Brown and fuzzy on the outside, a kiwifruit has to be opened to be appreciated – its bright green or gold flesh is attractive and sweet.
Kiwifruit is the fruit of Actinidia deliciosa, a plant originally from China. A vigorous, deciduous vine, it grows to a height of 20 metres. It has large, round leaves 7–12 centimetres in diameter, and bears male and female flowers on separate plants. Male and female plants must grow close together for fruit to form. The fruit is an oblong berry, about the size of a large egg, with coarse brown skin densely covered in fuzzy hairs. Inside, bright green flesh speckled with tiny black seeds surrounds a white core.
Kiwifruit vines planted in New Zealand in the 1930s were still producing fruit in 2008. In Korea, one plant of a related vine, the arguta kiwifruit (Actinidia arguta), is reputed to be 600 years old.
Kiwifruit is most often eaten fresh, although it can be made into juice, purées and preserves, and is used as an ingredient in cooking. The ripe fruit has a slightly acid tang, a bit like a gooseberry. Most New Zealanders consider kiwifruit-topped pavlova to be a national dish.
Kiwifruit has been grown in New Zealand since the early 1900s, but became an important export crop only after the Second World War. The industry boomed in the 1970s but crashed in the late 1980s and early 1990s, when competing countries entered the market. However, with improved production techniques and close attention to environmental issues, along with aggressive marketing, New Zealand’s kiwifruit industry has bounced back. In 2006, kiwifruit was New Zealand’s highest-earning horticultural crop, accounting for 30% of horticultural export earnings.
Kiwifruit seeds first arrived in New Zealand in 1904, brought back from China by Wanganui Girls' College headmistress Isabel Fraser, who had been visiting her missionary sister. She gave the seeds to Alexander Allison, a Whanganui farmer with an interest in unusual plants.
Alexander Allison is credited with growing the first plants of Chinese gooseberry, as kiwifruit was originally known in New Zealand. Its fruit attracted the interest of a number of nurserymen, and by the 1920s plants were being sold at several nurseries. Chinese gooseberries became increasingly popular in the 1930s and 1940s, but remained a novelty crop grown in private gardens and for local markets.
In China, kiwifruit has several colloquial names, including monkey peach, macaque pear, vine pear, sun peach and wood berry. Recently, the name strange fruit, an apparent transliteration of the word kiwifruit, has become common in Taiwan and Hong Kong.
Early horticulturalists selected Chinese gooseberry plants grown from the original seed. Most notable was Auckland nurseryman Hayward Wright, whose vines grew large fruit that kept well and had an excellent flavour. These plants were propagated by grafting and eventually became the preferred cultivated variety (cultivar) for both growers and consumers. In 1956 the cultivar was named Hayward as a tribute. By the late 1960s it was the standard cultivar of the kiwifruit export trade.
The name Chinese gooseberry was changed to melonette, then kiwifruit in 1959 by Auckland fruit-packing company Turner & Growers. Kiwifruit soon became the standard name in horticultural circles. Some countries shorten the name to kiwi.
The green-fleshed kiwifruit was originally given the scientific name Actinidia chinensis, but after an examination of plants in China, botanists renamed it A. deliciosa in 1984. The name A. chinensis was reserved for yellow-fleshed kiwifruit.
In the late 1970s, seeds of A. chinensis were imported to breed new types of kiwifruit. Experiments produced a favourite, ‘Hort16A’, named for its position in the research orchard and the organisation which developed it (HortResearch). In 2000, the cultivar was launched on the worldwide market by Zespri, New Zealand’s kiwifruit marketing company, under the trade name Zespri Gold. The smooth-skinned, yellow-fleshed fruit tasted sweet, with overtones of mango – qualities that have been the key to new Asian markets.
The introduction of gold-fleshed kiwifruit has been a turning point in the industry’s history. It is likely that other, perhaps more competitive, cultivars may be developed, and another breed, Actinidia arguta, has been introduced commercially.
In New Zealand in 2007, just under 12,000 hectares were planted in kiwifruit. By far the greatest concentration of orchards is in the Bay of Plenty, especially near Te Puke. Smaller concentrations are in the Northland, Auckland, Gisborne and Nelson regions.
