DEPARTMENT OF AGRICULTURE

PESTICIDE AND PLANT PEST MANAGEMENT DIVISION

REGULATION NO. 628. SEED POTATO CERTIFICATION

(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 or 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.

(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.

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(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 America, 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 certification.

(m) "Tolerance" means a permissible allowance for a disease, varietal mixture, or grade

defect as specified in the regulations governing the certification of seed potatoes.

History: 1979 AC; 1990 AACS; 1994 AACS; 2002 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.

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

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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 seasons.

(e) The seed lot has been exposed to bacterial ring rot infection before, during, or after

harvest.

(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 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

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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, 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.

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History: 1979 AC; 1980 AACS; 1994 AACS; 2002 AACS.

R 285.628.4a Rescinded.

History: 1990 AACS; 1994 AACS; 2002 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

certification.

(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 certification.

(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 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;2002 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.

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(b) The following visual field inspection or laboratory testing tolerances for diseases and

varietal mix are exceeded during any field inspections or laboratory observations:

FOUNDATION CLASS

NUCLEAR/FY-

CERTIFIED CLASS

FY-1

FY-2

1

THROUGH

FY-5

THROUGH

FY-6

0.50%

1.00%

0.00%

Leaf roll

Mosaics

0.00%

0.25%

0.00%

Leaf roll

Mosaics

Spindle

tuber

Spindle

tuber

Aggregate

B.R.R.

0.00%

0.25%

0.00%

0.10%

Aggregate

B.R.R.

1.00%

0.00%

0.25%

Varietal

mix

Varietal

mix

*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; 2002 AACS.

R 285.628.6 Rescinded.

History: 1979 AC; 1990 AACS; 1994 AACS; 2002 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.

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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 1 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 disinfected.

Nonagricultural equipment shall not be allowed to enter certified seed production fields

unless the equipment is power washed and disinfected. The power washing 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; 2002 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. A certificate of inspection shall accompany each

shipment. Inspection protocols for lot certification shall be approved by the director of the

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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; 2002 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 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 exceeded:

(i) Twelve percent for external or internal defects based on the following allowances:

(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.

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(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; 2002 AACS.

R 285.628.12 Rescinded.

History: 1979 AC; 1980 AACS; 1994 AACS; 1997 AACS.

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.