Growing Kiwifruit Contents

PNW 507 • Reprinted September 2000 $2.50 Growing Kiwifruit Contents

Bernadine Strik, Extension berry Kiwifruit Cultivars crops specialist, and Helen Cahn, research assistant, Oregon State “Fuzzy” Kiwifruit ...... 2 University. Hardy Kiwi ...... 3 This publication replaces Oregon Kolomikta Kiwi ...... 4 publication EC 1464, Growing Silver Vine Kiwi ...... 5 Kiwifruit. Establishing Your Kiwifruit Vineyard Site Selection and Preparation ...... 6 Vineyard Planning, Planting, and Spacing ...... 7 Irrigation ...... 8 Fertilization...... 10 Trellis ...... 11 Training Young Vines ...... 12 Maintaining Your Kiwifruit Vineyard Fertilization...... 15 Irrigation ...... 16 Pollination...... 16 Fruit Thinning ...... 16 Pruning and Training ...... 17 Harvest, Handling, and Storage of Kiwifruit Fruit Maturation...... 19 Harvesting...... 20 Storage ...... 20

2 Kiwifruit Cultivars

B. Strik and H. Cahn iwifruit are Although some people claim native to they eat the skin of fuzzy kiwi, southeast Asia. most peel these fruit. However, There are more the hardy, kolomikta, and silver than 50 species in vine kiwifruit have very edible Kthe genus Actinidia, and many skin. You can pop these delicious, have commercial potential. small fruit right into your mouth. The most common kiwifruit Kiwifruit are relatively high in species grown commercially is acid, reaching nearly 2 percent of Actinidia deliciosa cultivar fresh weight at maturity and Hayward. Consumers are very declining after harvest. Kiwifruit familiar with this brown, fuzzy are one of the best natural sources fruit. of vitamin C, with a level of at Fuzzy kiwi are grown commer- least twice that of the orange. cially in New Zealand, Italy, The fruit of most common Japan, France, Australia, Greece, kiwifruit species and cultivars Chile, and California. There is have green flesh that does not some commercial production in brown when cut. Oregon and Washington; however, Fuzzy kiwifruit can be stored this species is not extremely hardy for months after harvest. However, and may suffer cold injury in the hardy and kolomikta kiwis can some years in the Pacific North- be stored for only 2 months at west. most at 32–35.5°F (0–2°C). More hardy kiwifruit species The kiwifruit is a dioecious also are available. They include plant—it has separate male and the following: female plants (with the exception • A. arguta, known as the hardy of a few self-fertile cultivars). It is kiwi or arguta (marketed as essential to plant male vines for baby kiwi in Oregon and grape pollination and crop production. kiwi in British Columbia). This Plant male and female vines of species shows promise for the same species. In general, commercial production in the 1 male is required for every 6 to United States. 10 females. Self-fertile cultivars require no male pollinator, al- • A. kolomikta, also though fruit size may be larger known as kolomikta with cross-pollination. or Arctic Beauty Yield per plant varies with • A. polygama, or species and cultivar. Hayward silver vine (A. deliciosa) yields from 25 to 1 200 pounds per plant, whereas Fuzzy kiwifruit can be grown in Hayward A. arguta yields from 50 to Oregon and Washington. Hayward Hayward is the cultivar usually 100 pounds per plant. needs a growing season of about found in stores. Its large, fuzzy, A. kolomikta and A. polygama 225 to 240 frost-free days. How- brown fruit with good, sweet leaves contain a substance that has ever, although this species should flavor has made it popular. Shoots an effect similar to catnip. In tolerate temperatures down to are sensitive to frost injury in China, kiwivine leaves reportedly 10°F (-12°C), plants may be spring. This cultivar is recom- are fed to large cats as a sedative. damaged at slightly higher tem- mended only for areas of Oregon You may find that cats become a peratures. and Washington with mild pest of your new kiwifruit plant- Cold damage usually occurs winters. ing! when temperatures drop during Ripening date: October 7–12 The information below on the night after a warm spell. The Fruit weight: 80–90 grams ripening dates, fruit weights, and trunk usually is damaged, which Vine growth: vigorous plant performance is approximate. weakens older plants and some- It is based on limited test results times kills young vines. Although Bruno from a cultivar planting at North methods such as wraps and plastic Bruno produces a large cylin- Willamette Research and Exten- sleeves may help protect the trunk drical fruit that is darker brown sion Center (NWREC), Aurora, against freeze injury, they are not than Hayward. It has a lower Oregon. Performance may vary always effective. The trunk’s winter chilling requirement with location. sensitivity to cold decreases with (50–250 hours at 32 to 45°F), and age. therefore may be more sensitive to “Fuzzy” Kiwifruit Young kiwifruit shoots and fruit late winter cold spells, particularly are very sensitive to frost injury. after a warm period. Actinidia deliciosa, fuzzy Temperatures of 30°F or less kiwifruit, is the most widely (-1°C) for only 30 minutes can Saanichton 12 available species. Generally, fruit severely damage shoots in the This cultivar comes from are large, with a green skin spring and fruit in the fall. Still, Vancouver Island, British Colum- covered with brown fuzz. Vitamin these kiwifruit can be grown bia, where it has been grown for C content ranges from 100 to successfully with overhead more than 30 years. Fruit are 200 mg per 100 grams fruit. The irrigation for frost protection. large, somewhat more rectangular most common commercial culti- Although many other fuzzy than Hayward, sweet, and of good var is Hayward, which is found in kiwifruit cultivars are available in flavor. It seems more hardy than supermarkets throughout the other production Hayward. world. However, other varieties regions, the follow- Ripening date: October 1 also are available. ing cultivars are Fruit weight: 70–80 grams available and have Vine growth: vigorous been tested in the Blake Pacific Northwest. This is a relatively new cultivar. All produce bright It is claimed to be “self-fertile,” green-fleshed fruit. but it does benefit from cross- Ripening dates pollination. Fruit are smaller than given below are based Hayward or Saanichton 12 and are on when fruit reached ° more oval in shape. Flavor is 6.5 Brix (percent sugar) at inferior to Hayward and NWREC, a harvest date Saanichton 12. criterion for long-term storage Ripening date: October 1 (see “Harvest, Handling, and Fruit weight: 60–70 grams Storage of Kiwifruit”). Vine growth: vigorous 2 Kiwifruit Cultivars

