Robert asks whether the kind of experimentation, diversification and exchange that might be fostered by making it easier for people to swap seeds requires some sort of risk control. My simple answer is “I don’t know”. Fungi, bacteria and viruses can all hitch a ride on the outside of the seed, inside the seed coat, and in some cases within the tissues of the seed, and several can be a really bad problem. Many growers control the risk by treating seeds with fungicides and other chemicals. Organic growers have developed other kinds of treatments, including carefully controlled hot water baths. I think there are two problems.
First, will you introduce a new disease to your own plot? Quite possibly, and only you can decide whether that is worth the risk, and what steps you are willing to take to prevent it.
Secondly, will you introduce a new disease to your region or, as Robert puts it, “spread devastating plant diseases across the globe”? This, naturally, is much harder to answer. I’m inclined to believe that individuals swapping seeds pose no greater threat than industrial and government activities, but that is very much a gut feeling. Pests and diseases do slip past almost every control system, although seldom is it possible to pinpoint the specific occasion on which it happened.
Phytosanitary legislation aims to minimize the risks, but I have no idea whether there are exceptions for small quantities, as there are for some other seed laws. Perhaps a reader can enlighten us.
People may want to take precautions before sending or receiving swapped seeds, but I wouldn’t rely on that (or anything else) to protect the world from seed-borne diseases.
Right now we’re preparing our seeds for the Winter Nursery in Mexico, and as part of the process, we include one seed from each row we’re planting in a “Bulk” bag for testing purposes.