Preliminary assessment of the performance of soil‐grown wasabi (Wasabia japonica (Miq.) Matsum.) in New Zealand conditions

Abstract

Wasabi (Wasabia japonica (Miq.) Matsum.) is a new crop to New Zealand, and nothing is known of its yield potential, growing time, or the husbandry requirements to achieve that potential. As part of an initial assessment, a wasabi crop was grown for 24 months from May 1995 in a shade house at Lincoln to determine how the yield components developed overtime. The crop was sampled monthly from September 1995 to May 1997. Plant numbers decreased from 11 to 7/m² over the time of the trial, mainly as a result of disease. Leaf area indices increased rapidly during the spring to reach full cover in summer and autumn. Stems appeared in December 1995, and increased to 4/plant by November 1996, and then trebled in number over the next three summer months. Much of this increase was the result of the growth of secondary or tertiary stems from buds on the main stems. The high value main stems weighed c. 30–40 g 8 months after planting, and c. 70 g 18 months after planting. By March 1997, only 4 of the 25 stems/m² were over 60 g each i.e., large enough for the Japanese high quality fresh market, and two of these were over 100 g. Up to 5 kg/m² of fresh material were produced in the first year after planting and 6 kg/m² in the second year, and most of this was in the petioles. The crop was hand weeded 9 times and 15 fungicide, seven insecticide, and five slug and snail bait applications were made over the 2 years of this study.