Objective

The primary objective of seed potato certification in Wisconsin and other states is to ensure that the seed potatoes produced by the local industry meet the quality standards mandated by state law.  These standards protect the integrity and reputation of the industry by ensuring that only high quality seed is marketed to growers of fresh market and processing potatoes.  This is accomplished through the certification process in Wisconsin due to its strong, positive impact on:

1. improving productivity and quality of certified seed through elimination of tuber borne disease
2. maintaining varietal type and productivity of Wisconsin clonal selections through visual field evaluation and thorough rouging of off types
3. comparing Wisconsin selections and promising variant clones from other sources under field conditions
4. extending the elite foundation (State Farm) seed program to further improve the quality of certified seed
5. keeping growers informed of current progress on disease control and new varieties
6. promoting wider use of certified seed through joint efforts with the Wisconsin Seed Potato Improvement Association, Inc

• All certified seed potatoes are produced in a limited generation program with a maximum of five generations of propagation.
• Certified seed potato growers must enter their entire potato acreage for certification, and plant all acreage with foundation class seed.
• Only certified seed potato growers with a record of no bacterial ring rot for two consecutive seasons can produce foundation class seed.
• All potatoes entered for certification undergo a minimum of two field inspections and a tuber inspection at harvest or  in storage.
• All potatoes meeting field and tuber inspection standards must be winter tested to be eligible for certified seed tags.
• All potato storage facilities must be inspected and approved prior to filling with certified seed potatoes.
• All certified seed potatoes must be graded in accordance with U.S. seed potato grade standards before official tags can be attached.

Field Inspection Tolerances

Wisconsin seed potatoes are classified as "certified" or "foundation", depending on disease and mixture levels and intended use.  Tolerances for certified class are set to meet minimum acceptable standards for commercial production (see table). Foundation class seed meets much stricter tolerances and is used primarily to plant certified seed acreages.

Field Tolerances for Certified and Foundation Seed Potato Classes in Wisconsin*

*Seed certified in Wisconsin does not exceed the appropriate tolerances listed above based on visual inspections.

The Winter Test

Virus infection of seed lots can and does occur after summer inspections are complete.  A winter grow-out of all seed lots is designed to control the certification of lots contaminated by late-season in-flights of viruliferous aphids.

Winter Test Tolerances for Certified and Foundation Seed Potato Classes*

*Seed certified in Wisconsin does not exceed the appropriate tolerances listed in the above tables based on visual inspections.  Higher tolerances in the winter test are due to the greater likelihood of selecting infected tubers in single-drop seed, as used in this test.

Tag Colors

Two tag colors are used on Wisconsin Certified Seed Potatoes.  The Badger State Brand blue tag meets or exceeds the U.S. No. 1 Seed Potato Grade and the yellow tag represents a second grade with greater tolerances for external defects. Tag color represents grade only.  Seed class (Foundation or Certified) covers disease and mixture tolerances.  The seed class designation is printed on the tag.

The University of Wisconsin College of Agriculture and Life Sciences and the Wisconsin Department of Agriculture, Trade and Consumer Protection make no expressed or implied warranties or representations as to freedom from disease or quality of the seed.  The College and Department expressly disclaim any implied warranty of merchantablility or fitness for a particular purpose and only certify that the inspected plant and tuber samples conformed to the standards for certification and grading.