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The commercialisation of kōkihi or New Zealand spinach (Tetragonia tetragonioides) in New Zealand

N. Roskruge Institute of Natural Resources PN433, Massey University, Private Bag 11-222, Palmerston North 4442, New Zealand

Abstract Kōkihi (Tetragonia tetragonioides) is the traditional name applied to the succulent green commonly called New Zealand spinach. It is a wild plant which grows in localised pockets along the coasts of both the North and South Islands of New Zealand, Stewart Island and Kermadec Island but it is seldom found naturally in inland areas. Commercially kōkihi is not a widely cultivated crop in New Zealand, however it is relatively common in non-commercial gardens and is available in garden centres. Scoping research was undertaken looking at a selection of agronomic factors which apply to this crop in a commercial production system. Kōkihi is susceptible to a minor range of pests and diseases including the fungal diseases Uredo novae-zealandiae (rust) and Helminthosporium sp. (commonly known as silver scurf on potatoes). The relationship of these diseases to other crops will influence the inclusion of NZ spinach in any crop rotation. Management of the plant is otherwise relatively simple and may be well suited to commercial opportunities.

Additional keywords: leafy

Introduction Tetragonia tetragonioides has been given New Zealand is the southernmost the dubious recognition as possibly the only landmass of the Pacific Ocean and of the ‗true‘ vegetable Australasia has provided to Pacific cultures. As such it endures a the world cuisine. This occurred through the relatively temperate climate but does have actions of Captain James Cook and his extremes from sub-tropical in the north to botanist Joseph Banks in their exploits of sub-Antarctic in the south. Māori are the the mid-eighteenth century. Traditionally indigenous people of Aotearoa-New kōkihi was not a cultivated crop by early Zealand and as ‗tangata whenua‘ (literally Māori; however it was occasionally ‗the people of the land‘) they have created harvested from the wild and had several an enduring relationship with the landscape, uses (Roskruge, 2007). Today most including the flora and fauna which consumers of kōkihi source the from survives upon it. Among the plants which small cultivations or home gardens Māori had access to was kōkihi, commonly however, as demand for it increases there is known as New Zealand (NZ) spinach growing interest from horticultural (Tetragonia tetragonioides) which remains producers to include it in their suite of a favoured source for many Māori commercial crops produced for fresh with a variety of uses. markets. It is now being viewed as a

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potential commercial crop option and the Records of the plant being promoted as a seed is also available to home gardeners. vegetable extend back to the first British settlers at Bay (Sydney) of 1788 Botanical status, nomenclature and (Smith, 1998). NZ spinach was illustrated in distribution of kōkihi the 1822 volume (50) of Curtis‘s Botanical Kōkihi or New Zealand spinach Magazine, an authoritative horticultural (Tetragonia tetragonioides (Pall.) Ktze, magazine first published in London in 1787 formerly T. expansa Murr. and including (Matthews, 1977). The first record of NZ the archaic names Demidovia spinach being commercially available in tetragonioides, T. halimifolia, T. cornuta is when London seed suppliers and T. inermis) is native to New Zealand, Flanagan & Nutting offered ‗New Zealand Australia (including Norfolk Island and spinach or Tetragonia expansa‘ in their Lord Howe Island) (Cheeseman, 1925), 1835 catalogue (Smith, 1998). From Japan and the temperate regions of South England, NZ spinach has been disseminated America (Allan, 1961; Haase, 1990), across Europe and is now grown both specifically Argentina and Chile. commercially and as a home garden Tetragonia trigyna (archaically: T. vegetable in many cultures. Information to implexicoma var. chathamica) (Allan, 1961; support the production of this plant can be Haase, 1990) is commonly called ‗climbing found in many countries and languages New Zealand spinach‘ and is closely related including Serbia where it is known as but with smaller and stems (Wall and Novozelandski spanac and where it Allan, 1950). Both plants have prostrate has several synonyms. It is grown habits with leaves that turn red in strong commercially in countries such as Israel, sunlight. The name kōkihi is the preferred where it is also an export crop (Duncan, term now in contemporary usage and is 2004). Prakash (1967) describes the plant as understood to refer to both species across all an annual with a diffuse trailing habit. tribal regions of New Zealand. Kōkihi is It is apparently a relatively common considered as an indigenous vegetable or vegetable in India and featured in the food by many New Zealanders. It is a wild Botanic Gardens of the University of Delhi, plant which grows in coastal areas India. In the USA, NZ spinach is first throughout New Zealand and on off-shore recorded with the distribution of its seed islands including the Kermadecs (Sykes, among members of the New York 1977). Horticultural Society in 1827 followed by The genus Tetragonia includes about 60 its appearance in seed catalogues in 1828 species of flowering plants. They are mostly (Hedrick, 1919). It is both a commercial succulents found in the Southern crop and one that is considered as an Hemisphere, especially South Africa, and invasive weed in some coastal states such as belong to the family. The generic California (Anon, 2008; Stephens, 2003). In name Tetragonia comes from the Greek Central and Latin America, NZ spinach is a ‗tetra’ meaning four and the suffix ‗gonia’ well-known and popular vegetable. It is meaning angles (Wall and Allan, 1950). well suited to the heat of the tropical This is in reference to the shape of the climate and copes with being regularly of the plant which are generally four sided harvested over a long period of time. It is with angular shapes. variously known in each language as NZ

