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growing a cannabis seed crop

Hemp Crop Standards

GENERAL STANDARDS — The standards on this sheet are in part condensed and apply to Hemp. For greater detail and additional provisions, see the General Standards. All production of hemp is subject to registration, license application and approval by the California Department of Food and Agriculture (CDFA) and the County Agricultural Commissioner in whose county the crop is grown. Only varieties of hemp approved by the California Crop Improvement Association are eligible for certification . The size of an hemp research area or production field may be determined by the regulatory authorities in California.

PLANTING STOCK — In most varieties Breeder seed must be planted to produce Foundation seed, Foundation seed must be planted to produce Registered seed, and Registered seed must be planted to produce Certified seed. Nursery propagation for plants intended for cannabidiol (CBD) production and processing in California will be certified by generations instead of seed classes.

APPLICATION — Applications should be submitted electronically on CCIA’s website (Application to grow and certify seed) as soon as possible and no later than four (4) weeks after planting. New applicants should contact the CCIA office for instructions on obtaining access to the online application system. Applicants must attach to the application the tetrahydrocannabinol (THC) test results of the crop that produced the planting stock or propagules.

FIELD ELIGIBILITY — Crops should not be grown on land where remnant seed from a previous crop may germinate and produce volunteers that may cause contamination. Crops for Foundation and Registered classes of industrial hemp seed must not be grown on land that produced another crop of industrial hemp in the previous 3 years. Crops for Certified class seed must not be grown on land that had a crop of any Cannabis spp. in the preceding 2 years. The presence of Broomrape (Orobanche spp.) in an industrial hemp field shall be cause for rejection (see prohibited and restricted noxious weeds list in the General Standards).

ISOLATION — The area, density, stage of maturity and location of any Cannabis sativa L. plants is an important factor in cross pollination and therefore must be noted in the Field Inspection Report for consideration in determining certification status. There shall not be any Cannabis sativa L. plants within 330 feet of the inspected crop. However, not more than 4 plants per acre of harmful contaminants shall be permitted beyond 330 feet within the isolation distance of the inspected crop. The required isolation must be present prior to flowering and crop inspection.

The minimum isolation distances between a field of hemp and fields of other crops prior to flowering and field inspection are presented in Table 1. If Dioecious male plants within the seed production field start flowering before removal from field, all plants around them should be destroyed for a radius of 10 feet for Foundation and 6 feet for Registered seed crops. All fields or portions of fields intended for certification must have a definite boundary such as a fence, ditch, roadway, levee, or barren strip at least ten (10) feet wide.

Table 1. Minimum Isolation Distances between Inspected Industrial Hemp and Other Crops

– Dioecious variety of Industrial Hemp
– Non-certified crops of Industrial Hemp

– Other monoecious varieties
– Lower certified class seed crop of same variety

FIELD INSPECTION — It is the grower’s responsibility to ensure that the field is inspected by the CCIA field inspector at least once prior to swathing or harvesting, except in the case of Foundation and Registered and Certified monoecious types and unisexual female hybrids, and Foundation dioecious types, in which two inspections are required. Seed from a field that is cut, swathed or harvested prior to field inspection is not eligible for certification.

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Fields must be inspected at a stage of growth when varietal purity is best determined, typically during flowering. Fields not inspected at the proper stage for best determination of varietal purity may be rejected. The first inspection for all classes of monoecious types must be made just before or at early flowering. First inspection for all classes of dioecious types must be made after flowering when male plants are beginning to senesce. Second inspection for all classes of monoecious types, and the Foundation class of dioecious types must be made when seeds are well forming. Isolation areas will be inspected for volunteer industrial hemp plants on each inspection.

Off-Types — Impurities and off-types should be rogued prior to field inspection. Any combination of impurities may be cause for rejection. An hemp crop for Certified Class, unless otherwise specified by the Breeder, must not exceed the limits of harmful contaminants (species that can cross
pollinate with the inspected crop), plants of other varieties or distinct types foreign to the variety being inspected, weeds or other crops with seeds that are difficult to separate from hemp seed (e.g. Hemp Nettle) as outlined in Table 2. The table indicates the maximum number of impurities and off-types permitted by CCIA in approximately 10,000 plants of the inspected crop. A field inspector will make at least 6 counts (10,000 plants each) or the equivalent to determine the number of impurities. The average of these counts must not exceed the maximum impurity standards presented in Table 2.

