(By authority conferred on the director of the department of agriculture by section 2 of  
1959 PA 221, MCL 286.72)  
R 285.628.1 Definitions.  
Rule 1. As used in these rules:  
(a) "Certifiable seed potatoes" means seed potatoes which meet or exceed the  
standards established in these rules, which are produced and stored as required by  
these rules, and which originate from a state-approved laboratory or greenhouse program  
that involves in vitro techniques of propagation and the subsequent production of  
plants or tubers under a controlled environment.Seed stock produced under these  
controlled conditions shall be designated nuclear. Seed originating from this program  
will be produced in a limited generation system of foundation-field years 1 through 5,  
and certified field years 1 through 6. foundation-field year 1, is the first field progeny  
of nuclear seed produced in a laboratory or greenhouse program. Initial explants  
shall be screened for the presence of pathogens by using accepted techniques.  
(b) "Certification" means the act of verifying compliance with the standards or  
requirements specified in the regulations governing the production of seed potatoes.  
Except as otherwise specified, the measurement method or basis for determining  
compliance with the standards is visual inspection of the growing grounds and  
crops thereon  
harvested therefrom as described in the regulation.  
"Certification" does not constitute a guarantee or warranty or representation that the  
seed potatoes to which the indicia of certification (certification tags, seals, bulk  
certificates) are attached, or which are otherwise represented as certified, are  
merchantable or fit for a particular purpose.  
(c) "Certified seed" means a class of seed which meets the disease and varietal  
tolerances established by these rules for field year 1 through field year 6 and which is the  
progeny of foundation seed or the progeny of seed produced in another state or country  
that is certified as foundation seed or a higher class by an official seed-certifying agency  
in the other state or country using standards comparable to the standards established  
in these  
rules. Certified seed from other states or countries that is to be entered for certification  
in Michigan must meet or exceed Michigan=s certified seed standards.  
(d) A Commercial potato production@ means production of potatoes for other than  
certified seed purposes.  
(e) "Field year" means a seed potato classification designating the number of years  
a particular lot has been grown in the field after greenhouse propagation.  
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(f) "Foundation seed" means the progeny of nuclear seed or a comparable seed class  
approved by the certifying agency. Foundation seed shall meet the disease and varietal  
tolerances established in these rules for field year 1 through field year 5.  
(g) "Nuclear seed stock" means propagation material, including mini-tubers and  
plantlets, which originated in a state-approved laboratory or greenhouse program that  
involves in vitro techniques and which is grown under controlled conditions.  
(h) "Operation" means a seed potato enterprise where the lowest  
class of seed  
planted is certified, field year 6. It includes all land, equipment, storages, and  
facilities used to produce certified seed.  
(i) "Seed lot" means all the seed potatoes of the same variety which are of a single class,  
which are of a specific seed source, and which are harvested from a field or stored  
together in a specific storage facility.  
(j) "Seed potato" means the tuber that is used for the reproduction of the potato.  
(k) "Seed potatoes eligible for certification" means any of the following:  
(i) Any potato variety that has been released, named, and had its description  
published by the potato association of  
United States department of  
agriculture, or a recognized state agricultural experiment station.  
(ii) Cultivars that do not have published descriptions, such as advanced lines from  
breeding programs and protected varieties, if the seed source is approved by the official  
seed-certifying agency and a plant and tuber description is provided to the official  
seed-certifying agency.  
(iii) Lines, selections, and transgenic seed stocks which are derived from previously  
named and described varieties, which enter an approved tissue culture program, and  
which carry a trait or traits that are not visibly certifiable if the lineage is clearly  
substantiated by signed affidavit.  
(l) "Separate operation" means a distinct production unit which has a unique and  
dedicated storage facility and which has equipment that is assigned only to that  
operation. Separate operations shall be designated at the time of application for  
(m) "Tolerance" means a permissible allowance for a disease, varietal mixture,  
or grade defect as specified in the regulations governing the certification of seed  
History: 1979 AC; 1990 AACS; 1994 AACS.  
R 285.628.2 Designation of official seed-certifying agency.  
Rule 2. The Michigan seed potato association is designated as the official seed-  
certifying agency of the department of agriculture for the purpose of assisting and  
advising the department in carrying out the provisions of 1959 PA 221, MCL 286.71 et  
seq. and these rules.  
History: 2002 AACS.  
R 285.628.3 Application.  
