For Oregon hemp grower Jerry Norton, the recent harvest season has been successful in more than one way.

Apart from producing a healthy stand of the crop in a Marion County field, Norton is pleased with an experiment on cross-pollination between hemp and its psychoactive relative: marijuana.

The potential for cross-pollination between hemp and marijuana was a major point of contention between growers of the two crops in 2015, which marked the first time in decades that hemp was legally grown in the state.

“There’s a phobia with the cross-pollination,” Norton said.

Marijuana growers fear hemp pollen because they want to avoid the formation of seeds in their crop, which decreases the quality and volume of psychoactive flowers.

As part of his experiment, Norton grew numerous hemp plants in a greenhouse that also contained several marijuana plants. In Oregon, recreational use of the psychoactive crop became legal this year and its medical cultivation has been legal since the late 1990s.

Despite their close proximity to male hemp plants, Norton’s female marijuana plants developed a minimal number of seeds.

“We’ve been successful with them not cross-pollinating,” said Norton.

The dearth of seeds found in the marijuana makes him optimistic that hemp and marijuana growers will find a way to coexist in Oregon, similarly to specialty seed producers who use a mapping system to avoid cross-pollination.

“We want it to be like tomatoes or any other commodity,” he said.

Pollen from marijuana and hemp has been known to travel more than 7 miles, and the plants can be pollinated by honeybees that fly about 2.5 miles from their hives, according to legislative testimony submitted by Russ Karow, an Oregon State University crop and soil science professor.

However, some crops that can technically cross-pollinate — such as goatgrass and wheat — will actually produce few seeds, said Carol Mallory-Smith, an OSU weed scientist who has studied gene flow.

While Mallory-Smith has not studied hemp and marijuana specifically, she said it’s possible that genetic variations and differences in flowering times may be responsible for the low seed numbers seen by Norton.

“There are a lot of biological and physical reasons that plants may not hybridize and produce seed,” she said.

Figuring out which varieties of marijuana and hemp are unlikely to cross-pollinate will require more research to be useful for growers, said Norton.

“We don’t know which can coexist with other ones,” he said.

The issue generated controversy during Oregon’s 2015 legislative session, with a bill that would restrict hemp production passing the House but failing in the Senate.

Hemp production in Oregon has turned out much differently this year than what legislators envisioned when they legalized the crop in 2009, said Lindsay Eng, director of market access and certification programs for the Oregon Department of Agriculture. The crop was legalized several years ago but ODA only began issuing permits this year after finalizing production rules.

While lawmakers expected the crop to be grown on an industrial scale for fiber and seed, Oregon growers are more inclined to produce it on a small scale for cannabidiol, or CBD, a compound that’s thought to have medical uses.

The law requires hemp growers to produce fields of the crop that are 2.5 acres, but it does not set a mandated seeding rate, Eng said. “It doesn’t speak specifically to density, so you could conceivably spread five plants over 2.5 acres.”

The ODA is revising its hemp rules and the legislature may revisit the hemp statute in 2016, she said.

Growers have focused on CBD because it’s more economically viable than competing with large hemp farmers in Canada, Eastern Europe and China, Eng said. “On those industrial-type commodities, you tend to see pretty big acreage.”

Norton said he’s growing hemp for CBD but he also expects that the crop stems to be processed and sold as livestock bedding. The stalks can also be chopped up and mixed with lime to make “hempcrete,” a type of lightweight insulation.

“I think it’s going to be the next thing in building materials,” he said.

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