “Y” for thecordons. Select two shoots,growing in opposite directions,and train them along the centerwire to form the two main arms,called cordons (Figure 3-E).

Another option is to train thetrunk up one way along the wireand wait until the next season totrain a shoot the other way. Thisresults in cordons of unequal age,which may make management alittle more difficult in the short-term.

During the first dormantseason, head back the cordon(s) towood of 1/4 inch in diameter orlarger (Figure 3-E). If vines didnot have adequate growth to formcordons the first season, head thetrunk back about 2 inches belowthe trellis wire to force new budsearly the next season.

Second seasonThe objective in this season is

to develop two permanent cordonsfrom two strong shoots growing inopposite directions from the trunkalong the center wire. If cordonswere established in the plantingyear, there will be a light cropproduced in year two. As eachcordon grows, lay the shoot atopthe wire and tie it every 18 to24 inches with tie tape to ensure

that it’s securely attached to thewire. If only a trunk was estab-lished in the planting year, traintwo shoots near the top of thetrunk, just under the wire, tobecome the cordons. Remove allother shoots and any suckersthroughout the season.

Retain shoots that are producedalong the cordons at about 8- to12-inch intervals. Carefully tiethese shoots to the outer trelliswires. Remove all other shoots bysummer pruning before they twistaround the shoots you want tokeep. Remove unwanted suckersand shoots throughout the season.

In the dormant season, prunethe main cordons and the retainedlateral canes back to wood 1/4 inchin diameter or larger (Figure 3-F).A crop will form on shoots fromthese canes in the third year.Pruning the canes during thedormant season encouragesfruiting the following year.

Third seasonContinue to extend the cordons,

if necessary, by training thestrongest shoots down the centerwire until they’re within about1 foot of the cordon of adjacentvines. Do not allow them to twisttightly around the wire, whichmight restrict sap flow later.

Continue to train lateralbranches perpendicular to thecordons (Figure 4, page 15). Donot train shoots along the outerwires parallel to the cordon; theywould cause too much competi-tion for light.

In the third dormant period,prune so that 15 to 20 well-spacedlateral canes remain on the vine,depending on vigor. Fruit will

Establishing Your Kiwifruit Vineyard

14

center wire

center wire

(A) (B) (C) (D)

(E) (F)

Figure 3.—Training a young kiwifruit vine. Pruning cuts are shown by .(A) Prune to one or two buds at planting.(B) Train one shoot as trunk; remove all others (Year 1).(C) Head back trunk as shoot growth at terminal loses vigor.(D) Continue to remove lateral shoots; let trunk grow beyond wire. Then head to just below wire.(E) Choose two shoots to form cordons, one each way on wire. Head back to 1⁄4-inch-diameter wood in dormant season

(Year 1).(F) Shows shoot growth Year 2. Pruning cuts in dormant season Year 2 are shown.

15

form on shoots produced on lastyear’s growth (Figure 4). Do notovercrop (allow a young vine toproduce too much fruit).Overcropping will lead to highyield, but small fruit size, reducedvegetative growth, and a reducedcrop the following year. Reducecrop by leaving fewer buds or1-year-old fruiting canes. Removeany suckers or side growth on thetrunk. Concentrate on developingor finishing the vine’s framework.Fruit in the third year may sun-burn due to inadequate canopycover. It may be a good idea to

remove some of the fruit early inthe season to divert more energyinto vegetative growth.

The permanent vine structureshould be established by the thirdor fourth year. Future pruning willrenew fruiting canes and maintainthe vine framework and crop load.See “Maintaining Your KiwifruitVineyard” for diagrams/descrip-tions of pruning mature vines.

Training of vines to a T-bar andpergola system is similar. In apergola, the vines are grown asstraight, single trunks until theyreach the top of the structure. Onestrong permanent leader (cordon)

then is allowed to grow in eachdirection along the main wire.

To form the canopy of apergola, develop a system offruiting canes from the cordons atright angles to the wires. Fruitingcanes can be retained longer onpergolas and may be more perma-nent than on T-bars. Fruitinglaterals or shoots develop on thefruiting canes. It takes up to7 years to develop a full canopy ina pergola. Note that it is easier toleave too many fruiting buds on apergola, thus reducing fruit sizethe following season.

center wire

wires

wires

Figure 4.—Kiwifruit vine in third growing season during fruiting. Leaves not shown on right to simplify drawing.