Table 2. Maximum Impurity and Off-type Standards.

Maximum impurities per 10,000 plants in Industrial Hemp seed crops

Inspected Crop Maximum number of
Dioecious Male
Plants Shedding Pollen
Maximum number of
Off-Types or Other Varieties
Dioecious type – Foundation 3
Dioecious type – Registered 10
Dioecious type – Certified 20
Monoecious type – Foundation 1 3
Monoecious type – Registered 2 10
Monoecious type – Certified 100 20

Weeds — Fields must be free of any prohibited noxious weeds. Restricted noxious weeds and common weeds difficult to separate must be controlled. Prohibited and Restricted noxious weeds are listed in the California Seed Law/CA Code of Regulations/Sections 3854 and 3855. See California Seed Law – Prohibited and Restricted Noxious Weed List.
Fields may be rejected due to unsatisfactory appearance caused by weeds, poor growth, poor stand, disease, insect damage, and any other condition that prevents accurate inspection or creates doubt as to identity of the variety.
A field inspection report will be available online for the applicant. If the field is approved, a certification number will be assigned. This number must be on all containers of seed before they leave the field. It is the responsibility of the applicant to make sure their field has been inspected before it is harvested.

HARVESTING — Harvesting is subject to the supervision of the County Agricultural Commissioner who must be contacted prior to harvest. Any seed moved out of the county for conditioning must be accompanied by an Inter-County or Inter-State Seed Transfer Certificate issued by the Commissioner.

CONDITIONING AND SAMPLING — Conditioning of seed for certification may be done only in facilities approved for this purpose by the CCIA. It is the responsibility of the applicant to determine if the plant is eligible before delivering seed for conditioning. Conditioning, sampling, reconditioning, and
blending will be conducted under the supervision of the County Agricultural Commissioner. Conditioning equipment must be free from contaminating seed to the satisfaction of the supervising inspector.

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SEED INSPECTION — All seed must be sampled and tested after conditioning and the seed lot must meet or exceed seed certification standards for that crop. A seed lab using the Association of Official Seed Analysts (AOSA) “Rules for Testing Seeds” must test the sample. A Registered Seed Technologist must sign each lab analysis. In addition to AOSA rules, specific seed testing may be required to meet CCIA seed certification standards. Applicants must also submit THC test results of the seed crop to CCIA before the Seed Inspection Report is issued.

The conditioner is required to submit a 500 gram sample to the laboratory for analysis. (Submitted Sample Sizes for Certification). In some instances, varietal identity cannot be determined by visual seed inspections. Seed must be well screened and graded, bright in color, of good appearance and meet the following standards:

Pure seed 98.00% (Minimum)
Inert Matter* 2.00% (Maximum)
Other Crop Seed
– Foundation 0.10% (Maximum)
– Registered 0.03% (Maximum)
– Certified 0.08% (Maximum)
Other Varieties
– Foundation 0.005% (Maximum)
– Registered 0.01% (Maximum)
– Certified 0.05% (Maximum)
Other Kinds**
– Foundation 0.01% (Maximum)
– Registered 0.03% (Maximum)
– Certified 0.07% (Maximum)
Weed Seed 0.10% (Maximum)
Germination 80.00% (Minimum)

*Inert matter shall not include more than 0.5 per cent of material other than seed fragments of the variety under consideration.

**Other kinds shall not exceed 2 per lb. (454 grams) for Foundation, 6 for Registered, 10 for Certified.

The CCIA requires Reports of Analysis for initial certification to be dated no more than a maximum of six (6) months prior to the request for seed certification. The ‘Purity Analysis’ and ‘Germination’ must be conducted on the same laboratory seed sample and those results must be presented in a single Report of Analysis.

