Seed Testing Program

The Seed Testing Program promotes uniformity and trade in the U.S. seed industry by providing regulatory and unbiased voluntary seed testing services based on the physical characteristics of agricultural and vegetable seed lots.

Regulatory Testing

The Seed Testing Program tests samples submitted by State departments of agriculture, and other seed industry stakeholders, to determine if seed shipped in interstate commerce is correctly labeled. All regulatory testing is performed according to the requirements specified in the Federal Seed Act Regulations.   In addition to laboratory testing, SRTD performs yearly field Trueness-to-Variety (TTV) tests to ensure that interstate seed shipments are correctly labeled for variety.

User Fee Testing

To ensure a wide range of marketing opportunities for U.S. seed stakeholders, the Seed Testing Program maintains a variety of accreditations that allow tests conducted by SRTD to be recognized by seed buyers, organizations, and governments in domestic and international seed markets. 

Clients can request results from seed tests to be provided on one of two certificates issued by the program.

USDA Seed Analysis Certificate – This certificate is the primary document used for regulatory and domestic results reporting. This certificate may also be required for international seed shipments when governments of the receiving country will only accept test results from national seed testing laboratories.  Tests included on this certificate are approved by SRTD botanists that have met all competency-based requirements necessary to earn the Certified Seed Analyst (CSA) designation from the Association of Official Seed Analysts.

International Seed Testing Association (ISTA) Certificates – These certificates are required by many foreign governments for seed imports.  Only ISTA accredited laboratories may issue ISTA Certificates.  ISTA Accreditation verifies whether a laboratory is technically competent to carry out seed testing procedures in accordance with the ISTA International Rules for Seed Testing.  Accredited laboratories must maintain a detailed quality assurance system that fulfills the requirements of the ISTA Accreditation Standard.

SRTD is approved to perform ISTA tests on grasses, cereals, small legumes, pulses, vegetables, and other agricultural crops. The Program’s laboratory may also perform the following test for ISTA: manual sampling; purity and other seed determinations; germination; purity and germination on coated seeds; viability; moisture; and 1000 seed weight.

Types of Testing Performed

The methods below may be performed for both regulatory and voluntary service testing.

  • Physical Purity Test:  Reports the percentages of pure seed, inert matter, other crop seed, and weed seed present in a seed lot.
  • Noxious Weed-Seed Test:  Determines the presence of undesirable noxious weed-seeds. Noxious weed-seeds are determined by following State seed laws and the Federal Noxious Weed Seed List (PDF).         
  • Germination Test:  Reports the percentages of normal, abnormal, dead, and dormant seeds when germinated under ideal conditions.
  • Vigor Test:  Shows the germination potential of a seed lot when the seed is subjected to stress such as heat, cold, or high moisture.
  • Viability Test:  Such as the tetrazolium biochemical test, can detect the presence of dormant seed which may be present if the seed is freshly harvested.
  • Moisture Test:  Reports the moisture content of a seed lot at the time of sampling.
  • Variety Testing:  Includes PCR, electrophoresis, and field trueness-to-variety tests that are compared against a control sample of a known variety.

Monitoring of ISTA Large Seed Lots

The International Seed Testing Association (ISTA) is the only worldwide organization of governmental laboratories dedicated to standardizing quality seed testing across international borders.  The organization consists of member governments from 83 countries/distinct economies.  ISTA was founded in 1924 and the United States government was a founding member. 

The United States and a few other countries have a history of producing very large grass seed lots. Prior to 2012, ISTA required that grass seed lots not exceed maximum lot sizes indicated in Table 2C Part 1 of the ISTA Rules.  This was an issue for seed producers in the United States as it meant that large producers would have to have the same seed lot split and tested twice, costing time and money.  ISTA now allows grass producers to create lots exceeding the maximums listed in Table 2C Part 1 if they can prove to the national authority that those lots are uniform throughout. 

Once approved by the national authority, Production sites wishing to have grass seed testing performed on lots that exceed the maximum lot size must have regular heterogeneity testing conducted to ensure that those large lots are uniform.  ISTA Rules 2.5.4.2 set the monitoring and testing frequency at 6 tests per 100 lots, with subsequent testing requirements being reduced gradually to 2 tests per 100 lots, if all previous tests are in tolerance.

As the ISTA Designated National Authority, SRTD’s monitoring of the approved warehouses consists of the following:

  • SRTD sends a yearly survey to the warehouses on the list, asking them to disclose how many large grass seed lots were produced in the last year.  If any sites reach 100 large lots, SRTD works with the Oregon Department of Agriculture to sample and test the required number of lots for heterogeneity.  All data is submitted to SRTD for approval.
  • SRTD maintains the approved production site list on its website, accessible to anyone. 
  • SRTD has developed a procedure as part of its Quality Management System to describe the entire process.  This procedure is available for review by ISTA, Foreign government authorities, and any grass seed companies wanting to better understand the process.

For more information, contact:

Todd Erickson
SRTD Laboratory Supervisor
(704) 810-8877
todd.erickson@usda.gov

Additional Resources