Changing Conditions and Plant Quarantines.

Since 1880 refrigeration has made it possible to transport living plants across the tropics, but they have been accompanied by the diseases which previous introductions of seeds had excluded. More than 500 fungous, bacterial, virus and physiological diseases of plants have been recorded in New Zealand. Of these 150 are endemic on native vegetation and 350 have been introduced. Some were brought in with nursery stock, in bulbs, corms, tubers, cuttings or other vegetative parts that were imported specifically for planting and propagation. Others have been introduced in vegetables or discarded vegetable refuse of visiting vessels, and the remainder probably in commercial seeds used in agriculture, horticulture or forestry.

Today we are in the era of air transport which permits transport of plant material, plant diseases and insects that could not survive the transport by the slower sea routes and we are faced with the danger of introducing such pests as the Mediterranean fruit fly, and new strains of parasitic diseases that are more virulent than those that are at present in the country. The position calls for a new approach to the problem of preventing further invasions of such scourges as the white butterfly, citrus canker, onion smut and other plant pests and diseases which have crossed the ocean to our shores in recent years.