Commercialisation of kōkihi 150 Agronomy New Zealand 41, 2011

spinach (Table 1) and is appreciated for its spinach rather than the native term Tsuruna. minimal management needs. It was It is possible to find NZ spinach on the recorded in the nineteenth century by St menu is such diverse locations as Morocco, Hiliare for its use as ‗spinach‘ in Southern Madagascar, Israel and (Vietmeyer, Brazil (Hedrick, 1919) and is now 1991). commercially grown in many countries of The plant is favoured for its leaves which this region including Brazil and Costa Rica. are used for soups, cooked and stir Tetragonia tetragonioides is also native to fry‘s. Information to support the production Japan and included in the Japanese diet of this plant can be found in many countries although it tends to be referred to as NZ and languages (Table 1).

Table 1: Nomenclature for Tetragonia tetragonioides (Pall.) Ktze (formerly T. expansa Murr.). Nomenclature for Tetragonia tetragonioides Māori (New Zealand) Kōkihi; Paraihia; Tutae-ika-moana; Rengamutu; Rengarenga English New Zealand spinach; sea spinach; perpetual spinach Australian colloquial names Warrigal greens; Warrigal cabbage; Warrigal spinach; Botany Bay Greens; Sydney Greens Polish1 Szpinak Nowozelandzki Norwegian1 Ny-Zealandsk Spinat Italian1 Spinacio della Nouva Zelanda Spanish1 Espinaca de Nueva Zelandia Africaans1 Nu Zeeland Spinasie Hungarian1 Ujzélandi paraj Croatian1 Novozealandski shpinat Russian1 Novozelandskii Shpinat; Tetragonia Shpinatnaia Swedish1 Nyzeeländsk Spenat Greek1 Spanaki Neas Zilandias Servian1 Novozelandski Spanac(h) Slovenian1 Novozelandska Shpinacha Danish1 Newzealandsk Spinat Dutch1 Nieuwzeelandse Spinazie Portuguese1 Espinafre De Nova Zelândia French1 Tétragone; Tétragone Cornue; Epinard; Tetragon German1 Neuseeländischer Spinat German (Switzerland)1 Neuseeländer-Spinat Brazil1; Costa Rica Espinafre Da Nova Zelândia Guatemala (Vietmeyer, 1991) Spinaca Nuevo Zelandia Japanese1 Tsuruna Chinese Xin Xi Lan Bo Cai*; summer spinach; Yeung poh tsoi Philippines (Vietmeyer, 1991) Baguio spinach (Source: the Māori, English and Australian vernacular terms are colloquial; 1www.zipcodezoo.com).

Current agronomic knowledge of kōkihi inhospitable islands such as Women‘s production Island (Johnson, 1976) in the southern sub- Kōkihi grows freely in a wide range of Antarctic ocean. McLuckie and McKee soils and climates primarily aligned to (1962) describe it as one of only a few warm sandy sites including some relatively specialised plants that grows on sandy