Male (A. deliciosa) A. deliciosa. Fruit are smooth Ananasnaya A pollinator is required for all skinned (skin can be eaten), This is the most popular hardy fuzzy kiwi. There are many generally green in color, and much kiwifruit cultivar currently avail- cultivars/selections of males smaller than the fuzzy types. The able. Its Russian name means available. Examples include flavor is excellent, but varies by “pineapple-like.” You also may Matua, Tomuri, Cal Chico No. 3, cultivar. Vitamin C content is hear this cultivar referred to as Chico Early, and Chico Extra very good at 10 to 70 mg per “Anna.” Early. 100 grams fresh fruit. Fruit are of very good quality, In France, hardy kiwi are with a good aroma and sweet, Hardy Kiwi cultivated commercially, but intense flavor. They have a green acreage is limited due to market- skin that develops a purple-red This kiwifruit species, ing limitations—small fruit size, blush in full sun. Skin may be ° A. arguta, is hardy to -10 to -25 F short shelf life, and a limited slightly tough. ° (-23 to -32 C) under most condi- ripening period. Also, the fruit on The cultivar Ananasnaya tions. Damage to the trunk from a given plant ripen unevenly, brought to Oregon is A. arguta. cold temperatures rarely occurs in which makes harvest difficult However, the Russian cultivar Oregon or Washington; however, unless fruit are picked under-ripe Ananasnaya is A. kolomikta; frost damage to young shoots is and forced to ripen. Vines are very more than one cultivar with the more common. vigorous, and considerable same name may be available in Maximum hardiness levels pruning is required to keep growth nurseries. given for this species reflect only under control. Harvest date: September 14–30 midwinter hardiness. This species In general, hardy kiwifruit do Fruit weight: 9–14 grams has a low chilling requirement not store as well as the fuzzy Vine growth: very vigorous (winter rest period satisfied by types. Therefore, you likely will ° 74-49 temperatures at 32–45 F) and may see these kiwifruit in stores up to This numbered selection/ be sensitive to cold injury at only a couple of months after fall cultivar came from a USDA higher temperatures when warm harvest. program in Chico, California. weather precedes a cold spell, Currently, relatively little hardy This cultivar produces very good particularly in late winter. kiwifruit is grown commercially. quality fruit of similar size and Unfortunately, warm tempera- However, you no doubt will hear quality to Ananasnaya. tures in February or March may and see more about these types, as Ripening date: September 7–14 promote early bud break, making they do have good quality, attrac- Fruit weight: 7–12 grams this species very susceptible to tive fruit. Vine growth: very vigorous frost damage of the young shoots. Certainly, the hardy kiwifruit Only additional testing will show are well suited to the home garden Meader how much of a problem this may and, with an appropriate market, be for our region. We presently are not testing this to commercial production as well. cultivar at NWREC. However, it is Keep in mind that young vines Fruit of these hardy kiwi are may be more cold sensitive. reported to produce good quality, best when ripened on the vine to medium-sized fruit. Note that a Protect them with trunk wraps maximize development of aroma (see “Establishing Your Kiwifruit male “Meader” also is available; and flavor; however, shelf-life do not be confused. Vineyard”). then is shortened. The following Hardy kiwi plants are very harvest dates are based on sugar vigorous and produce a good levels of 8 to 9 °Brix. (If left on quality, highly aromatic fruit that the vine, the fruit will reach 18 to is quite different from the fruit of 25 °Brix.)

3 A. arguta var. cordifolia slightly less hardy than other variegated pink leaves, particu- Not yet widely tested in the A. arguta at 0 to -10°F (-18 to larly in the male. Pacific Northwest. Fruit are -23°C). The fruit are small to medium reputed to be of good flavor and Harvest date: September 1–4 sized, but are very sweet, with very sweet. Plants are very Fruit weight: 4–9 grams good aroma and flavor. Fruit are vigorous and produce high yields. Vine growth: moderate vigor valued for their exceptionally high Flowers may be wind pollinated. with lower yield per vine than the vitamin C content—700 to 1,000 other hardy kiwi. mg/100 grams fruit (10 times Ken’s Red higher than Hayward and 20 times Not widely tested in the Pacific Male higher than citrus). Northwest, this kiwifruit from Pollinator for above A. arguta Fruit are best when ripened on New Zealand is a cross of species. About 1 male is needed the vine to maximize aroma and A. arguta var. cordifolia and for every 8 females. There is flavor development; however, A. melanandra. Fruit are nearly evidence that A. arguta cultivars shelf life then is shortened. square to cylindrical with a “nib” can be pollinated by A. deliciosa It has been difficult to establish at the tip. They are bright green in males, which produce more pollen A. kolomikta at NWREC. Vines summer and turn red-skinned late than the arguta males. However, planted in 1990, even after in the season. Vines are very A. deliciosa males are much less 4 years, grew little and produced vigorous. hardy than A. arguta males; thus almost no yield. Thus, it is hard to you risk crop loss to cold injury evaluate their performance relative Geneva when using the fuzzy males. to the hardy kiwi. This cultivar has not been Other cultivars/selections that Perhaps this species is more widely tested in the Pacific may be available include sensitive to wet soil or phytoph- Northwest, although there are Dumbarton Oaks, 74-45, 74-8, thora root rot—a possible reason preliminary results from British and Michigan (reported to have for its poor growth at NWREC. Columbia. Plants ripen earlier almost twice the fruit size of There also are reports that than Issai and Ananasnaya and are Ananasnaya). However, these A. kolomikta requires some shade about the same size. Fruit have a have not been tested in Oregon. for optimal growth. This species good flavor. also has not performed well in Issai (self-fertile) Kolomikta Kiwi trials in British Columbia. This cultivar from Japan is less These kiwi types, A. kolomikta, Nevertheless, the following vigorous than the other hardy are hardy to -40°F (-40°C), but cultivars may perform well at kiwifruit cultivars listed above. shoots are sensitive to frost other sites and certainly would Fruit are smaller in size, some- damage. In the Willamette Valley, make good ornamental fruit plants what cylindrical, come to a point, Oregon, A. kolomikta cultivars in the home garden. This species and are fully green. Flavor and have been found to break bud does not have the commercial aroma are very good. Harvesting earlier than arguta types in late potential of A. arguta. is somewhat more difficult than winter. For example, all shoots Krupnopladnaya were killed by cold in February the other hardy kiwi, because fruit This cultivar, “large fruit” in 1995. Available cultivars differ are smaller and ripen rather Russian, is the largest of the arctic greatly in fruit shape, size, color, unevenly within a cluster. This beauties tested in Oregon. Flavor and flavor. Fruit of kolomikta are cultivar, although self-fertile, is good and sweet. Plants have smaller than those of arguta produces larger fruit with seeds low to moderate vigor compared kiwivines. Plants are considered when cross pollinated. Vines are to A. deliciosa. good ornamentals because of their

