Regulation of Plant Germplasm Imported into the United States1

Abstract

The importation of plant germplasm into the United States involves the risk that certain plant species may carry plant pests hazardous to US agriculture. On the basis of a pest risk analysis, plants or plant parts of a plant species from a particular country are assigned an entry status which constitutes the least drastic quarantine action necessary to exclude hazardous pests that could be imported with this germplasm. Quarantine procedures necessary for entry range from foreign site field inspections (preclearance) or visual inspection at a port of entry (low‐risk seeds) for low‐risk plant material to testing high‐risk introductions for hazardous pests in quarantine facilities (prohibited). The recent revision of Quarantine 37 for the importation of nursery stock reflects changes in the assignment of certain plant genera to either a more or less restrictive entry status on the basis of risk assessments for quarantine pests of the particular genus. Pest risk analyses on certain seeds and also vegetative propagations of grasses, legumes, conifers, and certain fruits and nuts are now underway to determine if future changes in US quarantine laws are necessary to protect US agriculture.

Regulatory Actions to Exclude Pests During the International Exchange of Plant Germplasm

“…Pests that have been isolated and characterized thoroughly can usually be de tected in days with sophisticated serological or nucleic acid detec tion techniques (37). Certain small pathogens that are not as wellcharacterized must be detected by transmission techniques to plants that reliably show characteristic symptoms under a certain range of conditions (17,41,55,57,59). These tests may take weeks if herbaceous plants show reliable symptoms after being rubbed with sap extracts of the imported plant or if indicator trees show leaf symptoms reliably after being grafted with buds from the imported plant.…”