Kiwifruit vines are fairly hardy and grow in a wide range of temperatures, but to produce satisfactory fruit they need:
The deep, yellow-brown loams of the Bay of Plenty are well-drained, but need regular nitrogen, phosphorus and potassium once the vines begin cropping. Orchards are usually fertilised in spring and early summer with 200 kilograms of nitrogen, 55 kilograms of phosphorus and 100–150 kilograms of potassium per hectare.
Wind is a major limiting factor in establishing a kiwifruit orchard and growing high-quality fruit. Young and flowering shoots are easily damaged, and most orchards need protection from New Zealand’s persistent winds. In the 1970s and 1980s growers planted shelter belts of fast-growing trees, but increasingly they are building artificial windbreaks using polythene fabric.
On the drier East Coast, where annual rainfall is less than 1,000 millimetres, kiwifruit orchards need irrigation in summer. Elsewhere, young vines usually benefit from irrigation.
In winter, kiwifruit vines are leafless and dormant, and can withstand frosts to -10°C. But in spring and autumn, plants are vulnerable to frost damage. Growers use water sprinklers and wind machines to protect their crop if frosts are forecast.
Kiwifruit is grown in orchards that are almost exclusively devoted to the one fruit. This differs from other countries, where kiwifruit is grown along with a number of other fruits.
The average New Zealand orchard is small compared with overseas competitors. In 2006, there were 3,077 kiwifruit growers registered with Zespri. Two-thirds had orchards smaller than 5 hectares.
Vines are grown and trained on supports – either a pergola or T-bar – both of which were designed in New Zealand, but have been adopted as the global industry standard. Vines need to be pruned, otherwise they become a tangle of unproductive, leafy shoots.
The vines are planted out in rows some 3–5 metres apart, depending on the type of support, and with a spacing of 5–6 metres between plants in a row. To ensure pollination, male plants are distributed through the orchard, with male to female plant ratios around 1:5.
Kiwifruit arrived in New Zealand without any of its associated pests, and for the first decades of its cultivation was virtually pest-free. But as the area of vines increased, leafroller caterpillars, scale insects and mites began to attack. Various species of leafroller feed on the leaves and scar the fruit, with the brownheaded leafroller (Ctenopseustis obliquana) the most common. Greedy scale insect (Hemiberlesia rapax) sucks the sap of young plants and can infest the fruit. Kiwifruit with signs of greedy scale are not accepted for export.
Root rots can develop from infection by Phytophthora soil fungi, especially on poorly drained sites. The native bootlace fungus Armillaria novaezelandiae spreads to kiwifruit from infected dead tree stumps or buried wood and causes fatal infections. In humid climates, grey mould Botrytis cinerea rot infects flowers and young fruit.
The bacterium Pseudomonas syringae pv. actinidiae (Psa) arrived in New Zealand on Chinese kiwifruit pollen. First discovered in local vines in November 2010, it had a widespread and severe impact on the local industry, costing several hundred farmers hundreds of millions of dollars.
The kiwifruit year starts after the previous season’s harvest, when the vines drop their leaves and enter winter dormancy. Growers prune fruited and surplus canes. Dormancy lasts until late August, when buds begin to swell. Budbreak, shoot growth and flowering occur in spring. The timing and extent of these depends on how cold winter was – chillier winters usually lead to more profuse flowering. However, prolonged freezing temperatures in winter, and spring and autumn frosts, can harm kiwifruit production.
In early summer, flowers are pollinated and thinned. Kiwifruit are not self-pollinating, so part of each orchard must be devoted to male vines unless pollen is brought in for artificial pollination. Unlike most other fruits, kiwifruit need high levels of pollination (about 13,000 pollen grains per stigma compared to only 12 grains for apple flowers). Growers either place numerous honey-bee hives in the orchards temporarily, or artificially pollinate the flowers.