4 Kiwifruit Cultivars

Pautske Silver Vine Kiwi flavor. Plants are moderately This is the most vigorous of the vigorous, but more susceptible to This species of kiwifruit, A. arctic beauties tested in Oregon. cold injury than arguta or polygama, is called silver vine for Fruit are large and of good quality. kolomikta. Some clones are self- the silvery-white color of the Plants are more vigorous than fertile. young leaves. Fruit have orange those of Krupnopladnaya, but still This species does not have skin and flesh, and are cylindrical have lower vigor than A. deliciosa. much potential for commercial with a point at the base. Although fruit production. However, it does Male several sources say fruit are edible make a nice ornamental. A. kolomikta male needed to with a sweet, peppery taste when Harvest date: September 1–4 pollenize the above cultivars. ripe, we have not had good Fruit weight: 6–9 grams success with this species at Vine growth: moderate to low NWREC. Our fruit goes from vigor at NWREC green and unripe to orange and soft with an astringent peppery

5 Establishing Your Kiwifruit Vineyard B. Strik ine growth and winter injury, particularly to the fruiting habit of trunk, if temperatures fluctuate both fuzzy and from warm to cold in late winter. hardy kiwifruit are A. arguta vines also are sensitive similar. The to spring frost damage to young followingV information on vineyard shoots. establishment applies to all the Male vines are less hardy than aforementioned species unless female vines (documented in differences are noted. Oregon). There are several ways to help Site Selection prevent freeze and frost injury: • Do not plant in low areas or and Preparation cool sites. Proper site selection, soil • Remove barriers (e.g., trees) to preparation, irrigation system cold air drainage. design, planting design, and • Keep in mind that clean, training are essential to develop- cultivated sites are warmer ing a productive kiwifruit vine- during frost periods than sites yard. with permanent cover crops. Site selection • Do not cultivate immediately The single most limiting factor prior to a projected frost, for fuzzy kiwifruit production is because this reduces heat temperature. A. deliciosa Hayward transfer from soil to air at night. can withstand temperatures as low • Use overhead irrigation systems as 10°F (-12°C). Although the in areas susceptible to late buds of Hayward have a high spring frosts (see “Irrigation”). chilling requirement (700 to Chemicals that reduce vine 800 hours), the vines are very transpiration (i.e., anti-desiccants) prone to frost injury during the have not been shown to reduce growing season. Cold injury to frost injury in kiwifruit. Hayward has occurred in some winters in the Pacific Northwest. Soil Dormant A. arguta vines are Kiwi vines do best in deep, much more cold hardy than the well-drained soils. They are very fuzzy types (to -10 to -25°F or -23 sensitive to standing water, to -32°C). However, young vines especially after bud break in of this species also can suffer spring. Research in New Zealand

6 Establishing Your Kiwifruit Vineyard has shown that if roots are water- logged for 3 days or more, the root Table 1.—Irrigation water guidelines. system and vine growth are chloride < 70 ppm severely damaged. bicarbonate < 200 ppm In California, it is recom- boron < 0.25 ppm mended that kiwifruit be planted sodium < 50 ppm on 3 feet of well-drained soil. electrical conductivity, EC x 10 < 0.75 However, Hayward vines have grown well on soils with an effective rooting depth of 2 feet, Young kiwifruit vines compete Vineyard provided the water table is lower poorly with weeds, so eliminate as than this. many perennial weeds as possible Planning, Planting, Another option is to plant vines before planting. A permanent on raised beds (at least 1 foot cover crop or a natural weed strip and Spacing high). This is advisable in heavy may be maintained between rows. It costs from $8,000 to $12,000 soils, since it also may protect per acre, not including land cost, against phytophthora root rots. Water to establish a kiwifruit vineyard Install well-designed drain tiles A plentiful supply of good and bring it to production. It takes to improve drainage if necessary. quality water is required for 3 or more years after planting to Ripping the soil below the row kiwifruit production. Plants need produce a commercial crop. before planting also can benefit 40–48 acre-inches of water a year. growth. Table 1 shows irrigation guide- Planting design The optimum pH for Hayward lines that are considered safe in For a T-bar trellis, vines com- is between 5.5 and 6.0. Vines California. monly are planted 15 to 18 feet show poor growth at a pH above apart in rows 15 feet apart, 7.2. It is not known if other Wind damage resulting in 160 to 190 plants per species differ in pH requirements. Long shoots in spring and acre. For the pergola, you may summer are very susceptible to want to space rows 20 feet apart Previous cropping history wind damage or breakage. Not (see “Trellis”). Kiwifruit are susceptible to only can wind cause fruit loss, but Kiwifruit vines are extremely verticillium wilt. Avoid planting in it also may reduce economic vigorous. Canes grow 6 to 12 feet soils with a history of strawberry, yields by rubbing the fruit. When per year, and occasionally 20 feet. black raspberry, potatoes, or other rubbed, fuzzy kiwi first lose their Higher density plantings may solanaceous crops. “fuzz” and then develop callus, increase production in the early Plants also are sensitive to whereas the hardy types develop a years, but in later years, over- phytophthora and root knot callused or scabbed area. growth and shading will require nematodes (Meloidogyne spp.). In windy areas, wind breaks excessive summer pruning. Although the literature relates to such as poplars help reduce The kiwifruit is a dioecious Hayward, it’s best to assume that economic losses. Plant wind plant—it has separate male and arguta is similarly sensitive. breaks to provide 200 to 250 feet female plants (with the exception Kiwifruit also are susceptible to of protection downwind. Make of a few self-fertile cultivars). Armillaria oak root fungus, which sure wind breaks are not planted Male vines are essential for may be present on sites previously close enough to the vineyard rows pollination and crop production. planted to oak trees. to reduce yield of the kiwifruit. In general, plant the same A preplant soil test for nema- species of male as the female todes is recommended. If nema- vines. Although A. deliciosa males todes or oak root fungus are are reported to be good pollinators present, use a preplant fumigation. of A. arguta females, they are 7 much less cold hardy than arguta thus killing the vine. On cold- needed, the vine trunk is not in males, and thus increase the risk injured, self-rooted vines, suckers the way. of crop loss to cold damage. can be trained up from below the Make the planting hole large Male and female vines must be winter-killed portion. enough to accommodate the roots present in a block and must flower Using rootstocks in kiwifruit without bending them. You may at the same time. In general, plant production could offer many trim the roots a little to make about 1 male plant for every 6 to advantages: them fit the hole. Do not dig the 10 female plants. • Reduced plant-to-plant variability hole deeper than needed. Do not You can achieve a 1:8 male- add any fertilizers, including • Vigor reduction female ratio with the following manures, to the planting hole, as design: • Greater tolerance for adverse the roots are very sensitive to soil conditions such as water- • Plant only female plants in all fertilizer burn. logging outside rows. Plant vines deeply enough just • Greater physiological cold to cover the top roots. Never • Plant the following row with a tolerance mound soil around the plant. male plant between every two Keep the soil moist enough to female plants. • Resistance to pests or diseases promote root growth, but don’t • Plant the next 2 rows of all • More precocious and higher- yielding vines over-water, which can cause female plants. anaerobic conditions that promote • Plant another row with a male However, research needs to be root rots. plant between every two done on rootstock possibilities in You can paint the trunks with a females. kiwifruit. mixture of 1:1 water and interior Plant 2-year-old bare-root or • Plant 2 more rows of all female white latex to help prevent container stock. If grafted, the plants. sunburn. Milk cartons also can scion (fruiting portion) should • Continue as above. protect against sunburn and have been grown for one season rodent feeding. Place a trunk If you plant a male every third before purchase. wrap around all species of vine in every second row, the ratio Purchase bare-root nursery kiwifruit vines. This helps reduce is 1:6. stock as close to planting time as the risk of cold injury to the Male plants in these planting possible. Don’t allow the roots to susceptible young vines. systems run at right angles to the dry out. Plant as early in the rows. For T-bar systems, you may spring as possible. Container- want to place males in every row, grown plants can be planted at any Irrigation as there is some evidence that bees time except midsummer. Good irrigation is critical for prefer to work down rows rather It’s a good idea to plant on good growth and production. than across. raised beds to reduce risk of Irrigate young plants enough to phytophthora. Carefully mark wet the root zone without keeping Planting your field prior to planting. the crown too wet; otherwise, Self-rooted vines perform better Planting all males first and then crown or root rot may occur. In in the Northwest’s cold winters. filling in with females is recom- young plants, the range between Although grafted kiwifruit are mended. too wet and too dry is narrow. available from many nurseries, Install your irrigation system Unfortunately, there is rela- planting kiwifruit on their own before planting (see “Irrigation”). tively little direct experience on roots in areas where cold injury Establish your trellis prior to, or water requirements of hardy may occur is recommended. just after, planting (see “Trellis”). kiwifruit in the Pacific Northwest. Severe cold spells can kill a Place the row posts between The following information relates grafted vine past the graft union, plants so that if post repair is

