Most nursery stock falls into the last class. A prospective importer must apply to the Department of Agriculture for a plant-quarantine permit before importing the plants. A copy of this must accompany the plants to New Zealand, together with the International Health Certificate set out in the model certificate by the International Plant Protection Convention, 1951, of the FAO in Rome. On arrival at the port of entry the plants are inspected and, if found infested with any pests, are fumigated before being sent to their destination. At their destination most plants are planted into post-entry quarantine and remain there under inspection for any possible diseases for 12 months or more. If at the end of the quarantine period the plants are found clean and healthy they are released to the importer who may then propagate from them or sell them. If disease appears during post-entry quarantine they are either treated or destroyed. The cost of treatment and post-entry quarantine of goods is paid for by the importer.

When plants are considered too dangerous to be imported, they are prohibited, but if it is desirable to introduce a new variety there are special provisions to admit enough to allow for further propagation. Such plants must be grown under strict quarantine under the care of disease specialists.

The 1889 fumigation vaults have been replaced with modern fumigation stations at Auckland, Wellington, and Christchurch, with smaller ones at New Plymouth, Timaru, Dunedin, and Invercargill. Methyl bromide gas is used, either at atmospheric pressure or under vacuum. This gas is the most efficient present fumigant. It kills all stages of the life cycle of pests, without harming most plants or affecting foodstuffs.

by Gordon Arthur Henry Helson, M.SC., Chief Advisory Officer (Entomology), Department of Agriculture, Wellington.