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Rule 3. (1) A person may apply for certification of seed potatoes that are eligible for  
certification by filing a written application with the official seed-certifying agency on  
or before June 10 of each year if the operation is located south of highway 55 and on  
or before June 20 of each year if located north of highway 55.  
(2) Separate seed operations may be designated, however, the description of these  
separate operations shall be jointly agreed upon by the owner or manager and the  
official seed-certifying agency at the time of application for certification. Individual  
fields will not be considered separate operations in and of themselves. The owner  
or manager shall submit a separate application for certification for each designated  
operation. Each separate operation shall have a unique and dedicated storage facility,  
and any equipment used in the operation shall be assigned only to that operation  
unless the equipment is power washed and disinfected between operations. The  
power washing and disinfection shall be documented for future reference by the  
official seed-certifying agency.  
History: 1979 AC; 1990 AACS; 1994 AACS.  
R 285.628.4 Conditions for certification.  
Rule 4. (1) A seed lot that is eligible for certification shall not be certified if any of  
the following conditions exist:  
(a) Less than all of the acreage of potatoes grown by the applicant is planted to  
foundation or certified seed that meets Michigan standards and entered for inspection.  
(b) The seed lot is planted less than 5 feet from other potatoes that are part of the  
certification program or less than 50 feet from other potatoes that are not part of a  
certification program.  
(c) The seed lot is grown in a field in which weeds, insect injury, spray damage,  
disease, or any other factor that prevents the adequate inspection or production of  
certifiable seed potatoes is present.  
(d) The seed lot is planted on land used for commercial potato production or that has  
been exposed to infection from bacterial ring rot during the preceding 2 growing  
(e) The seed lot has been exposed to bacterial ring rot infection before, during, or after  
(f) The seed lot is stored, graded, or handled in storage facilities that contain potatoes  
that were not field-inspected or potatoes that were rejected for the presence of bacterial  
ring rot.  
(g) Severe foliar diseases including late blight, early blight, and wilt diseases such as  
verticillium, blackleg, and fusarium; frost injury, or any other condition that renders the  
seed lot undesirable for use as seed is present.  
(h) Bacterial ring rot is present in a seed lot in the operation. All seed stocks of that  
lot are to be removed from the operation. All equipment and facilities that may have  
come in contact with this seed shall be cleaned and disinfected. The first lot of seed cut  
or planted, or cut and planted,  
after the infected lot is not certifiable and is not eligible for sale as certified seed for 1  
growing season. These lots may be retained in the operation in the certified inspection  
system and may be reentered as seed that is eligible for certification the following year  
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if bacterial ring rot is not noted. The classification level for these lots shall be  
retained under the normal generation system as if they were eligible for  
certification. All other seed lots in the operation may be certified, but shall not be sold  
for future seed propagation for 1 growing season. All shipping and inspection  
documents for these lots that are sold during the first year after disease identification  
shall indicate that the seed is not to be used for seed propagation. If bacterial ring rot  
is detected in an operation in more than 1 seed lot in the same year or in 1 seed lot 2 of 3  
consecutive years, then all seed stocks shall be removed from the operation and  
all equipment and facilities shall be cleaned and disinfected before further certification  
will be issued. If bacterial ring rot is detected in an operation in more than 1 seed lot  
in the same year or in  
1 seed lot 2 of 3 consecutive years or noncertified  
production occurred in the previous year of operation, then seed potatoes will not  
be approved for sale or transfer from the operation to other seed propagation operations  
for 2 growing seasons. Cutting and planting equipment is to be thoroughly cleaned and  
disinfected between lots and the disinfection shall be documented for future reference  
by the official seed-certifying agency. This documentation shall be part of the  
application for certification. Materials that are used to disinfect cutting and planting  
equipment shall be of a type labeled for bacterial disease control.  
(i) Seed lots which are eligible for sale or transfer and which have not been winter-  
tested or laboratory-tested or for which a sample or samples have not been submitted for  
winter testing by an organization approved by the official seed-certifying agency or the  
Michigan department of agriculture.  
(j) Bacterial ring rot-infected potatoes and other plant parts that might provide a  
source of contamination or cull potatoes from another location or farm are stored or  
disposed of at, or are introduced into, the operation.  
(2) If a potato disease of significant impact to the seed industry is identified for  
which certification standards have not been established in these rules, then the director  
shall appoint an advisory committee to provide recommendations for appropriate  
certification standards and actions. The committee shall consist of 1 certified or  
foundation seed potato producer and 1 representative each from all of the following:  
(a) The department of plant pathology and the department of crop and soil sciences  
at Michigan state university.  