8 Establishing Your Kiwifruit Vineyard to Hayward production, but trunk, and the one near the trunk is Overhead sprinklers are best for should be a good starting point for removed (to keep the trunk frost protection, but may spot or other cultivars as well. relatively dry). When the plant is discolor the fruit when used in Growers often irrigate by 4 years old, two more emitters are summer. They also may leach experience rather than irrigation added 3 feet away from the trunk. nutrients from the leaves and scheduling tools. In kiwifruit, When plants are mature, increase incidence of fungus however, observing vines for California growers find it difficult diseases. trouble signs doesn’t work well, to supply enough water with four Some California growers use a because by the time water stress emitters per vine, so they add T assembly on the sprinkler riser symptoms are visible, damage has more emitters or switch to to switch from over-vine sprin- occurred. minisprinklers. For larger vines, klers to under-vine sprinklers. Vines under mild or moderate up to 10 emitters per vine may be They use the over-vine positions water stress have a subtle off-color necessary. for frost protection (shoots in the look, with the foliage turning spring, fruit in the fall) and switch blue-green. Other symptoms Minisprinkler systems to the under-vine position in include poor shoot growth, Under-vine minisprinkler summer. (Note that only fuzzy wilting, small fruit, sunburn, and systems, which produce a wetted kiwifruit are sensitive to fall reduced yield in the current and area of greater size, often are frosts, because hardy kiwifruit following season. preferred. In general, they wet mature earlier.) There are various types of more soil than drip emitters do, Impact systems work well if the irrigation systems. Unfortunately, are easy to install, and tend to plug canopies aren’t in the way, but there is no single best system. less frequently than drip emitters. they tend to use more water. Design a system that can supply They can be used to replace drip Under-vine sprinklers should be an average of 25 to 35 gallons of systems as vineyards age. In between vines in order to reduce water per mature vine per day young vineyards, however, impact on the trunk. during the growing season. minisprinklers tend to over- Irrigate vines once or twice per irrigate. Frost protection week. Surface mulch may help These sprinklers spray water in Over-canopy sprinklers can conserve soil moisture. a 6- to 18-foot diameter circle. provide 6 to 8°F frost protection, One full-turn minisprinkler per whereas under-vine impact Drip systems vine, located equidistant between sprinklers can provide about 2 to Drip systems economize on vines, should be adequate in 3°F protection. In California, 5 water use, but on lighter soils mature plantings. /16-inch sprinklers are used at a often supply water to only a Generally, they are narrow cone of soil. Frequent allowed to run 6, 8, irrigations are necessary, particu- or 12 hours, two to larly to young plants with small four times per root systems. However, as the week. crown tends to stay drier, risk of crown rot (phytophthora) may be Impact reduced. You can’t use drip sprinklers systems for frost protection. Impact sprinklers Drip irrigation systems com- also are used in kiwifruit monly are used in California in vineyards, especially in more young plantings. At planting, one mature plantings. They can be emitter is placed near each plant. placed over or under the The second year, two emitters are canopy. placed 12–18 inches from the