Establishing Your Kiwifruit Vineyard

16

Maintaining YourKiwifruit Vineyard

It is essential to maintainyour kiwifruit vineyardwell for optimumgrowth and productivity.Pruning probably is the

most challenging aspect ofvineyard maintenance.

At Oregon State University, wehave conducted several experi-ments on the fruiting and pruningof hardy kiwifruit. Our findingsare incorporated into this chapter.

FertilizationIt is relatively easy to burn the

roots of kiwivines, so applyfertilizer cautiously. When apply-ing granular N, be sure to broad-cast it over the entire root zonearea; concentrating it near thetrunk can burn roots. Leaf necrosisor blackening of the leaf edges is asymptom of fertilizer burn.

Mature vines (7 years andolder) use about 1 lb of actualnitrogen per vine per year, orabout 190 lb N per acre per year(with 15 x 15 foot spacing).

Apply about two-thirds of thenitrogen in March at bud break asa broadcast application under thecanopy. This provides the nitrogenneeded for early-season growthand fruit set in June. A secondapplication of granular N, theremaining one-third, is recom-mended in May–June.

Plants should have good soilmoisture when they are fertilized.Irrigate first, wait 1 or 2 days, thenfertilize; or fertilize after a goodrainfall.

You can substitute liquidfertilizer applied through theirrigation system for dry fertilizer.When applying liquid fertilizerscontaining N, use about 10 lb ofactual N in each application fromApril through July. Higher rates ofliquid N (20 lb per application)have injured roots on lighter soils.

Base fertilization with othernutrients on tissue and soil analy-sis. Critical levels for leaf samplestaken in late August in Californiaand for New Zealand are given inTable 2 (recommendations from

Table 2.—Kiwifruit leaf sufficiency levels for nutrients.

Nutrient % dry weight Nutrient ppm

Calcium 2.0–4.0 Boron 25–200Magnesium 0.2–0.8 Copper 5–15Nitrogen 2.0–2.8 Iron 60–200Phosphorus 0.13–0.3 Manganese 50–200Potassium 1.5–2.5 Zinc 15–30Sulfur 0.15–0.45

17

both areas are combined). It is notknown whether species differ innutrient needs or whether criticallevels vary by region. However,these values can be used as aguide.

Based on experience in NewZealand and California, growerstypically apply the following as amaintenance application:

• 55 lb phosphorus per acre inFebruary–March

• 80 to 130 lb potassium per acreas a single application in latewinter/early spring or split,depending on soil type

Maintain soil pH at about 6.0with lime application in the fall.

Kiwifruit are very sensitive tochlorine, so do not use anyfertilizers with chloride.

IrrigationThe water a vine loses through

transpiration must be replaced byirrigation or rainfall. Transpirationoccurs when leaves use carbondioxide to produce carbohydratesthrough photosynthesis. On awarm summer day in California,mature, full-canopy kiwifruitvines can transpire 7,000 to8,000 gallons of water per acreper day.

Irrigation is necessary to keepvines growing and productive andto maximize fruit size. Waterstress can reduce fruit size, limitflower numbers (by reducingflower bud initiation), and causepremature fruit drop. Summerdrought can cause leaf drop andpremature fruit ripening inA. arguta; however, fruit ripen

more unevenly and are of poorerflavor. Severe drought also maycause fall flowering, whichreduces the following year’sproduction. Maturity of wood alsoseems to be delayed by drought,thus increasing risk of cold injury.However, too much water alsomay cause production problems.

Judging vine water needs isdifficult. At this time, it’s notknown whether irrigation require-ments in the Pacific Northwestdiffer from those in other regions.Based on information from BritishColumbia, Canada, vine water useranges from 25 to 35 gallons pervine per day (at 70 to 80°F).

Irrigation for frost protectionalso is necessary to protect youngshoots in spring and potentiallyfruit in fall (for fuzzy kiwifruitonly). See “Establishing YourKiwifruit Vineyard” for moreinformation.

