Enquiries about the requirements to import wasabi stock should be directed to MAF Quality Management. Auckland After planting, the crop is grown for 18-24 months until the stems are a harvestable size. In our trials, the wasabi obtained its nutrients from natural levels in spring water but, in Japan, slow release NPK fertiliser may be added to the water and sulfur sprayed onto the crop to enhance the flavour. Diseases and pests are a major consideration in wasabi production and a current difficulty is that there are no registered pesticides for use on the crop. As a member of the crucifer family, wasabi suffers from the same disease and pest spectrum as brassicas.
Aphids are potentially serious pests because of their ability to transmit viruses.
Wasabi can also be seriously affected by tobacco, turnip and cucumber mosaic viruses. Root aphids have also been found on wasabi roots and, while the pest is not widespread, it is likely to be difficult to control. At harvest, wasabi plants are broken up by hand to extract the exportable stems. For export, the stems should be green and have little discolouration from Phoma infection. The leaf stalks are trimmed to one-third the length of the stem.