9 spacing of 30 x 40 feet (at 50 lb/ Fertilization Fertilize young kiwifruit vines inch pressure) to supply 0.1 inch/ monthly with small amounts of hour (50 gallons/acre/minute). It is relatively easy to burn the nitrogen. Ammonium nitrate and Start sprinkler irrigation before roots of kiwivines, so apply urea are good sources of nitrogen temperatures fall below the critical fertilizer cautiously. The following for kiwifruit. level and continue until tempera- recommendations are based on In the first year, apply no more tures are above critical levels. Hayward in California and New than 0.4 oz of actual N per plant Zealand. per month in May, June, and July (total of 12 lb actual N/acre based wires on 160 plants per acre). Spread the 5-6' nitrogen in a circle 6 to 12 inches from the base of the trunk. In the year after planting, apply 0.8 oz of N per plant per month in April, May, June, and July (32 lb N/acre total). Spread the fertilizer in a ring about 12 to 36 inches from the trunk. 6' Fertilize third- and fourth-year plants with 2 to 3 oz of actual N every other month from March through July (60 to 90 lb N/acre). You may liquid feed nitrogen to young plants on a 2-week to monthly interval instead of using granular fertilizer. Figure 1-A.—Standard T-bar trellis system for kiwifruit. Do not fertilize young plants with liquid or granular forms of

wires nitrogen later than July. Late 5-6' fertilization forces late vegetative growth that is very sensitive to cold injury. Once plants bear fruit, the crop load tends to suppress 45° angle late vegetative growth and reduce risk of fall frost damage. Other nutrients may be added in spring either foliarly or to the soil

6' surface. Base applications on nutrient needs/analysis. Kiwifruit vines tend to take up a consider- able amount of phosphorus (P) and potassium (K). Test soil for P and K prior to planting, and incorporate nutrients preplant if necessary. Do not use fertilizer Figure 1-B.—Winged T-bar trellis system for kiwifruit. containing potassium chloride, as kiwivines are very sensitive to chloride. 10 Establishing Your Kiwifruit Vineyard

Trellis Kiwifruit vines are not self- 6' supporting; their size, vigor, longevity, and heavy crop load 20' mean they need a strong, perma- nent support structure. Two main types of support structures or trellises are used in commercial kiwifruit production: the T-bar and the pergola. A pergola provides a single plane of canopy about 6 feet above the ground. The T-bar trellis system consists of posts in rows with a 6' cross arm at 6 feet high. T-bars are less expensive to horizontal stay 10' 6' assembly construct, less labor intensive, tie-back assembly better suited to bee pollination, Figure 2.—Pergola trellis system for kiwifruit. and they reduce the risk of botrytis infection. However, pergola are at least 6 inches in diameter, A common modification of the systems tend to produce more and drive them at an angle with T-bar is the winged T-bar, in yield per acre, and the fruit are the top of the post leaning 1 foot which an additional wing and wire less susceptible to wind damage. from perpendicular away from the are added to each side of the T-bar Also, once the full canopy is row. Anchor the end posts well. cross arm (Figure 1-B). Tying established in a pergola, the shade The top of the cross arm is down a cane from the center wire reduces weed growth. 6 feet above the ground. Cross onto the two wires pulls it into a arms usually are a 2 x 6 inch T-bar more natural curve. board bolted into a cut notch on A typical T-bar trellis consists the post. You can brace cross arms Pergola of posts with a 5- to 6-foot back to the post for added A pergola trellis is designed to (depending on row width) long strength. support a solid canopy of foliage cross arm extending across each Run a wire down the row from and fruit (Figure 2). Wires not post (Figure 1-A). The kiwivine the top middle and each side of only extend down the row, but fruiting canes are tied to wires on the crossarms (Figure 1-A). Two also are used as “cross arms” top of the cross arm. additional wires can be added, one (more commonly than using Use pressure-treated 4–6 inch between the center and each end wood) running perpendicular to diameter posts that are 8–9 feet wire. Use galvanized, high-tensile, the vine rows. The wires are long spaced at 15–20 feet down 12-gauge wire for the vine sup- placed 1 to 3 feet apart. the row. Square posts are easier to ports. Good wire tighteners are work with. Drive posts 2 to 3 feet needed to keep a strong tension on into the ground. Use end posts that the wires to support the vines and crop.

11 Training at frequent intervals to help larger (Figure 3-E). If vines did prevent breakage. not have adequate growth to form Young Vines Do not allow the shoot to wrap cordons the first season, head the Proper pruning during the around the stake. Concentrate trunk back about 2 inches below establishment years is necessary to growth into this shoot by remov- the trellis wire to force new buds establish a well-formed permanent ing suckers at the base of the vine early the next season. (Figure 3-B). framework for the vine. Develop- Second season ing or training young kiwifruit Remove all basal lateral shoots The objective in this season is vines into a bilateral cordon that break along the trunk. If the to develop two permanent cordons allows for easier management main shoot loses vigor and begins from two strong shoots growing in when the plants are mature. to twist slightly, top the shoot and opposite directions from the trunk Kiwifruit produce a crop on train up the strong new “leader” along the center wire. As each shoots (fruiting laterals) that grow (Figure 3-C). Continue to train the cordon grows, hang it over the from 1-year-old canes (last year’s trunk until it’s 2 to 3 inches above wire and wrap it every 18 to growth). In the first few years, you the wire (Figure 3-D). 24 inches to ensure that it’s train vines the same way for both If the shoot reaches the wire securely attached to the wire. the pergola and the T-bar system. early in the season, you may try to Retain lateral branches that Prune dormant kiwivines in late form the cordons in the first year. are produced along the cordons December to mid-February in the To do so, top the shoot to about at about 8- to 12-inch intervals Pacific Northwest. Later pruning 4 inches below the training wire to (Figure 3-F). Carefully tie these may cause excessive sap flow. encourage lateral branch forma- tion. This forms a nice “Y” for the canes to the outer trellis wires. First growing season cordons. Select two shoots, Remove all others by summer The main objective during the growing in opposite directions, pruning before they twist around planting year is to develop a and train them along the center the shoots you want to keep. single, straight trunk. At planting, wire to form the two main arms, In the dormant season, prune prune plants back to one or two called cordons (Figure 3-E). the main cordons and the retained 1 buds (above the graft union in Another option is to train the lateral canes back to wood /4 inch grafted plants) (Figure 3-A). trunk up one way along the wire in diameter or larger (Figure 3-F). Once shoots start to grow, and wait until the next season to The first crop will form on shoots select one vigorous shoot to train train a shoot the other way. This from these canes in the third year. upward as the trunk. Place a stake results in cordons of unequal age, Pruning the canes during the beside the shoot to facilitate which may make management dormant season encourages training. String from the wire to more difficult. fruiting the following year. the stake can add support as well. During the first dormant Remove any suckers and new Tie the shoot to the stake (not too season, head back the cordon(s) to growth on the trunk (Figure 4). 1 tightly or you’ll girdle the shoot) wood of /4 inch in diameter or

12 Establishing Your Kiwifruit Vineyard

center wire

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

center wire

(E) (F)

Figure 3.—Training a young kiwifruit vine. (A) Prune to 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. 1 (E) Choose two shoots to form cordon, one each way on wire. Head back to ⁄4-inch diameter in dormant season (Year 1). (F) Shows shoot growth Year 2. Pruning cuts in dormant season Year 2 are shown.