PollinationFor fruit to be produced, male

and female vines must be presentin a block and must flower at thesame time. Male flowers produceviable pollen for only the first2 to 3 days after opening. How-ever, female flowers are receptiveto pollen for 7 to 9 days afteropening, even when the petalshave started falling.

Pollination is extremely impor-tant in kiwifruit production. LargeHayward fruit contain 1,000 to1,400 seeds, and Ananasnaya fruitcontain up to 240 seeds. If pollina-tion is poor, fruit will haveindentations (narrow valleys) on

one side or be nonuniform inshape. If you cut through thesefruit, you’ll find no seeds in theseareas.

Hardy kiwifruit vines, evenwhen well pruned, can have10,000 flowers per vine.

Kiwifruit flowers are pollinatedmainly by insects, although windmay play a minor role. Honeybeesare the main pollinator used inkiwifruit vineyards.

Kiwifruit flowers do notproduce nectar and are relativelyunattractive to bees. About threeto four hives per acre are neededto adequately pollinate kiwifruit.Place hives in the vineyard nosooner than 10 percent bloom ofthe female vines.

In some years, you may haveno male vines in flower as a resultof cold injury to male plants inlate winter or early spring (theyare less hardy than the females).In this case, no naturally producedpollen will be available. To get acrop, the females will have to bepollinated artificially. There arepresently no sources of A. argutapollen. Fortunately, A. deliciosapollen will work well forA. arguta females. Pollen is sent ina pure form with about 20 millionpollen grains per gram. To provideartificial pollination, you mustapply 10 grams per acre per daystarting at about 10 percent bloomof the female vines. You can applypollen with a special “dry”applicator or in a solution. Callyour county Extension faculty formore information on sources ofpollen and methods of artificialpollination.

Maintaining Your Kiwifruit Vineyard

18

Fruit ThinningFruit thinning, or removing

fruit after set, can be done toremove misshapen fruit that areunmarketable and to increase thesize of the remaining fruit. How-ever, after studying fruit thinningin hardy kiwifruit, it is doubtfulwhether thinning is economical.Proper dormant-season pruningbalances the crop load and cangreatly affect fruit size. Leavingtoo many buds after pruning willdecrease fruit size.

Pruning and TrainingProper pruning is necessary for

several reasons:

• To establish and maintain awell-formed permanent frame-work for the vine

• To obtain a balance betweenvegetative growth and fruitproduction

• To develop a canopy that usesavailable light efficiently (forphotosynthesis), yet is openenough to obtain maximumfruit quality and flower budformation for next year’s crop.An open canopy also facilitatesharvest and reduces the risk offungal diseases such as botrytis

• To maintain consistent yieldand fruit size

All species of kiwifruit can bepruned in a similar manner.However, there are many differentways to prune a kiwivine. Thefollowing description covers thebasic techniques.

Dormant pruningDormant pruning of kiwivines

is best done in late December tolate January in the Pacific North-west. Late-pruned vines may haveexcessive sap flow, which mayweaken vines.

In kiwifruit, flowers are pro-duced on current-season shootsthat grow from buds developed on1-year-old canes (last year’sgrowth). Shoots that grow fromolder wood seldom produce fruitin their first season. Shoots frombuds that were heavily shadedduring the preceding season are

less productive than those frombuds that were exposed to the sun.That’s why it’s important to prunewell so that the canopy is openand well exposed to light.Research at Oregon State Univer-sity has shown that hardy kiwifruitstart initiating flowers for nextyear’s crop in July and thatshading reduces the number offlowers formed.

Our research has shown that inA. arguta, all 1-year-old canes andspurs are equally productive perfoot of length and produce asimilar fruit size, regardless of

cordon

fruitful shoot

Figure 5.—Mature portion of a kiwifruit cordon in production. Leaves are notdrawn to simplify the figure. Fruit are produced on shoots growing from lastyear’s growth. Winter pruning cuts are shown by .

fruitful cane (heading cut madeprevious winter)

winter pruning cut

spur

replacement cane(headed backin winter)

19

Figure 6.—Dormant portion of a mature kiwifruit vine cordon. Winter pruningcuts are shown by . Shoots labeled with an “F” fruited last season.

spur

cordon

replacementcane

replacement cane

F

F

F FF

F

F

FFF

F

where they originated (cordon,2-, or 3-year-old wood). That’swhy it’s easy to prune a kiwivinetoo lightly, leaving too manyfruiting buds. The most productivepart of long 1-year-old canes isfrom nodes 6 to 40. The buds atthe base of canes usually produceonly a vegetative shoot (noflowers). The fruitful buds pro-duce shoots that bear flowers fromnodes 6 to 12.