Agronomy New Zealand 41, 2011 151 Commercialisation of kōkihi

beaches throughout New Zealand. Kōkihi is Zealand diet. Coincidentally, the resurgent also a native plant in Australia, and interest in niche crops such as kōkihi has generally known as Warrigal spinach; it is raised its potential to contribute to the described as a perennial plant found on the commercialisation of the crop. coast and also inland dry areas but can be grown as an annual in cooler places. Materials and Methods Furthermore, it is described as a plant that prefers temperate to sub-tropical climates, Crop production parameters adapts to hot, dry and sandy soils and resists Trial crops of NZ Spinach were grown salt spray. The plant is suited to a wide during the summer months of 2009-10 and range of soils including ‗poor‘ and saline 2010-11 at the crop unit at Massey soils (Watkins et al., 1988); but prefers University, Batchelar‘s Road, Palmerston alkaline soils with a pH of between 6.5-7.5 North (40°22'40"S; 175°36'27"E) at an and it tolerates maritime exposures. Recent elevation of approximately 35 m. The soils international research has looked at the are a recent Manawatu Silt loam, free tolerance of Tetragonia sp. to saline soils. draining, with a history of vegetable crop Wilson et al. (2000) investigated saline trials including taewa (Maori potatoes) in tolerance at different growth stages of the 2009 and Indian corn in 2007. The plant and determined Tetragonia spp. are preceding crops were monitored for their still sensitive to saline during their juvenile relationship to soil factors and plant health stages, however they gained tolerance as the issues; therefore the site is well understood plant matured. Similar research by Watkins around potential pathogen threats or soil et al. (1988) suggested Tetragonia spp. are limitations. Soil tests results gave a pH 5.8; a marginal halophyte similar to other salt 6.2 and 6.5 respectively in sub-blocks tolerant, non-halophytic plants. within the trial site. All other soil nutrient Kōkihi can establish at any time of the factors were in the median range for year in New Zealand but prefers warm and vegetable production. An additional banded frost-free sites. It is a coastal plant by application of 12:10:10 fertiliser was preference and in some regions such as applied at 250 kg ha-1 during planting. Taranaki is an everyday vegetable, grown in Transplants (40-45 days post-sowing) gardens and harvested on demand. The were planted beginning in late spring each plant can grow up to 1m height and spread season; one trial in each pH sub-block. up to 2 metres. The tips of young plants are Table 2 identifies the parameters applied to preferred for most uses as they are milder in the trials which were based on the limited flavour. By harvesting stem tips plants can information available on their application in be harvested with regularity over the whole a commercially orientated system and the summer-autumn period. Commercial general parameters applied to some other growers harvest the whole juvenile plants as prostrate crops. Observations were a single cut followed by replanting. The undertaken at least twice weekly over a reliability of kōkihi as an available green period of 4 months to determine the growth vegetable plant throughout most of the year habits and demands by the crop that may be has perpetuated its usefulness in the New made in a commercial production system.

Commercialisation of kōkihi 152 Agronomy New Zealand 41, 2011

Table 2: Production notes for Tetragonia tetragonioides. Production factor Notes Planted as transplants: 40-45 days old. very irregular and transplants encourage consistent establishment in-field. Sowing dates 2-3 weekly from early spring Transplants produced for planting out. (September). Planting from 40-45 days as transplants for Single harvest of each plant at approximately one-off harvesting. 50 days from planting (late spring) to 70 days (summer). Plant spacing: in-row 0.5-0.75 m Spacing based on industry norm for bush between rows 0.8-1.0 m. pumpkins which have a prostrate growth habit. pH 5.8-7.5. Alkaline preference, lime as required. Fertiliser: banded application of 12:10:10. To support establishment. Irrigation: applied regularly through summer. Key component of plant integrity and quality. Weed management: cultural and chemical. Stale seedbed method applied. Production season. Market driven - potentially all year.

Results and Discussion meet production demands. Caution needs to be applied however as NZ spinach is noted Crop establishment in many countries as a common weed The natural environment for the plant is species in cropping situations. Currently on warm sandy soils, free-draining and with there is no specialised NZ spinach seed an aspect exposed to the sun for a majority production in New Zealand and further seed of the day. A pH of between 6.5 and 7.5 testing is planned. was identified in the literature (Watkins et Plant spacing can be manipulated based al., 1988; Wallace, 2000; Wilson et al., on harvest systems and also tractor tyre 2000; Stephens, 2003) with the plant width. The plant spacing, both in-row and appearing to prefer more alkaline soils. between-rows, needs to allow for the These trials included a crop at pH 5.8 which prostrate growth habit of the plant and was harvested at the same time as the other access for machinery or harvest. The trials therefore indicating a broader pH parameters trialled were based firstly on range from 5.8-7.5 is possible. Further those applied to other sprawling research on the relationship between soil (primarily cucurbits) grown in summer factors and crop establishment is necessary. months on flat ground and secondly the The seed viability in non-commercial growth rates observed for NZ spinach in the production indicates variable time periods 2009 trial. A once-only harvest of the entire to achieve germination (<20 days) thus plant was undertaken based initially on creating a preference to produce transplants feedback from small producers who for planting out to ensure a consistent single indicated the plant turned woody relatively harvest. Late maturing plants produce an quickly if only partially harvested. This was abundance of seed which, if allowed to supported by production criteria offered by harden and separate from the plant, can be off-shore producers. At 50-55 days post- stored and used in subsequent plantings to planting the trial plants had achieved ground cover and were considered suitable