(b) The official seed-certifying agency.  
(c) The Michigan department of agriculture.  
(3) The signed affidavit required for the genetic material defined in R 285.628.1(j)(iii)  
shall be provided by the applicant to the official seed-certifying agency upon  
request, in order to propagate and certify this material in Michigan. The certified seed  
tag for this material shall specify that it has met all certification standards, except  
for nonvisual characteristics. The plant and tuber descriptions and any required  
affidavits shall be in a format approved by the official seed-certifying agency.  
(4) Except as otherwise specified, the measurement method or  
basis for  
determining compliance with the stated tolerances is visual inspection of a sample of  
the plants or tubers in the field or lot, respectively. Further, except as specified, sample  
sizes are to be determined by the certification agency. Diseases, varietal mixtures, or  
grade defects may be present at a level in excess of specified tolerances; however,  
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disease symptoms, varietal mixtures, and grade defects shall not be visually  
detectable at the time of official inspection due to numerous factors,  
including environmental conditions and varietal differences. Furthermore, even  
the inspection of larger samples might not reveal deviations in excess of specified  
tolerances. Finally, with respect to the zero tolerances for such defects as varietal  
mixture, bacterial ring rot, root knot nematode and spindle tuber, the tolerances are  
chosen for reasons of convenience and practicality and are not construed to mean that the  
lot inspected is free of the defects. Negative inspection results mean that varietal  
mixture, bacterial ring rot, root knot nematode or spindle tuber were not found during the  
inspection process.  
(5) Only seed lots produced from foundation class material or better is eligible for sale  
or transfer for recertification.  
History: 1979 AC; 1980 AACS; 1994 AACS.  
R 285.628.4a Rescinded.  
History: 1990 AACS; 1994 AACS.  
R 285.628.5 Official seed-certifying agency; duties.  
Rule 5. The official seed-certifying agency shall do all of the following:  
(a) Make 2 or more inspections of all fields of seed potatoes eligible for certification  
and all nuclear seed stock eligible for certification.  
An application for such  
certification shall be filed according to the requirements of R 285.628.3. Inspections  
shall be made at times when plant growth and other conditions are optimum for  
varietal identification and disease expression. All potato production shall have at  
least 1 field inspection for ring rot.  
(b) Make at least 1 tuber inspection of all seed lots entered for field inspection  
(c) At least annually and before the establishment of each greenhouse crop, inspect  
storage, laboratory, greenhouse, and screenhouse facilities for proper isolation and  
sanitation. If both greenhouse or laboratory production and the field production are  
inspected by the official seed-certifying agency, then they will be considered separate  
production units. If only the greenhouse or laboratory production or only the field  
production is inspected, then it will be considered 1 unit. Storage, laboratory,  
greenhouse, and screenhouse inspection and testing protocols shall be approved by  
the director of the department of agriculture based on acceptable sanitation procedures.  
(d) Collect, or cause to be collected, representative tuber or plant samples of  
certifiable seed potatoes for winter testing or other tests as may be required for  
(e) Issue certification tags, or bulk certificates for each container or bulk shipment of  
certifiable potatoes or, upon request by an applicant who has sold seed potatoes which  
must be shipped before the winter test results are known and which are otherwise  
certifiable, issue tags or bulk certificates for each container or bulk shipment that  
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contains the statement that the potatoes met summer field and laboratory certification  
requirements but were shipped before the official winter test results were available.  
(f) Apply inspection tolerances to field inspections and winter tests on the basis of  
visual observations, except when deemed appropriate by the certifying agency to  
confirm visual observations or suspected latent infections by analytical methods.  
History: 1979 AC; 1980 AACS; 1990 AACS; 1994 AACS; 2011 AACS.  
R 285.628.5a Nuclear, foundation-field year 1 through 5 and certified field year  
1 through 6 seed lots; certification requirements.  
Rule 5a. Seed lots of nuclear, foundation-field year 1 through 5 and certified seed  
shall not be certified as such if any of the following provisions apply:  
(a) Less than all of the potato acreage on the farm producing such lots was planted  
with seed that had been certified.  