When mature, male andfemale plants should be pruneddifferently.

Female vines. When pruning amature vine, remove about70 percent of the wood that grewlast season. Most of the woodremoved is older wood thatalready has fruited. New fruitingcanes usually will have developedat the base of last year’s canes.Figure 5 shows a typical fruitingcane that developed from thepermanent cordon.

Replacement fruiting canes thatoriginate from the cordon may beleft to replace older wood in thefuture. Fruiting canes should beseparated by about 8 to 12 incheson the cordon. Head back replace-ment fruiting canes to forcegrowth next season, and tie themto the wires for support. Do not tiecanes too tightly or they’ll girdleduring the growing season.

Spurs (shorter fruiting brancheswith short internodes) oftenoriginate from the older wood. Donot remove them unless necessary,as they also are fruitful (Figure 5).

Remove most of the older woodback nearly to the cordon. Leaving“stubs” of older wood may be anadvantage, as new vegetativeshoots often originate at thislocation rather than randomly

along the old cordon. This facili-tates management.

When necessary, you can leavesome 2-year-old wood with its1-year-old wood attached forfruiting wood if 18 to 48 inches ofnew growth is present beyondwhere fruit was formed last season(Figure 6). Head back thesefruiting laterals to 2 to 4 buds in

fuzzy kiwifruit and to 8 to 12 budsin hardy kiwifruit beyond wherefruit was formed last year. Oftenyou can see where the fruit wasborne last year because the oldfruit stems (pedicels) do not falloff the vine. The area of the canethat bore fruit last year (normallynodes 6 to 12 in hardy kiwifruit)will not have buds present and

Maintaining Your Kiwifruit Vineyard

20

thus will not produce any shoots.Expect from 25 to 57 percent budbreak (typically about 50 percent).

Take care that 1-, 2-, andsometimes 3-year-old fruitingcanes are distributed evenly on thetrellis to avoid overcrowding inany area of the canopy.

Remove twisted and tangledgrowth, shoots that cross from oneside of the vine to the other, andwind- or cold-damaged shoots.Mature vines, spaced at 15 feet inthe row, should have 30 to 45fruiting canes per vine (spaced at8 to 12 inches on both sides).

Male vines. The goal whenpruning male vines is to produceas many flowers as possible forpollination, while keeping the vinemanageable. It is best to prunemale vines only lightly in thedormant season—just enough to

remove tangled shoots and keepvines manageable. After flowering(late June), prune male vines,using the same principles asdiscussed for the female vines.

In hardy kiwifruit we havefound that the cordons of femaleand male vines need to bereplaced every 3 to 4 years. Toreplace the cordon, lay a vigorousvegetative shoot down along thecenter training wire in eachdirection. Do this the year beforeyou plan to remove the oldcordon. The following season,lateral shoots will be formed alongthe new cordon; space these asdiscussed in “Establishing YourKiwifruit Vineyard.” Once a goodreplacement cordon and fruitingcanes are established, cut off theold, unproductive one.

Summer pruningIn the Pacific Northwest,

growers generally have done littlesummer pruning other than toremove unwanted suckers fromthe base of the vine and hedging.Hedging is done only in the T-barsystem to keep the aisles open.Use a sickle bar to cut shoots backto about 2 feet from the edge ofthe trellis. Some thinning(removal) of excessive vegetativeshoots not needed for next yearalso can be done. Take care not toprune excessively in the summer,as fruit and sometimes canes maybecome sunburned.

Some shoots in hardy kiwifruitwill naturally stop growing. Earlyin the growing season, afterbloom, the tip of some shoots willdie, leaving a dead, black tipapproximately 6 inches long. Thisis natural and does not indicate thepresence of a disease.

21

Harvest, Handling,and Storage of Kiwifruit

Most of theresearch onharvest,handling,and storage of

kiwifruit has been done with themost common kiwifruit growncommercially, Hayward(A. deliciosa). Therefore, most ofthe information presented here forhardy kiwifruit is based on growerexperience or observation ratherthan on research findings.

