By Chase Mowry, Seed Laboratory Services Manager
Noxious Weed Seed Examinations
Noxious weed seed examinations are one type of test that analysts in seed labs routinely perform. The objective of this test is to identify noxious weed seeds present in a sample and determine the estimated rate of occurrence of said species in the seed lot. This information is to be used for labeling purposes for selling seed as required by seed law. Depending on the needs of a seller, different types of noxious weed seed examinations can be conducted.
Each state has defined noxious weed seed species and an allowable rate of occurrence in their seed law. As well, the Federal Seed Act includes a list of noxious weed seed species. If seed is to be sold within the state, only that state’s noxious species are in effect. When shipping seed across state lines, the federal and receiving state’s noxious weed seed species come into effect. It is the responsibility of seed dealers to know the requirements of state laws and the changes in those laws.
If selling seed out of state, one should request a noxious exam that covers the receiving state’s noxious weed seeds, or request an All States noxious exam. If purchasing seed from another state, one should ask to be provided with documentation that clearly indicates the exam type conducted, prior to making a purchase.
The Seed Regulatory and Testing Division (SRTD), USDA AMS, issues the Noxious-Weed Seed Requirements Recognized in the Administration of the Federal Seed Act publication, which lists the noxious weed seeds in each state and summarizes the states’ requirements. The SRTD updates the publication when informed of changes to state seed laws (the most recent revision was February 2022). This publication, as well as the Federal Seed Act, is available at https://www.ams.usda.gov/rules-regulations/fsa. One footnote of particular interest, listed under prohibited weed seed species for Minnesota, states that genetic testing must be conducted of any Amaranthus contaminant to determine if the species is Palmer amaranth (Amaranthus palmeri).
When exporting seed out of the country, specific noxious examinations based on the destination of the seed lot are also required. The MCIA Seed Laboratory routinely performs Canadian Noxious Weed Seed Exams and EC Other Plant Species Exams on submitted samples as well. As with domestic testing, the results obtained provide necessary seed contaminant information required for labeling exported seed.