(b) The following visual field inspection or laboratory testing tolerances for diseases  
and varietal mix are exceeded during any field inspections or laboratory observations:  
Leaf roll  
Leaf roll  
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* Any varietal mixture in nuclear or foundation-field year 1 stock shall be rogued to  
achieve 0 (zero) tolerance.  
(c) Roguing is not completed before the second inspection.  
(d) The tuber samples that are winter-tested exceed the disease inspection tolerances for  
virus leaf roll, rugose mosaic, potato virus Y, and spindle tuber, which shall be an  
aggregate of 0.5 for foundation-field year 1 through foundation-field year 5, and 5.0%  
for certified field year 1 through certified field year 6.  
History: 1990 AACS; 1994 AACS.  
R 285.628.6 Rescinded.  
History: 1979 AC; 1990 AACS; 1994 AACS.  
R 285.628.7 Rescinded.  
History: 1979 AC; 1980 AACS; 1990 AACS; 1994 AACS.  
R 285.628.8 Storage  
facilities and equipment; packaging facilities; sanitation;  
isolation of certifiable seed potatoes.  
Rule 8. (1) All equipment and storage facilities shall be thoroughly cleaned and  
disinfected before use.  
(2) Storage facilities, including those located at packaging sites in foundation-field  
year 1 through 5 and certified-field year  
through field year 6 seed are stored, shall  
contain only lots of potatoes that have passed field inspection or have been rejected for  
reasons other than exposure to, or infection by, bacterial ring rot, if the lots are  
isolated from the certifiable seed potatoes. Storage facilities which are  
maintained by the propagator and in which nuclear seed is stored shall contain only  
lots of nuclear seed stock that have passed laboratory or greenhouse inspections.Each  
foundation and certified seed lot shall be separated by a physical barrier that will  
prevent the mixing of seed.  
(3) Agricultural equipment that is used for noncertified potato production and  
processing equipment shall not be allowed to enter certified seed potato storages,  
processing areas, and production fields unless the equipment is power washed and  
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disinfected. Nonagricultural equipment shall not be allowed to enter certified seed  
production fields unless the equipment is power washed and disinfected. The  
and disinfection of equipment shall be documented for future  
reference by the official seed-certifying agency. Materials that are used to  
disinfect storage and production equipment and nonagricultural equipment shall be  
of a type labeled for bacterial disease control.  
(4) Trucks and other means of conveyance which are not owned or operated by the  
seed farm operator and which are used to transport certified seed potatoes from the  
seed farm operation shall not be cleaned on the seed farm premises.  
(5) Packaging facilities and equipment used for certified seed potatoes shall be  
power washed and disinfected and shall be inspected and approved by the certifying  
agency before the facilities are used or the equipment is operated. Materials that are  
used to disinfect packaging facilities and equipment shall be of a type labeled for  
bacterial disease control.  
(6) Storage and packaging facilities that are operated by someone other than the seed  
potato propagator shall maintain grade inspection and bulk shipment certificates,  
certification documents, and other records as deemed necessary by the certifying agency  
for each lot of seed that is stored or packaged at that facility. These documents shall  
be maintained for a period of not less than 4 years after the seed lot has been removed  
from the facility and shall be accessible to the director or the certifying agency during  
normal business hours.  
History: 1979 AC; 1990 AACS; 1994 AACS.  
R 285.628.9 Shipping inspection.  
Rule 9. Each lot of seed shall be inspected for grade at the time of shipping to  
complete the certification process. The inspection may be made by the federal-state  
inspection service or by the certifying agency. A shipping time inspection for grade  
shall be made each time a load of seed potatoes is transferred or shipped, unless, at  
the discretion of the inspector and certifying agency, the lot can be adequately  
assessed and certified by inspecting less than every load based on the fact that a  
representative portion of the lot has been inspected and approved. This overall seed  
lot certification requires an inspection of the initial load shipped from each lot, an  
overall assessment of the lot for uniformity, and at least 1 load for each purchaser.  
certificate of inspection shall accompany each shipment. Inspection protocols for lot  
certification shall be approved by the director of the department of agriculture based on  
the certifying agency's ability to adequately verify the condition of the entire lot.  
History: 1979 AC; 1980 AACS; 1994 AACS; 2011 AACS.  
R 285.628.10 Shipping containers; bulk shipments.  
Rule 10. Seed potatoes, except those shipped in bulk, when sold shall be packed in  
new, clean, unused containers and sealed as required by the certifying agency and  
approved by the director of agriculture. Containers for bulk shipment shall be  
properly cleaned. A certificate for bulk shipment issued by the certifying agency  
Page 8  
shall accompany each shipment in bulk. Seed potatoes for foreign export shall be  
packaged to comply with the requirements of the importing country.  
