State of California, Department of Food & Agriculture Division of Plant Industry, Pest Exclusion

Q. C. Circular No. 206

1-5-84

APPROVAL OF FEED GRAIN MILLS & STORAGE FACILITIES

The following is a guide to base approval of feed grain mills and storage areas under the feed grain and seed screenings and cleanings regulations.

An agreement setting forth conditions under which the mill is to operate should be completed, signed by the mill owner or operator, approved and filed with the County Agricultural Commissioner. When a mill is found to be negligent in its operation, it may be necessary to revoke the approval. In such cases, it is desirable to have evidence of a written agreement on file. Notice of action by the Commissioner, either approving or revoking prior approval, should be forwarded to the appropriate District Biologist.

Approved mills should be inspected a minimum of once a year to determine if approval should be continued. Samples from approved mills should be drawn at least twice a year to determine effectiveness of processing. Mills with a history of processing problems should be inspected and samples drawn on a more frequent basis.

The following points should be considered when inspecting a mill for approval:

Unloading Facilities

Truck and rail car unloading facilities differ at each mill or unloading site. It is necessary to evalutate each according to its merits. The unloading or "cut-in-bins" should be located in a favorable location and of a type that will preclude opportunity for restricted weed seeds to be disseminated. This may be a covered area utilizing part of the mill building, or similar arrangement affording adequate protection whenever necessary. All empty trucks or rail cars shall be clean before leaving the mill or unloading site.

Storage Facilities

Bins which have excessive cracks or crevices are not considered satisfactory for clean material when they have been previously used for storage of infested grain or screenings. Bins with a smooth inside surface may be used for storage of clean material after they have been used for storage of contaminated material, provided they are cleaned to the Commissioner's satisfaction after the conditioned material has been removed.

Contaminated grain or screenings should be segregated from clean grain or seed; or all grain or seed in the storage facility is required to be held in quarantine. As a further condition of approving places for storage of material under quarantine, determine that the storage facility can be tightly sealed and require mill management to clean up any weed seed contamination that might be present.

Many mills have operated successfully by using a bin which has been set aside as a "quarantine bin" to receive contaminated grain. Other mills have adopted an authorized treatment for all incoming shipments. Mills which handle booth clean and infested grain simultaneously must satisfy the Commissioner that they are capable of maintaining identity of all feed grain and seed so segregation can be maintained.

Mills may be approved to store infested grain which will ultimately be exported. The commissioner should require safeguards that assure proper handling to maintain continued identity.

Cleaning

Mills designed to remove restricted weed seed pests from feed grain should be equipped with an adequate cleaner. Most mills are equipped with screen or sieve-type cleaners that separate seeds by size and weight. Points to observe during the operation are the rate of feed, variable speed or shake, pitch of the screens, size, and shapes of the screens, amount of suction or air employed, and operation of the tamper, brush, or other mechanisms used to keep the sieves open. Some mills have an additional disc mill to remove weed seeds to meet a zero tolerance.

Grinding - Grain

Hammermills and attrition mills are used to grind weed seed contaminated grain to destroy the viablility of weed seeds. The size of the screen is an important factor in the grinding operation. Most of the restricted weed seed pests found in association with feed grain are of the larger type. A #5 (5/64 inch) screen may be used provided the hammers or grinding mechanisms are not worn. It is possible for worn hammers running at a high rate of flow to push whole seeds through the screen. A #4 (4/64 inch) and a #3 (3/64 inch) size screen are preferable, but the disadvantage of the slow rate of flow and the fine texture of the finished product oftentimes if objectionable to the mill operator.

Grinding - Seed Screenings

Screenings generally require a #3 size screen due to the presence of many of the smaller size weed seeds. The condition of the hammers and screens should be checked periodically.

Heat

Steam heating apparatus must supply an amount of live steam to the grain for the full length of the heating unit to assure a constant mass temperature of no less that 205 degrees F. The heating unit must be equipped with devices which will restrict the flow of grain to assure that all grain is exposed to the minimum mass temperature for no less than 3-3/4 minutes.

Dry heating apparatus must apply an amount of heat within the dehydrator or heating unit to assure a constant mass temperature of no less than 260 degrees F. The flow of material must be regulated so that all grain passing through the dehydrator will be exposed to the minimum mass temperature for no less than five minutes.

Pelletizing Machines - Hay and/or Grain

Hay or grain passing through machines are exposed to the heat for 30 seconds, temperature in the steam jacket should be no less than 190 degrees F. An additional 10 degrees F. will occur when the feed is pressed through the die. The embryo of the seed must attain a temperature of 180 degrees to render it nonviable.

As a condition of approving steam or dry heat processes, the heating equipment should be inspected periodically to determine that the mill meets the requirements. An open-faced thermometer should be permanently installed in the upper half of the steam jacket for the benefit of the mill operator and inspector.

Sampling

Before approving a feed mill, a finished mill product sample should be sent to the Sacramento Seed Laboratory for germination testing and approval withheld until results are received. Additional samples should be drawn periodically.

Form 65-020 should accompany the sample. In "Remarks" section of Form 65-020, for processed material, please request "check for weed seed viability" or "Mill approval-check for weed seed viability"; for unprocessed material (seed that has not been rolled, ground, cracked, pelletized, etc.), request "check for noxious weed seeds" or "check for prohibited or restricted noxious weed seeds" or "check for noxious weeds." Samples should not be submitted in plastic bags and should be submitted without exposing sample to extreme heat or moisture.

Equipment

The following equipment should be available for mill approval: temperature thermometer and crescent wrench, screen gauge, trier probe, sampling bags for laboratory sample, grain dockage sieves, and proper forms.

(End of Q.C. Circular No. 206)