Mount Vernon Northwestern Washington Research and Extension Center

Vegetable Research and Extension

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Wasabi Article

Published in PNW Sustainable Agriculture Newsletter
October 1996, Volume 8, #3, p. 1-3

Carol A. Miles, Ph.D., Washington State University Extension Agricultural Systems, Vancouver, WA   Phone: 360-576-6030; e-mail: milesc@wsu.edu, and Cathy Chadwick, M.S., PO Box 10193, Bainbridge Island, WA   98110, Phone: 206-842-9322.

Introduction

Wasabi (Wasabia japonica (Miq.) Matsum), a member of the Brassicaceae or mustard family, is a staple condiment in Japanese cuisine. Freshly grated, it has a pungent flavor, similar to horseradish, and is commonly served with sliced raw fish, as an ingredient of sushi, or as an accompaniment to noodles.

Market Demand

Current market demand for wasabi roots is strong. Over the last decades, the production area in Japan has decreased due to development and the detrimental effects of rice culture. Concurrently, demand and market value for wasabi have risen. Current research is focusing on the potential for producing wasabi in southwestern Washington for domestic sales and export to Asian markets. On-farm testing and test marketing conducted by Cathy Chadwick, a private consultant working in the area, have shown that wasabi is well-suited to the environment here and the market is lucrative. In regional test marketing in 1996, the wholesale value of individual roots grown in southwestern Washington was $5 and the price per pound was $48. Current yields are approximately 5 tons/A; however yields of 10 tons/A can be expected in an intensely managed situation.

Cultivation

The growth habitatfor wasabi differs from conventional crops. It requires heavy shade, shallow, cold, running water year-round, and thrives in a cool-temperate climate. Water quality should be similar to fish hatchery waters and at least as cold. In nature, wasabi is found growing on shaded, wet banks of mountain streams and springs. In a cultivated situation, a spring-fed area or a diverted stream, which is lined, filled with gravel, and shaded by trees or heavy shade cloth is an ideal site. A constant supply of cool running water and a loose gravel bed are essential for production of high quality wasabi roots. Diverting the stream should prevent flash flooding of the wasabi bed and damage from any debris. Shading the plants is necessary to prevent direct sunlight from burning the leaves, and to keep temperatures below 80 degrees F to alleviate disease problems. Covering the plants prevents freezing, which halts plant growth or may damage the plants’ apical tips, rendering the root unmarketable. Minimal nutrients are required by the plant for optimum yields. In Japan, slow release 12-12-12 fertilizer is added to the water, but excessive nutrients appear detrimental to the crop.

The cost of materials for a wasabi bed measuring 15' X 50' is approximately $1875, not including labor charges and assuming the availability of stream or spring water. The potential return from that one bed after one year is around $3750. Once a site is found to be suitable, a wasabi bed should be earning profits one year after establishment. The real constraint to wasabi production in the Pacific Northwest is the lack of available plant material.

Propagation

Wasabi root is grown fromtransplants and in southwestern Washington takes 12–18 months to grow to optimal market size – approximately 6 inches long and 2 inches in diameter at the crown of the plant. At harvest, remove the entire plant from the bed and trim the root for market. Remove off-shoots carefully at this time and replant them in the bed. In Japan, offshoots are used for three cycles of production, then plant diseases generally make the planting stock uneconomical. A current area of research in Washington as well as in Japan and New Zealand is the propagation of wasabi by both tissue culture and seed.

Tissue cultureof wasabi is likely to be the ideal propagation technique due to its ability to produce disease-free plants. Also, the potential to rapidly produce large numbers of plants for commercial plantings is a major advantage. A major drawback of tissue culture is the heavy bacterial contamination rates common to wasabi and the high costs of overcoming this problem. Losses of 60% are not uncommon. In 1994, experimental micropropagation of wasabi at Washington State University by Steven Potts, in collaboration with Tom Lumpkin, successfully produced 100% disease-free plantlets from peduncle (inflorescence stem) explant material.

Seed production of wasabi is not a well-understood process. Vernalization – cold temperature induction of flowering – does appear to be a prerequisite for flowering, however, optimum temperatures and duration are not known. Additionally, seed viability appears to be low and seeds apparently need cold treatment, or stratification, before they will germinate. Proposed WSU research by a collaborative team of scientists will attempt to address the questions of tissue culture and seed propagation of wasabi.

New Crop Potential

Wasabi has the qualities of an ideal alternative crop for small farms in southwestern Washington. The marketable product sells for a high price, production is limited by strict resource requirements, the petioles and leaves are potentially marketable secondary products, and trade routes to wasabi’s primary market, Japan, are well established. It is not, however, a crop without production challenges. The need for wasabi seedling and transplant production methods is a major challenge that is being met head-on by public and private collaborating scientists and growers. A second challenge is finding farmers who have the water, the patience, and the will to grow wasabi.

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