The U.S. Department of Agriculture’s Animal and Plant Health Inspection Service (APHIS) is altering its rules and regulations on the importation of nursery (garden and landscape) plants into the United States. USDA authority stems from the Protection and Quarantine (PPQ program within the USDA APHIS. PPQ protects agriculture, horticulture and natural resources from the risks associated with the entry, establishment, or spread of animal and plant pests, invasive species and noxious weeds to ensure resilient functional ecosystem services.
The USDA APHIS site explains that "[p]lants for planting can carry a wide variety of pests that are more likely to become established in the United States than pests that could enter through imported fruits or vegetables. The volume of plants being imported into the United States has continued to increase in recent years, as has the body of scientific information regarding emerging plant pests of concern. As a result, APHIS determined the Agency needed to update its regulations in order to better prevent the introduction and establishment of plant pests in the United States."
APHIS formerly has two categories for plant importation: 1) prohibited (not allowed); or 20 restricted (allowed under certain conditions). Now APHIS introduces the category of “not authorized pending pest risk analysis,” referred to as NAPPRA. APHIS has a "list of plants that it considers to be quarantine pests or hosts of quarantine pests. Such plants will not be allowed to be imported until we have completed a pest risk analysis."
"Plants for Planting Whose Importation Is Not Authorized Pending Pest Risk Analysis; Notice of Availability of Data Sheets for Taxa of Plants for Planting That Are Quarantine Pests or Hosts of Quarantine Pests
[USDA will consider all comments it receives on or before September 26, 2011.]"
for more information see Importation of Plants for Planting USDA APHIS site
Lists of NAPPRA Candidates for Host Plants of Quarantine Pests
List of NAPPRA Candidates for Quarantine Pest Plants