Fruit MaturationKiwifruit continue to increase

in fresh weight and size untilharvested, but the most rapid sizeincrease occurs the first 100 daysafter bloom in Hayward and60 days in Ananasnaya. Still,picking fruit too early inAnanasnaya can lead to a signifi-cant loss in fruit size and yield.Kiwifruit are one of the few fruitsthat retain a high starch content atmaturity.

Starch hydrolysis, or break-down, continues afterharvest, even at 32°F,and is essentiallycomplete within afew weeks afterharvest. Freshly

harvested kiwifruit canbe cleared of starch in 4 to 6

days if held at 68 to 77°F (20 to

25°C) in an ethylene environment.A decline in starch content as

fruit mature is coupled with anincrease in percent soluble solids(sugars). The increase in solublesugars that begins as kiwifruitapproach maturity continues afterharvest and peaks about the timethat starch hydrolysis is complete.As fruit mature on the plant, partof the increase in sugars occurs asthe plant produces more carbohy-drate through photosynthesis.

With advancing maturity, theaccumulation of carbohydrateslows, yet the sugar contentcontinues to increase. At this time,the increase in sugars primarily isdue to the conversion of storedcarbohydrates (mainly starch) tosugars. Kiwifruit contain lots ofglucose and fructose and a smallamount of sucrose.

At the peak of carbohydrateaccumulation, fruit have essen-tially achieved their best potentialeating quality, and further delaysin harvest will not improve flavor.

Fruit size within a vine is notrelated to fruit maturity. Also,most cultivars show little visualchange in fruit appearance as theymature. For these reasons, it isunreasonable to attempt multipleharvests from a vine. Haywardtends to have more uniformripening of fruit within a vine

22

|than do the arguta cultivars(Ananasnaya, for example).

Soluble solids (sugar) content(°Brix) is the most commonlyused maturity index for kiwifruit.In California, Hayward areharvested at a 6.5 percent solublesolids standard (6.5 °Brix). Fruitthen will attain good quality instorage. In Oregon, Hayward fruitdo not reach 6.5 °Brix until theend of October to early November,usually after the leaves fall!Soluble solids content is about12 to 18 percent when ripe.

In the arguta cultivars, fruit areat about 18 to 25 percent solublesolids when ripe. However, toincrease shelf life and facilitateharvest, this species of kiwifruit isharvested between 8 and 14 °Brixwhen fruit are still firm—usuallyin early to mid-September inOregon. Vine-ripened fruit(October) become very soft, andthe stem pulls from the fruitleaving a wound; these fruitcannot be stored.

The soluble solids content ofkiwifruit can be measured with ahand-held refractometer. Cut awedge extending from the stem toblossom end of the fruit andsqueeze the juice from the fruit.

Starch in unripe kiwifruit willcloud the solution and makerefractometer readings difficult.Pour the sample through a fewlayers of facial tissue to clear thesolution. For a non-temperature-corrected refractometer, follow thedirections for accurate °Brixreadings carefully.

A sample of kiwifruit can beripened fairly easily to monitorripe fruit soluble solids content,

but this takes several days. Toripen small samples, place fruitwith fresh apples (to provide asource of ethylene) in a slightlyvented plastic bag. At 77°F(25°C), ripening takes 4 to 5 days.

HarvestingOnce the minimum maturity

standards have been achieved, allof the fruit can be harvested in onepicking. Harvest fruit by hand. Toharvest fuzzy kiwifruit, pickersshould wear soft cotton gloves toprevent damage to the skin (fuzz)of the fruit. Fruit are easilydamaged by rough handling eventhough they seem quite hard atthis stage of maturity.

When arguta fruit are too ripeor soft when picked, fruit will tearat the stem end. This is not aproblem when harvesting at 8 to14 °Brix and fruit are hard. Riperfruit are delicious, but their shelflife is very poor. Enjoy themimmediately or keep separate fromother fruit.

Pickers should use gloves orclip their nails short to avoid dam-aging the skin of hardy kiwifruit.Pick hardy kiwifruit without thestem. Break the stem at the fruit–stem juncture, by hand.