13 Third season (Figure 4). Fruit in the third year Training of vines to a T-bar and Continue to extend the cordons, may sunburn due to inadequate pergola system is similar. In a if necessary, by training the canopy cover. Do not overcrop the pergola, the vines are grown as strongest shoots down the center vine. It may be a good idea to straight, single trunks until they wire until they’re within about remove some of the fruit to divert reach the top of the structure. A 1 foot of the cordon of adjacent more energy into vegetative single strong permanent leader vines. Do not allow them to twist growth. (cordon) then is allowed to grow tightly around the wire, because In the third dormant period, in each direction along the main this may restrict sap flow later. prune so that 15 to 20 well-spaced wire. Continue to train lateral lateral canes remain on the vine, To form the canopy of a branches perpendicular to the depending on vigor. Remove any pergola, develop a system of cordons (Figure 4). Do not train suckers or side growth on the fruiting canes from the cordons at shoots along the outer wires trunk. right angles to the wires. Fruiting parallel to the cordon; they will The permanent vine structure canes can be retained longer on cause too much competition for should be established by the pergolas and may be more perma- light. fourth year. Future pruning will nent than on T-bars. Fruiting In the third year, concentrate on renew fruiting canes and maintain laterals or shoots develop on the developing the vine’s framework. the vine framework and crop load. fruiting canes. It takes up to Fruit will form on shoots pro- See “Maintaining Your Kiwifruit 7 years to develop a full canopy in duced on last year’s growth Vineyard” for diagrams/descrip- a pergola. tions of pruning producing vines.

wires

center wire

wires

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

14 Maintaining Your Kiwifruit Vineyard B. Strik t is essential to maintain needed for early season growth your kiwifruit vineyard and fruit set in May–June. A well for optimum growth second application of granular N, and productivity. Pruning the remaining one-third, is recom- probably is the most mended in May–June. challengingI aspect of vineyard Plants should have good soil maintenance. moisture when they are fertilized. Most of the research and Irrigate first, wait 1 to 2 days, then experience on kiwifruit production fertilize; or fertilize after a good is with Actinidia deliciosa, rainfall. particularly Hayward. Unfortu- You can substitute liquid nately, there is relatively little fertilizer applied through the direct experience with hardy irrigation system for dry fertilizer. kiwifruit production. The follow- When applying liquid fertilizers ing information should, however, containing N, use about 10 lb provide a good starting point for of actual N in each application production of hardy kiwifruit as from April through July. Higher well as the fuzzy types. rates of liquid N, 20 lb per appli- cation, have injured roots on Fertilization lighter soils. Base fertilization with other It is relatively easy to burn the nutrients on tissue and soil analy- roots of kiwivines, so apply sis. Critical levels for leaf samples fertilizer cautiously. When apply- taken in late August in California ing granular N, be sure to broad- and for New Zealand are given in cast it over the entire root zone Table 2 (recommendations from area; concentrating it near the both areas are combined). It is not trunk can burn roots. Leaf necrosis known if species differ in nutrient is a symptom of fertilizer root needs or if critical levels vary by burn. region. However, these values can Mature vines, of 5 to 7 years be used as a guide. and older, use about 1 lb of actual Based on experience in New nitrogen (N) per vine per year, or Zealand and California, growers about 190 lb N/acre/year (with typically apply the following as a 15 x 15 foot rows). maintenance application: Apply about two-thirds of the 55 lb/acre phosphorus in Febru- nitrogen in March at bud break as ary–March; and 80–130 lb/acre a broadcast application under the potassium split between Febru- canopy. This provides the nitrogen ary–March, April, and May. 15 Maintain soil pH at about 6.0 Judging vine water needs is Kiwifruit flowers are pollinated with lime application in the fall. difficult. At this time, it’s not mainly by insects, although wind Kiwifruit seem to be sensitive known whether irrigation require- may play a minor role. Honey to chlorine, so avoid any fertilizers ments in the Pacific Northwest bees are the main pollinator used with chloride. differ from those in other regions. in kiwifruit vineyards. Based on information from British Kiwifruit flowers do not Irrigation Columbia, Canada, vine water use produce nectar and are relatively ranges from 25 to 35 gallons/vine/ unattractive to bees. About three The water a vine loses through day (at 70 to 80°F). to four hives per acre are needed transpiration must be replaced by Irrigation for frost protection to adequately pollinate kiwifruit. irrigation or rainfall. On a warm also is necessary to protect young Place these in the vineyard no summer day in California, mature, shoots in spring and potentially sooner than 10 percent bloom of full-canopy kiwifruit vines can fruit in fall. See “Establishing the female vines. transpire 7,000 to 8,000 gallons of Your Kiwifruit Vineyard” for In some years, you may have water per acre per day. Transpira- more information. no male vines in flower as a result tion occurs when leaves use of winter injury to male plants carbon dioxide to produce carbo- (they are less hardy than the hydrates through photosynthesis. Pollination females). In this case, no naturally Irrigation is necessary to keep For fruit to be produced, male produced pollen will be available. vines growing and productive and and female vines must be present To get a crop, the females will to maximize fruit size. Water in a block and must flower at the have to be pollinated artificially. stress can reduce fruit size, limit same time. Male flowers produce Call your county Extension agent flower numbers (through reducing viable pollen for only the first 2 to for more information on sources flower bud initiation), and cause 3 days after opening. However, of pollen and methods of artificial premature fruit drop. Summer female flowers are receptive to pollination. drought can cause leaf drop and pollen for 7 to 9 days after open- premature fruit ripening in arguta; ing, even when the petals have however, fruit ripen more started falling. Fruit Thinning unevenly and are of poorer flavor. Pollination is extremely impor- Fruit thinning, or removing Severe drought also may cause tant in kiwifruit production. Large fruit after set, can be done to fall flowering, which reduces the fruit contain 1,000 to 1,400 seeds remove misshapen fruit that are following year’s production. (research on Hayward). If pollina- unmarketable and to increase the Maturity of wood also seems to be tion is poor, fruit will have inden- size of the remaining fruit. How- delayed by drought, thus increas- tations (narrow valleys) on one ever, it is doubtful whether ing risk of cold injury. However, side or be non-uniform in shape. If thinning is economical in kiwi- too much water also may cause you cut through these fruit, you’ll fruit. Usually, proper dormant production problems. find no seeds in these areas. season pruning balances the crop load. Also, there’s evidence that in Hayward the yield loss due to fruit Table 2.—Kiwifruit leaf sufficiency levels for nutrients. thinning is not compensated for by increased size of remaining fruit. Nutrient % dry weight Nutrient ppm Calcium 2.0–4.0 Boron 25–200 Magnesium 0.20–0.80 Copper 5–15 Nitrogen 2.0–2.8 Iron 60–200 Phosphorus 0.13–0.30 Manganese 50–200 Potassium 1.5–2.5 Zinc 15–30 Sulfur 0.15–0.45

