How genetically modified greens could affect Canadian organic seed producers
By Bob Wildfong, Executive Director, Seeds of Diversity Canada
March 2025
Seeds of Diversity’s main concern with genetically modified vegetables is the possibility of cross-pollination between seed crops, which could undermine Canada’s organic seed supply. Certified organic seeds are a crucial part of our future food sustainability, since the best organic food is grown from organic seeds, and Canadian-grown seed is the best adapted to our local growing climates.
For seeds to be certified organic, they must be produced by a certified organic grower, just like food. If a farmer can produce certified organic food, they can also produce seeds to be labelled organic, except the seeds must be free of any genetic contamination from GMO pollen.
The risk for certified organic seed producers is that GMO greens might be grown nearby, and allowed to flower (on purpose or unintentionally), allowing pollen to cross-pollinate the organic seed crop. This would make the seeds unusable as organic seeds, and harm the seed producer’s business and livelihood.
How far away does the GMO crop have to be to prevent cross-pollination?
The problem with GMO crops and organic seeds is that the isolation distance has to be extremely large, and often impossible to achieve. For seed savers familiar with isolation, it’s the distance that two crops of the same species have to be separated so that pollen won’t reach from one to the other. Even in normal seed saving, we keep crops isolated so they don’t genetically inter-mix, which would create hybrids. After all, we don’t want heirloom varieties to cross-pollinate with each other either, so isolation is a normal requirement.
The problem is the degree of purity, which governs the degree of isolation.
Mustard (Brassica juncea) and related greens have heavy, sticky pollen so they have to be pollinated by insects (instead of by the wind) so the distance we have to separate our seed crops is based on how far those insects might fly. In most cases, a few hundred meters is enough, but there will always be a little crossing, which decreases the further you separate the crops.
Various studies of B. juncea cross-pollination (summarized here) reported crossing at distances from 35m up to 400m and occasionally as much as 800m. The simple reason for the large differences in distance is that insects can travel short or long distances depending on food sources, physical obstacles such as roads and trees, and even just the way the wind is blowing.
The Canadian Seed Growers Association publishes requirements for commercial seed production. Their Circular 6 – Regulations and Procedures for Pedigreed Seed Crop Production sets the required isolation for commercial seed crops of mustard (B. juncea) at 200m. Obviously, this is less distance than the pollen can travel by insects, but as with all isolation distances it is a compromise between seed purity and practicality.
Isolation distances are rarely set to achieve 100% genetic purity of seeds. The reality is that there will always be occasional crosses over large distances, so seed growers must balance seed quality against the practicality of achievable isolation distances. The standards are designed to create seed purity of usually greater than 99%, but not perfect.
The problem for organic seed producers is that no amount of GMO contamination is accepted in certified organic seeds. Even a trace can mean the difference between a profitable and sustainable organic seed harvest and the complete loss of a whole year’s effort and expense. This will place a hardship on organic seed farmers to make much more extreme efforts in their seed crop isolation than other seed growers must do.
That’s why we are actively alerting organic seed producers that their plans for certified organic mustard and related greens might be threatened by a new planting of GMO greens a field away, even by a grower who might not realize that they’re even planting GMO greens.
What can you do?
The good news is that you can always be sure that your seeds are GMO-free if they’re certified organic. You can support non-GMO vegetable seeds, and our local organic seed producers, simply by purchasing Canadian-grown certified organic seeds.
That’s a win-win solution for us all!
This is a developing issue, and not a lot of details are known yet. Pay close attention to the brands of seeds that you purchase this year, and check back with CBAN’s web site for more news.cban.ca/GMOsalad
Bob Wildfong has been saving seeds and teaching about garden biodiversity for over 30 years. He mixes science and storytelling to reveal the secret lives of seeds, plants, and pollinators. Bob has been a member of Seeds of Diversity since 1988, and became our first Executive Director in 2002, after a career in software engineering. He teaches garden and food history at the Waterloo Region Museum, and as a board member of the Pollinator Partnership Canada helps build the movement to preserve pollinators. He is a past president of the Culinary Historians of Canada, and delights in explaining how we can learn about future food sustainability by remembering past lessons.
Seeds of Diversity Canada is a group of seed savers from coast to coast who protect Canada’s seed biodiversity by growing it themselves and sharing it with others. Every year, they multiply the most vulnerable seed varieties that they can, exchange seeds with each other, and keep those varieties alive and in cultivation for future gardeners to enjoy. They are a membership organization with over 3000 members across Canada that make Seeds of Diversity a vibrant and visible part of the gardening and food security scene. Their funding primarily comes from charitable donations made by both members and non-members. Besides multiplying rare seeds, they volunteer at over 150 Seedy Saturday and Seedy Sunday events across Canada, write articles for their popular monthly email bulletin, package seeds for community seed libraries, and help beginner seed savers learn the easy techniques for growing good seeds.
Updates: cban.ca/GMOsalad