Agronomy New Zealand 41, 2011 153 Commercialisation of kōkihi

for harvest. As the crop is targeted for a mosaic virus has been associated with T. single harvest there is no need to return to tetragonioides but is not considered an the area several times, thus minimising the economic issue (HEAR, 2011). potential damage to crops through multiple Within New Zealand the primary disease cuttings. At approximately 59-63 days from issue for this crop is the rust fungus planting the first were observed Puccinia tetragonia misdet. renamed Uredo across all trials. This trait is considered novae-zelandiae (McNab, 1966; Dingley, undesirable for the market. The plant 1969; McKenzie, 1998). Tetragonia spp. is flowers and sets easily so late maturing the primary host for this species of rust. plants can be utilised for seed production if Although this disease does not kill the plant, required. rust pustules on the leaves render them unmarketable and unusable. This disease Weed issues was not observed in the trial crop, possibly There are no weed issues of concern for because the plants were harvested relatively producers of NZ spinach other than the early in the season. generic management of production sites to A number of fungal diseases identified in allow the plant to establish its dominance international literature for their pathogenic over an area. The use of the stale seedbed relationship to Tetragonia sp. are present in method for ground preparation supported by New Zealand. These include: Alternaria a pre-emergence herbicide is also alternata (ex: A. tenuis), a storage rot advantageous in minimising weed considered of minor economic importance; competition during crop establishment. As a Botrytis cinerea is a broad spectrum rot; short-term annual plant with a prostrate and sp., a spot fungus; sprawling habit it tends to self-manage Helminthosporium sp., commonly known as weed problems. There are currently no silver scurf in potatoes; and Verticillium agrichemical label claims for weed control alboatrum, a wilt disease found on potatoes in this crop in New Zealand. In fact, most (Duncan, 2004). The association of at least literature and herbicide claims refer to NZ two fungal diseases that are found on spinach as a target weed species rather than potatoes implies good practice for this crop as a crop plant. would be to grow it independently of potato crops rather than in neighbouring land or in Pest and disease issues close rotation. There are few known problems identified International research has identified the with the species however it is known for its field root knot nematode (Meloidogyne susceptibility to a range of viruses including hapla) and glasshouse root knot nematode the Potato Andean mottle comovirus and (Meloidogyne incognita) as parasitic Beet leaf curl rhabdovirus (EPPO, 2011), pathogens of NZ spinach, affecting the both of which have not yet been recorded in roots of the plants in infected soils and New Zealand. Other viruses have been causing ill-thrift, root galls and a loss of mechanically applied to the plant in yield (Duncan, 2004). Meloidogyne hapla is research in several countries resulting in a a recognised parasitic nematode on considerable number of known tamarillo (Cyphomandra betacea (Cav.) susceptibilities, all of which can be tested Sendtner) and kiwifruit (Actinidia deliciosa for in commercial situations. In Hawai‘i the C.F.Liang & A.R.Ferguson) crops (Knight,

Commercialisation of kōkihi 154 Agronomy New Zealand 41, 2011

2001) in New Zealand. This pathogenic commercial systems as it already is in many relationship has been neither observed nor overseas countries and the nutritional and studied on kōkihi in New Zealand at this culinary value can then be exploited in its time however it is worth noting for the native country. The plant is susceptible to implications to producers. only a minor range of pests and diseases Although not observed on these trials, including some rust and leaf-spot diseases. aphids are recognised as a pest on kōkihi, The management of the plant is therefore specifically the melon aphid (Aphis gossypii relatively simple and would benefit from Glover) and Green peach aphid (Myzus good rotation principles. Future research persicae Sulzer), both of which are could target a broad range of factors prevalent in New Zealand (Knight, 2001). including the relationship between soil Heavy aphid infestations can deform leaves conditions (pH, drainage, soil borne and insects can physically contaminate the pathogens) and crop establishment and edible leaf material. The two-spotted spider plant maturity. Factors affecting seed mite (Tetranychus urticae) can also infest production and seed germination need to be this plant and is commonly controlled in quantified. Finally consumer preferences New Zealand using mitacides or through could be evaluated. the use of predatory mites and ladybirds. At least two of the plant health issues References identified indicate a common relationship Allan, H.H. 1961. Flora of New Zealand: between NZ spinach and potatoes (Solanum Volume 1 - indigenous Tracheophyta, tuberosum L.) which in turn indicates some Psilopsida, Lycopsida, Filicopsida, caution should be applied when both crops Gymnospermae, Dicotyledones. are likely to be grown within a crop rotation Government Printer, Wellington. 1085 pp. period or as neighbouring crops. Anon. 2008. Tetragonia tetragonioides. Furthermore as NZ spinach is tolerant of Retrieved on 28 December 2008 from more alkaline soils it may be a useful crop http://www.zipcodezoo.com/Plants/T/Tet to follow winter brassicas which are ragonia_tetragonioides/ generally grown in soils of pH 6.5 or Cheeseman, T.F. 1925. Manual of the New higher. There is no indication that this plant Zealand flora. Government Printer, is susceptible to any soil diseases at the Wellington. 1163 pp. more alkaline pH therefore it would be a Dingley, J.M. 1969. Records of plant useful addition to any rotation incorporating diseases in New Zealand. DSIR Bulletin brassicas at least once in every three or four 192. Government Printer, Wellington. years. 298 pp. Duncan, R.A. 2004. Importation of, New Conclusion Zealand spinach, (Tetragonia In New Zealand, kōkihi is undervalued tetragonioides) Palas., from Israel into and primarily recognised as a home garden the United States. USDA, Raleigh. 9 pp. plant rather than a commercial vegetable. In EPPO. 2011. PQR - EPPO database on general, kōkihi is tolerant of most pests and quarantine pests. Retrieved on 21 diseases in the New Zealand environment October 2011 from http://www.eppo.int and requires minimal input for maintenance. It has the potential to be produced in