16 Maintaining Your Kiwifruit Vineyard

Pruning and Training early in the growing season. cane that developed from the Fruiting laterals are current permanent cordon. Proper pruning is necessary for season’s shoots that have fruit on Replacement fruiting canes that several reasons: the basal nodes (4 to 6 buds); all originate from the cordon may be • To establish and maintain a the buds beyond the fruit are left to replace older wood in the well-formed permanent frame- capable of producing flower buds future. Fruiting canes should be work for the vine for next year’s crop. separated by about 8 to 12 inches • To obtain a balance between Male and female plants should on the cordon. Head back replace- vegetative growth and fruit be pruned differently when ment fruiting canes to force production mature. growth next season, and tie them • To develop a canopy that uses Female vines. When pruning a to the wires for support. Do not tie available light efficiently (for mature vine, remove about canes too tightly or they’ll girdle photosynthesis), yet is open 70 percent of the wood that grew during the growing season. enough to obtain maximum last season. Most of the wood Spurs (shorter fruiting branches fruit quality and flower bud removed is older wood that with short internodes) often formation for next year’s crop. already has fruited. New fruiting originate from the older wood. Do An open canopy also facilitates canes usually will have developed not remove them unless absolutely harvest and reduces risk of at the base of last year’s canes. necessary, as they are very fruitful fungal diseases such as botrytis. Figure 5 shows a typical fruiting (Figure 5). All species of kiwifruit can be spur pruned in a similar manner. However, there are many different cordon ways to prune a kiwivine. The following description covers the basic techniques. Grower experi- ence may lead to modifications. winter pruning cut Dormant pruning Dormant pruning of kiwivines replacement cane is best done in late December to (headed back in winter) mid-February in the Pacific fruitful shoot Northwest. Late-pruned vines may have excessive sap flow. In kiwifruit, flowers are pro- duced on current season shoots that grow from buds developed on 1-year-old canes (last year’s growth). Shoots that grow from older wood seldom produce fruit in their first season. Shoots from buds that were heavily shaded during the preceding season will be less productive than those from buds that were exposed to the sun. fruitful cane (heading cut made Ideal 1-year-old canes have previous winter) short internodes with well-formed Figure 5.—Mature portion of a kiwifruit cordon in production. Leaves are not buds, and stop growing early in drawn to simplify the figure. Fruit are produced on shoots growing from last the season. These canes develop year’s growth. Winter pruning cuts are shown by . 17 Remove most of the older wood beyond the last flower. Cut back In California, more summer back nearly to the cordon. When watersprouts (vigorous shoots pruning is done on the pergola necessary, you can leave some from older wood), and remove any than the T-bar training system. second-year canes for fruiting tangles. During the summer, However, take care not to exces- wood if 18–48 inches of new vegetative growth can be very sively summer prune as fruit and growth is present beyond where vigorous. Remove shoots not sometimes canes may become fruit was formed last season wanted the following year for sunburned. (Figure 6). Head back these replacement canes and tip replace- Remove all suckers or shoots fruiting laterals to 2 to 4 buds in ment canes to prevent tangling. that grow from the trunk during fuzzy kiwifruit and to 8 to 12 buds the growing season. in hardy kiwifruit beyond where F fruit was formed last year. FF Take care that 1-, 2-, and sometimes 3-year-old fruiting canes are evenly distributed on the F trellis to avoid overcrowding in F any area of the canopy. Remove twisted and tangled growth, shoots that cross from one replacement side of the vine to the other, and cane wind- or winter-damaged shoots. Mature vines, spaced at 15 feet in the row, should have 30 to 45 fruiting canes per vine (spaced at F 8 to 12 inches on both sides). spur Male vines. The goal when pruning male vines is to produce as many flowers for pollination as possible, while keeping the vine manageable. One popular way to cordon prune male vines is to cut most of the canes back to 6 to 12 inches as soon as flowering is finished. New growth during the summer will be replacement cane sufficient to produce flowers for next year. If needed, you can trim the vine during the dormant season.

Summer pruning F In New Zealand, summer pruning begins in mid-spring before flowers open. Remove shoots without flowers that F F originate outside of the wires F (T-bar system). Cut back flower- F ing laterals to four to six leaves Figure 6.—Dormant portion of a mature kiwifruit vine cordon. Winter pruning cuts are shown by . Shoots labeled with an “F” fruited last season.

18 Harvest, Handling, and Storage of Kiwifruit B. Strik ost of the in 4 to 6 days if held at 68–77°F research on (20–25°C) in an ethylene environ- harvest, ment. handling, and A decline in starch content as storage of fruit mature is coupled with an kiwifruitM has been done with the increase in percent soluble solids most common kiwifruit grown (sugars). The increase in soluble commercially, Hayward (Actinidia sugars that begins as kiwifruit deliciosa). approach maturity continues after Although there is a great deal harvest and peaks about when of interest in growing hardy starch hydrolysis is complete. As kiwifruit (A. arguta) commercially fruit mature on the plant, part of in the Pacific Northwest, very the increase in sugars occurs as little information is available the plant produces more carbohy- specific to this species. Most of drate through photosynthesis. the following information relates With advancing maturity, the to the fuzzy kiwi, Hayward. accumulation of carbohydrate However, where information on slows, yet the sugar content hardy kiwifruit is available, continues to increase. At this differences are noted. point, the increase in sugars primarily is due to the conversion Fruit Maturation of stored carbohydrates (mainly starch) to sugars. Kiwifruit Kiwifruit continue to increase contain lots of glucose and in fresh weight and size until fructose and a small amount of harvested, but the most rapid size sucrose. increase occurs the first 100 days At the peak of carbohydrate after bloom. Kiwifruit are one of accumulation, fruit have essen- the few fruits that retain a tially achieved their best potential high starch content at eating quality, and further delays maturity. in harvest will not improve flavor. Starch hydrolysis, Fruit size within a vine is not or breakdown, related to fruit maturity. Also, continues after most cultivars show little visual harvest, even at change in fruit appearance as they 32°F, and is essentially mature. For these reasons, it is completed within a few weeks unreasonable to attempt multiple after harvest. Freshly harvested kiwifruit can be cleared of starch