As well as being New Zealand’s most important horticultural crop, kiwifruit has also become one of its problem weeds. Silvereye birds feed on ripe fruit and spread the seed to bush margins, where the vines grow and smother stands of native bush. Most wild kiwifruit is in the Bay of Plenty, but it has also been found in Canterbury and south Westland – quite distant from kiwifruit orchards.
Throughout summer the main tasks are to remove damaged or misshapen fruit, prune excessive vine growth to maintain fruit health, and control pests and diseases.
Historically, kiwifruit harvesting was timed using a Brix test to determine the amount of sugar in the fruit. Orchardists now also use dry matter and colour tests to ensure harvested fruit has the desired eating qualities. Most fruit is picked in May. Since the mid-1990s, fruit from some early-maturing orchards has been picked for early shipments under the KiwiStart programme.
Fruit is picked by hand and put into bags, which when full are emptied into large wooden bins.
The bins are taken to packhouses, where most of the kiwifruit is graded, packed into trays then placed in a cool store. A small proportion of fruit is kept in bins for cool storage, or in some cases storage in a controlled atmosphere, and is packed later.
Kiwifruit is sold from April to the end of December, with supplies taken out of cool storage near the end of the season.
The first exports of Chinese gooseberries were in 1952–53, from a few orchards in Te Puke, Bay of Plenty. Growers sent trial shipments to the UK and Australia, where the fruit was well received. Early exporters learned by trial and error the complexities of growing, harvesting, sorting, packing and storing a tender fruit for faraway markets.
The overseas demand for kiwifruit grew steadily in the 1950s and 1960s. During this period, kiwifruit producers intensified their use of chemical pesticides, adopted industrial production techniques such as mechanical sorting of fruit, and built large cool stores to hold the fruit ready for export.
Kiwifruit is exported in reefers (refrigerated ships) rather than in refrigerated containers. 1984 was the first year that exporters chartered entire ships for their produce. Since then, Tauranga has become the dispatch port for most kiwifruit exports, which means that the bulk of growers – those in the Bay of Plenty – do not have to transport their fruit long distances in refrigerated trucks to get it to port.
In the late 1970s kiwifruit was hailed as a ‘golden harvest’ because of the industry’s explosive growth. Financial success and the appeal of the orchardist’s lifestyle attracted investors and new growers, and kiwifruit-growing expanded to new areas such as Northland and Hawke’s Bay.
However, unstable interest rates and exchange rates and increased world supplies of kiwifruit led to an industry crisis between 1987 and 1989. Some growers felt bitter that overseas growers were raising kiwifruit from plant stock originally exported from New Zealand – ironically, kiwifruit promoters had created their own competition.
In a tough world market, many exporters competed to sell kiwifruit, driving down the price of the New Zealand fruit. Growers responded by lobbying government to regulate the export sector.
The New Zealand Kiwifruit Marketing Board was established in 1988 and had monopoly powers to distribute and market kiwifruit everywhere except Australia. In 2000 it adopted the corporate identity Zespri International Ltd.
So that it could supply kiwifruit year-round, Zespri began to represent some northern-hemisphere growers and gave them rights to grow gold kiwifruit. The Hayward cultivar is produced to Zespri standards by some Italian growers.
Just as the New Zealand kiwifruit industry was regrouping after the global overproduction crisis of the 1980s, a more severe price crash occurred when European kiwifruit began to enter the market around 1991. It was getting harder to sell to key European markets; in particular, Italian officials prosecuted New Zealand exporters for selling kiwifruit with high chemical residues.
Kiwifruit growers had traditionally sprayed pests (specifically leafroller and scale insects) by the calendar. To meet early export requirements, orchards had to be inspected and declared free of pests and diseases. Before 1992, up to eight insecticide applications were sprayed each season, compared with only one in hot areas such as Chile and California.
Prosecution prompted the New Zealand industry to set up an integrated pest-management system. By 1997, all kiwifruit was produced according to KiwiGreen or certified organic protocols, where biocontrol methods are favoured, and chemical sprays are used only when there are high numbers of pests. The KiwiGreen programme also considers environmental factors, sustainability, ethical trading practices and hygiene standards.
Acknowledgements to Jayson Benge, Bob Martin and Ross Ferguson
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