Agronomy New Zealand 41, 2011 155 Commercialisation of kōkihi

Haase, P. 1990. Potential plant genetic Smith, K. 1998. Growing uncommon fruits resources of the New Zealand flora. and vegetables in Australia. New Holland Economic Botany 44:503-515. Publications, French Forests, New South HEAR. 2011. Tetragonia tetragonioides. Wales. 164 pp. Retrieved on 21 October 2011 from Stephens, J.M. 2003. Spinach, New Zealand http://www.hear.org/species/tetragonia_te - Tetragonia tetragonioides (Pallas) O. tragonioides/ Ktze., Doc. HS672. Horticulture Sciences Hedrick. U.P. 1919. Sturtevant‘s notes on Deparment, University of Florida. 1 p. edible plants. Report to the New York Sykes, W.R. 1977. Kermadec Islands flora: Agricultural Experiment Station for the an annotated check list. DSIR Bulletin year 1919 II. J B Lyon Company, 219. DSIR, Wellington. 216 pp. Albany, New York State. 686 pp. University of Massachusetts. 2008. New Johnson, P.N. 1976. Vegetation and flora of Zealand spinach. Retrieved on 9 January Womens Island, Foveaux Strait, New 2009 from Zealand. New Zealand Journal of Botany http://www.umassvegetable.org/ethnic- 14: 327-331. crops/crops/new-zealand-spinach.html Knight, K.W.L. 2001. Plant parasitic Vietmeyer, N. 1991. The lost crop of the nematodes associated with six subtropical Kiwis. New Zealand Geographic 10: 64. crops in New Zealand. New Zealand Wall, A. and Allan, H.H. 1950. The Journal of Crop and Horticultural botanical names of the flora of New Science 29: 267-275. Zealand: their origin, history and McKenzie, E.H.C. 1998. Rust fungi of New meaning, with hints on pronunciation. Zealand - an introduction and list of Whitcombe & Tombs Ltd, Christchurch. recorded species. New Zealand Journal 92 pp. of Botany 36: 233-271. Wallace, E. 2000. VGH 2000: vegetable McLuckie, J. and McKee, H.S. 1962. grower‘s handbook, Agro-Research Australian and New Zealand botany. Publications, Havelock North. 223 pp. Horwitz Grahame, Sydney. 758 pp. Watkins, C.B., Brown, J.M.A. and McNab, R.F.R. 1966. Additions to the rust Dromgoole, F.I. 1988. Salt tolerance of fungi of New Zealand - 4. New Zealand the coastal plant, Tetragonia trigyna Journal of Botany 4: 86-94. Banks et Sol. Ex Hook. (climbing New Matthews, B.A. 1977. Illustrations of Zealand spinach). New Zealand Journal indigenous New Zealand plants in of Botany 26: 153-162. Curtis‘s Botanical Magazine. New Wilson, C., Lesch, S.M. and Grieve, C.M. Zealand Journal of Botany 15: 767-773. 2000. Growth stage modulates salinity Prakash, N.1967. Life history of Tetragonia tolerance of New Zealand spinach tetragonioides (Pall.) O. Kuntze. (Tetragonia tetragonioides, Pall.) and red Australian Journal of Botany 15: 413- orach ( L.). Annals of 424. Botany 85: 501-509. Roskruge, N. 2007. Hokia ki te whenua. Unpublished PhD Thesis. Massey University, Palmerston North. 263 pp.

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