Identification of weed seeds in soil samples intercepted at the New Zealand border

Identification of weed seeds from overseas countries can be problematic, particularly when diagnostic tools are lacking or incomplete. A well trained seed analyst will usually be able to identify seed to generic level but not always to the species level. Resources for identification of mature plants are usually more complete. Using a seed germination method for intercepted soil samples achieved two goals; it provided an easier route to identification and a measure of viable seed. The drawback of this method is the need to grow the plants through to flowering. DNA identification is an emerging method for more rapid identification, but it relies on availability of matching sequences in an existing database and validation of source plant identification with reliable voucher specimens. The limitations and advantages of both techniques are discussed, and ways in which timely and accurate identification can be provided for biosecurity practitioners are suggested.