19 harvests from a vine. Hayward Harvesting Storage tends to have more uniform Once the minimum maturity Store kiwifruit as near to 32°F ripening of fruit within a vine than standards have been achieved, all (0°C) as possible at 90 to do the arguta cultivars of the fruit can be harvested in one 95 percent relative humidity. Even (Ananasnaya, for example). picking. Harvest fruit by hand. To when fruit are held at this tem- Soluble solids (sugar) content harvest fuzzy kiwifruit, pickers perature, about one-third to (°Brix) is the most commonly should wear soft cotton gloves to one-half of the remaining flesh used maturity index for kiwifruit. prevent damage to the skin (fuzz) firmness may be lost per month of In California, Hayward are of the fruit. Fruit are easily storage in Hayward. Fruit are harvested at a 6.5 percent soluble damaged by rough handling even sensitive to freezing injury; be solids standard (6.5 °Brix). Fruit though they seem quite hard at careful that the temperature of the then will attain good quality in this stage of maturity. fruit does not drop below 32°F. storage. Soluble solids content is If arguta fruit are too vine ripe For long-term storage, use of about 12 to 18 percent when ripe. or soft, fruit will tear at the stem controlled atmosphere (5 percent In the arguta cultivars, fruit are end. This is not a problem when CO ; 2 percent O ) has been at about 18 to 25 percent soluble 2 2 harvesting at 8 to 9 °Brix and fruit effective in Hayward, provided solids when ripe. However, to are hard. Do not harvest prema- temperature is kept at 32°F and increase shelf life and facilitate turely softened fruit, as their shelf ethylene-free atmospheres are harvest, this species of kiwifruit is life is very poor. maintained. Note that only bat- harvested between 8 and 9 °Brix Keep fruit in the shade while tery-operated forklifts should be when fruit are very firm. awaiting transport, and cool them used in storage rooms to avoid The soluble solids content of as quickly as possible to maximize generating ethylene. Monitor kiwifruit can be measured with a storage. Field heat must be levels of ethylene in storage on a hand-held refractometer. Cut a removed quickly from fruit after regular basis, because a week or wedge extending from the stem to harvest, because the fruit can lose more of 10 ppb ethylene will blossom end of the fruit and water quickly. After 3 to 4 percent hasten fruit softening. squeeze the juice from the fruit. water loss, fruit may appear Hayward fruit can be stored 3 to Starch in unripe kiwifruit will shriveled, especially at the stem 6 months under ideal storage cloud the solution and make end. This is less of a problem with conditions. Arguta or hardy refractometer readings difficult. A. deliciosa in the Pacific North- kiwifruit, however, cannot be Pour the sample through a few west (compared to California), stored as long, because fruit are layers of facial tissue to clear the because fruit are harvested in more perishable. solution. For a non-temperature- October. To optimize shelf life of arguta corrected refractometer, follow the Softening of kiwifruit also is fruit (e.g., Ananasnaya), harvest at directions for accurate °Brix temperature-dependent—fruit at 8 to 9 °Brix, handle fruit carefully readings carefully. 41°F (5°C) soften three times to avoid bruising, immediately A sample of kiwifruit can be faster than fruit at 32°F (0°C). cool fruit to 32°F, and store them ripened fairly easily to monitor Avoid exposing fruit to ethylene, a at 95 percent relative humidity. ripe fruit soluble solids content, gas that promotes ripening and Fruit should keep for up to but this takes several days. To fruit softening. 2 months under these conditions ripen small samples, place fruit Fruit usually are sorted for size and can be ripened with ethylene. with fresh apples to provide a and quality before packing. If fruit source of ethylene. At 77°F are not packed immediately, store (25°C), ripening will take 4 to them in large bins. 5 days.

20 © 1998 Oregon State University Pacific Northwest Extension publications are jointly produced by the three Pacific Northwest states—Oregon, Washington, and Idaho. Similar crops, climate, and topography create a natural geographic unit that crosses state lines. Since 1949 the PNW program has published more than 500 titles. Joint writing, editing, and production have prevented duplication of effort, broadened the availability of faculty specialists, and substantially reduced the costs for 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, Washington State University Cooperative Extension, the 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, sexual orientation, national origin, age, marital status, disability, and disabled veteran or Vietnam-era veteran status—as required by Title VI of the Civil Rights Act of 1964, Title IX of the Education Amendments of 1972, and Section 504 of the Rehabilitation Act of 1973. The Oregon State University Extension Service, Washington State University Cooperative Extension, and the University of Idaho Cooperative Extension System are Equal Opportunity Employers. Published February 1998 (replaces Oregon publication EC 1464). Reprinted September 2000. $2.50 Ordering instructions If you would like additional copies of PNW 507, Growing Kiwifruit, send $2.50 per copy to:

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© 1998 Oregon State University Pacific Northwest Extension publications are jointly produced by the three Pacific Northwest states—Oregon, Washington, and Idaho. Similar crops, climate, and topography create a natural geographic unit that crosses state lines. Since 1949 the PNW program has published more than 500 titles. Joint writing, editing, and production have prevented duplication of effort, broadened the availability of faculty specialists, and substantially reduced the costs for 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, Washington State University Cooperative Extension, the 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, sexual orientation, national origin, age, marital status, disability, and disabled veteran or Vietnam-era veteran status—as required by Title VI of the Civil Rights Act of 1964, Title IX of the Education Amendments of 1972, and Section 504 of the Rehabilitation Act of 1973. The Oregon State University Extension Service, Washington State University Cooperative Extension, and the University of Idaho Cooperative Extension System are Equal Opportunity Employers. Published February 1998 (replaces Oregon publication EC 1464). Reprinted September 2000. $2.50