Keep 'em separated: Cannabis, hemp cross-pollination problem blows into California regulation

Now that it is legal at a federal level to grow hemp with the passage of a federal farm bill last year, California and its counties are struggling to write rules regulating production.

But one of the most pressing issues could be keeping fields that grow hemp, a type of cannabis, separate from stands of marijuana, also cannabis and known for its mind-altering qualities unlike hemp.

Last month the Mendocino County Board of Supervisors voted to implement a temporary moratorium on hemp cultivation, citing among other issues concerns about the cross pollination with marijuana, cannabis plants containing the psychoactive compound THC.

Sonoma County has similar concerns, according to county agricultural commissioner Tony Linegar.

Under federal law, farmers can grow hemp as long as the plants contains less than 0.3 percent tetrahydrocannabinol, or THC, the psychoactive ingredient that creates the 'high' associated with the cannabis plant. Hemp typically contains only trace amounts of the chemical. It can be harvested for fiber for clothing but is increasingly prized for its cannabidiol, or CBD oil, which is touted as having a variety of health benefits including stress and pain relief, to name a few. Farming for the oil rather than the fibrous stalks also requires less acreage, Linegar said, noting that could be a plus in Sonoma County given the expensive price of real estate and potential competition with the wine industry.

With the growing demand for CBD, Linegar also said hemp seeds could become more valuable and that Sonoma County could become a prime producer of approved, low THC strains.

The ordinance adopted by Mendocino County also noted that the state had not yet approved seed sources for hemp and said unregulated seeds could carry disease.

CBD is of dubious legality, however, according to Linegar, who noted the state health department has prohibited the chemical from being added to food products despite it being widely available.


Issues of cross pollination occur because 'cannabis is what we call a dioecious plant,' Linegar said, meaning that male and female features, seeds and flowers, occur on different plants instead of the same one.

Female marijuana plants produce flowers which farmers grow for their THC content, but if male hemp plants, which are largely grown for their fibers, are planted too close to female plants, the hemp can pollinate the female marijuana plant. That can cause them to seed and impact their yield and THC content through the sharing of genetic information, Linegar said.

'If they're near a [hemp] farm that is producing male plants, particularly farms producing plants for fiber, that really devalues the bud,' he said, referring to the marijuana flowers.

The issue could also arise between male and female hemp plants as well, according to Erica Stark, executive director of the nonprofit National Hemp Association, a Washington, D.C. based advocacy group.

'The cross-pollination issue affects the hemp industry more so in the cross pollination between fiber and grain varietal of hemp and CBD varietals of hemp,' Stark said. CBD varietals are female and if planted too closely to plants prized for their fiber could be pollinated and 'would greatly reduce the value and the yield and the overall profitability,' she added.

Regulations for testing and permitting are currently under consideration at the state and county level and would have to include specifics on how far hemp and marijuana plants could be from one another, said Linegar.

'I've read from three miles to 30 miles, with the consensus sort of being that 10 miles is a safe distance between the two crops to ensure no substantial level of pollen drift would take place,' Linegar said of the necessary separation.

Stark said her group advocates for research into if staggered planting of fiber and CBD hemp plants so they mature at different times could avoid the problem.

Regulation writing is already underway at the state level with the state legislature's passage of SB 1409 last year creating a program in California for the regulation of hemp.

Linegar said that the registration process for hemp producers, including what information county agricultural commissioners have to collect from farmers, had already been developed and was going through final approval at the state Office of Administrative Law and would likely be finalized within a month.

Counties can make their own local regulations around hemp or adopt state policies, Linegar said. He added he expected to present information to the Sonoma County Board of Supervisors on the issue, including pollination concerns, in the near future.

Regulations for testing the hemp to insure it had the properly low THC level as mandated by Congress also had to be developed, he added.

Linegar said the size of the potential market in the county was unclear but the main attraction of planting hemp in Sonoma County would probably be CBD production.

Staff Writer Chase DiFeliciantonio covers technology, banking, law, accounting, and the cannabis industry. Reach him at or 707-521-4257.

Editor Note: This article was changed to clarify fiber hemp varietals can be male or female. There is a concern CBD hemp varietals, which are all female, can be pollinated by hemp fiber varietals, which are male and female. While only male and not female fiber plants can pollinate the female CBD plants, fiber plants come in both genders.

A second change recharacterizes research Stark and her group advocate, which is into the staggered planting of female CBD hemp plants and fiber plants, which can be both male and female, and not just of male and female plants.

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