FINAL CERTIFICATION AND TAGGING — If the seed sample meets all standards a seed inspection report is issued. Before certification is complete, however, each container must have an official tag or label attached. Certified seed may be sold to a grower in bulk without tagging if a properly filled out Bulk Sale Certificate accompanies the shipment. The tags and Bulk Sale Certificates are issued by the California Crop Improvement Association.

Chaff Lining, Seed Mills Aid in Fight Against Herbicide-Resistant Weeds

FAYETTEVILLE, Ark. — The Arkansas Agricultural Experiment Station is taking part in research to fight the battle against herbicide-resistant weeds.

Catching weed seeds before they start a new generation of herbicide-resistant plants is the tactic behind a relatively new method in the United States that weed scientists in Arkansas, Iowa, Kansas and Missouri have partnered to investigate.

“When you take a look at weed management in general, it’s all really centered around soil seed bank management,” said Jason Norsworthy, Distinguished Professor of weed science with the experiment station, the research arm of the University of Arkansas System Division of Agriculture. “If we can drive those soil seedbanks down it’s going to benefit us in terms of the future populations or densities we have in those fields as well as lessening the risk of herbicide resistance evolution and spread.”

The seeds can be caught in the chaff and crushed by a seed mill or laid down in a “chaff line” to consolidate and create a mulching effect, Norsworthy explained.

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Since most of the weed seeds are in the chaff, chaff lining calls for a baffle and chute on the harvester that consolidates the chaff in a narrow row 20 to 24 inches wide on the ground behind the harvester. The chutes can be fabricated by farmers of bought commercially.

Seed crushers do as the name implies, catching the seeds and crushing them. But some seed crushers may work better for different kinds of crops and weed species. That is also part of the experiment station study.

Harvest weed seed control was pioneered in Australia by Michael Walsh, associate professor and director of weed research at the University of Sydney. The method has been widely adopted there to capture weed seeds as they come through a combine during harvest, Norsworthy said. Experiments in Arkansas on chaff lining and seed crushing have been conducted at the Division of Agriculture’s Northeast Research and Extension Center in Keiser.

Prashant Jha, professor of weed science at Iowa State University, showed that more than 95 percent of the weed seeds can be concentrated in a chaff line at the time of soybean harvest during a 2021 study in Iowa funded by the Iowa Soybean Association. Jha, who was a graduate student under Norsworthy at Clemson University, said his studies have shown that chaff lining reduces the spread of herbicide-resistant weed seeds.

The weed seeds that were concentrated into rows emerged four to six weeks later than usual, which allowed the herbicides to be more effective because the weeds were smaller, Jha said. By the time the weeds in the chaff line grew to 2-3 inches, the smaller number of weeds outside the rows had grown to 6-8 inches.

Also taking part in the study is Vipan Kumar, assistant professor of weed science at Kansas State University. Kumar, who was a graduate student under Jha at Montana State University, said his wheat and sorghum chaff lining research in Kansas has shown to significantly reduce kochia and downy brome emergence.

“The mulching effect of chaff lining on weed seed banks further depends on the type of crop being used and the target weed species,” Kumar noted.

Cover crops, various herbicides and seed harvest tactics are part of the multi-level, multi-state experiment on harvest weed seed control, Norsworthy said.

In Arkansas studies on weed seed control, Norsworthy has also experimented with narrow windrow burning. This method collects the seeds in the chaff on the ground, but it is then burned. Norsworthy said his studies showed a 100 percent kill rate of weed seeds using windrow burning, and he has seen some row crop farmers in Arkansas effectively use this method. But he is researching other methods since burning creates issues that include smoke and carbon dioxide release.

After testing narrow windrow burning, Norsworthy tested the Integrated Harrington Seed Destructor. He said it was 99 percent effective in terminating pigweed seeds when the seed mill did not “clog up” in fields with green pigweed plants. Norsworthy is now testing a Redekop Seed Destructor, which he says does not have as much of a tendency to clog on green Palmer amaranth pigweed plants. A desiccate can be used to help dry the Palmer amaranth since the female plants remain green until a winter freeze, he said.

“The end goal is to protect yield potential in fields and reduce the risk of herbicide resistance,” Norsworthy said.