History: 1979 AC.  
R 285.628.11 Grades and sizes; adoption of standards by reference.  
Rule 11. (1) Grades and sizes of foundation and certified classes  
of seed shall  
conform to the current United States standards for grades of seed potatoes effective  
March 6, 1987. These standards are adopted in these rules by reference and are available  
from the Superintendent of Documents, United States Government Printing Office,  
Washington, DC 20402, at no cost, or from the Michigan Department of Agriculture,  
P.O. Box 30017, Lansing, Michigan 48909, at no cost.  
(2) Blue tag grade seed potatoes shall be in compliance with the requirements  
of the United States no. 1 seed potato grade. The size shall be not less than 1 1/2  
inches and not more than 3 1/4 inches in diameter or more than 12 ounces in weight,  
unless otherwise specified. If stones are present, they shall be duly noted on the grade  
inspection report.  
(3) Yellow tag grade seed potatoes shall be in compliance with the blue tag United  
States no. 1 seed potato grade standards, except that, to allow for variations incident to  
proper grading and handling, both of the following tolerances are permitted:  
(a) The allowance for sprouts may be exceeded after March 15.  
(b) Twenty percent or less of the potatoes in any seed lot shall fail to meet the  
remaining requirements of this grade if neither of the following tolerances is  
(i) Twelve percent for external or internal defects based on  
the following  
(A) Six percent for damage, including not more than 2 3% for serious damage due  
to dry or moist-type fusarium tuber rot.  
(B) Six percent for serious damage due to other defects.  
(C) Total serious damage shall not be more than 6%.  
(ii) One percent for frozen, soft rot, or wet breakdown.  
(4) All sellers and purchasers of a given lot of red tag grade seed potatoes shall  
jointly agree as to size and defects, except that neither of the following tolerances  
shall be exceeded:  
(a) Six percent for damage due to dry or moist-type fusarium tuber rot, including not  
more than 4% for serious damage due to dry or moist-type fusarium tuber rot.  
(b) One percent for frozen, soft rot, or wet breakdown.  
(5) A purple tag shall be used for nuclear seed stock. All sellers and purchasers of a  
given lot of nuclear seed stock shall jointly agree as to size and condition.  
History: 1979 AC; 1980 AACS; 1990 AACS; 1994 AACS.  
R 285.628.12 Rescinded.  
History: 1979 AC; 1980 AACS; 1994 AACS; 1997 AACS.  
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R 285.628.13 Modification of standards.  
Rule 13. The director of the department of agriculture may modify the standards  
established herein for certifiable seed when due to weather, disease or any other  
factor the application of the standards would threaten the normal propagation of  
potato variety.  
History: 1979 AC.  
R 285.628.14 Rescinded.  
History: 1979 AC; 1980 AACS; 1997 AACS.  
R 285.628.15 Rescinded.  
History: 1979 AC; 1980 AACS; 1997 AACS.  
R 285.628.16 Rescinded.  
History: 1979 AC; 1980 AACS; 1997 AACS.  
R 285.628.17 Rescinded.  
History: 1979 AC; 1980 AACS; 1997 AACS.  
R 285.628.18 Rescinded.  
History: 1979 AC; 1980 AACS; 1997 AACS.  
R 285.628.19 Rescinded.  
History: 1979 AC; 1980 AACS; 1997 AACS.  
R 285.628.20 Rescinded.  
History: 1979 AC; 1980 AACS; 1997 AACS.  
R 285.628.21 Rescinded.  
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History: 1979 AC; 1980 AACS; 1997 AACS.  
R 285.628.22 Rescinded.  
History: 1979 AC; 1980 AACS; 1997 AACS.  
R 285.628.23 Rescinded.  
History: 1979 AC; 1980 AACS; 1997 AACS.  
R 285.628.24 Rescinded.  
History: 1979 AC; 1980 AACS; 1997 AACS.  
R 285.628.25 Rescinded.  
History: 1979 AC; 1980 AACS; 1997 AACS.  
R 285.628.26 Rescinded.  
History: 1979 AC; 1980 AACS; 1997 AACS.  
R 285.628.27 Rescinded.  
History: 1979 AC; 1980 AACS; 1997 AACS.  
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