Sometimes there are advantages in growing a crop in a new region, over its historical area of supply. Wasabi is an example of this regional advantage.
Wasabi is a perennial herb which grows naturally alongside mountain streams in the highlands of Japan.
Wasabi paste is prepared by grating the fresh stem of the wasabi plant, to form a hot, spicy green condiment served with traditional Japanese dishes such as sushi, sashimi and soba noodles. Ready-to-use wasabi pastes are also popular, and dried powder is used to flavour foods ranging from rice crackers to ice cream. With the inclusion of Asian food in cultures normally dominated by European cuisine, it is becoming increasingly popular.
Wasabi is in short supply in Japan due to a decline in traditional farm labour, urban encroachment on production sites and pollution of some rivers and streams.
Wasabi is grown commercially in gravel beds filled with fast-flowing water or in soil, in a manner similar to other brassica crops.
Wasabi is a cool-climate crop requiring shaded conditions, plentiful irrigation water and readily available oxygen at the root system. The ideal root temperature range of 12–15°C can be a constraint when choosing a site to grow the crop. The requirement for shade and cool growing conditions determines the suitability of a site for wasabi production.
While wasabi tolerates air temperatures ranging from mild frosts to 30°C. The plants exhibit signs of stress and become more susceptible to disease if the root temperature exceeds 18°C. Root temperatures below 12°C cause declining growth rate. Growth ceases altogether at 5°C.
In Japan shade is provided by deciduous trees complemented by temporary shade structures during the summer months. In Tasmania permanent structures, built to withstand windy conditions and using 80% shadecloth, have been constructed. While crops have been produced successfully under black shadecloth, light colours have the advantage of reflecting light, thereby keeping the internal environment of the shadehouse.
The major advantage of producing wasabi in Australia is the ability to supply product year round. Mild summer and winter temperatures in the cool temperate zones of Tasmania and southern Victoria mean that there is no constraint to production as a result of extreme temperatures. In Southland, New Zealand, the crop is able to be grown as an open field crop with none of the much higher costs involved with shade structures and irrigation systems. This generates a significant market advantage to the New Zealanders which they have a history of quickly exploiting.
In Australia there is potential not only to supplement the demand for wasabi in Japan but also to provide fresh wasabi for the increasing number of people enjoying Japanese cuisine throughout the Asia–Pacific region.
Markets in Australia, South East Asia and the Pacific islands will be targeted initially, while increased product volume will provide the opportunity to export to Japan. Current Japanese production is around 5,000 tonnes fresh weight per annum, but fresh product is unavailable in the coldest months (December–February).
Fresh wasabi was not available in Australia or NZ prior to 2000. Processed products imported to Australia often contain European horseradish. Evaluation of wasabi from trial wasabi crops grown in Tasmania has confirmed a large domestic market based in Sydney and Melbourne and export opportunities to South East Asian and Pacific regions with expatriate Japanese populations keen to obtain fresh and processed pure wasabi products.
Since 2000, a supply of fresh Tasmanian wasabi with a farm-gate value of A$100/kg has been available to selected clients in Sydney, Melbourne and Hobart. Fresh stems are air freighted either directly to the restaurant or to a distributor servicing a number of Japanese restaurants. Yields of 10 t/ha have been realised and are expected to double, in line with those achieved in Japan, as crop husbandry practices improve.