Keep fruit in the shade whileawaiting transport, and cool themas quickly as possible to maximizestorage life. Field heat must beremoved quickly from fruit afterharvest, because the fruit can losewater quickly. After 3 to 4 percentwater loss, fruit may appearshriveled, especially at the stemend. This is less of a problem withA. deliciosa in the Pacific North-west (compared to California),

because fruit are harvested inOctober–November.

Softening of kiwifruit also istemperature-dependent. Fruit at41°F (5°C) soften three timesfaster than fruit at 32°F (0°C).Avoid exposing fruit to ethylene, agas that promotes ripening andfruit softening.

Fruit usually are sorted for sizeand quality before packing. If fruitare not packed immediately, storethem in large bins.

StorageStore kiwifruit as near to

32°F (0°C) as possible at 90 to95 percent relative humidity withethylene gas scrubbers to maintainan ethylene-free atmosphere.Make sure oxygen is circulated tothe cooler. Low oxygen levelslead to anaerobic respiration,making fruit nonmarketable due toan off flavor. Even when fruit areheld at this temperature, aboutone-third to one-half of theremaining flesh firmness may belost per month of storage (Hay-ward). Fruit are sensitive tofreezing injury; be careful that thetemperature of the fruit does notdrop below 32°F.

For long-term storage, use ofcontrolled atmosphere (5 percentCO

2, 2 percent O

2) has been

effective for Hayward, providedtemperature is kept at 32°F and anethylene-free atmosphere ismaintained. Note that only bat-tery-operated forklifts should beused in storage rooms to avoidgenerating ethylene. Monitorlevels of ethylene in storage on aregular basis, because a week or

23

more of 10 ppb ethylene willhasten fruit softening.

Hayward fruit can be stored3 to 6 months under ideal storageconditions. Hardy kiwifruit,however, can be stored less than

2 months, because fruit are moreperishable.

Before shipping, fruit can beexposed to ethylene to trigger theripening process. Althoughfuzzy kiwifruit are sold loose,

unwrapped, hardy kiwifruit arebest sold in clamshell packagesthat maintain a higher humidity(to prevent shriveling) and preventfruit damage.

Harvesting, Handling, and Storage of Kiwifruit

24

Pests

Although a fewpests arereported to be ofconcern inkiwifruit (see

“Site Selection”), the only peststhat have been observed to causeproblems in hardy kiwifruitvineyards in Oregon arephytophthora root rot and possiblythrips. Threshold levels have not

been established, but high popula-tions of thrips at bloom arethought to cause scarring injury(ladderlike appearance) to fruit.Fruit rot (botrytis) has beenobserved in cases of less-than-ideal or longer-than-recommendedstorage conditions. No disease orinsect pest has been found associ-ated with the shoot tip die-backthat is observed in the summer(see “Summer pruning”).

© 2004 Oregon State University

Pacific Northwest Extension publications are jointly produced by the three Pacific Northwest Land-Grant universities: Oregon State University, Washington,State University, and the University of Idaho. Similar crops, climate, and topography create a natural geographic unit that crosses state lines. Since 1949, thePNW program has published more than 550 titles, preventing duplication of effort, broadening the availability of faculty specialists, and substantiallyreducing costs for the participating states.

Published and distributed in furtherance of the Acts of Congress of May 8 and June 30, 1914, by the Oregon State University Extension Service, WashingtonState University Extension, University of Idaho Cooperative Extension System, and the U.S. Department of Agriculture cooperating.

The three participating Extension Services offer educational programs, activities, and materials—without regard to race, color, religion, sex, sexualorientation, national origin, age, marital status, disability, and disabled veteran or Vietnam-era veteran status—as required by Title VI of the Civil RightsAct of 1964, Title IX of the Education Amendments of 1972, and Section 504 of the Rehabilitation Act of 1973. The Oregon State University ExtensionService, Washington State University Extension, and University of Idaho Extension are Equal Opportunity Employers. Published February 1998. ReprintedApril 2005. $3.50

For more informationMany Extension Service publications may be viewed or downloaded from the Web:

Oregon State University—http://extension.oregonstate.edu/

University of Idaho—http://info.ag.uidaho.edu/

Washington State University—http://pubs.wsu.edu/