Sharing Rare Plant Material at the Seed Swap & Scion Exchange

March 1, 2024

By C.J. Walke, Orchard Program Manager

As we approach the end of winter and the beginning of spring, one of our favorite and best-attended orchard events is the Seed Swap & Scion Exchange held near the end of March each year. This year, the event is on March 24, from noon to 4 p.m., at MOFGA’s Common Ground Education Center in Unity, Maine (with a snow date of March 31). This half-day event is packed with talks, presentations, demonstrations, vendors and activities for people of all ages. We will have piles of scionwood from numerous fruit tree varieties and jars and packets of garden seed, as well as other plant cuttings, seedlings, fertile eggs, kombucha starter and many other homemade items. Certainly, it is a day not to be missed!

From the orchard perspective, this is the prime opportunity for fruit tree growers to get their hands on scionwood of desired varieties for grafting but also an essential way MOFGA’s orchard crew can share with the public many of the rare apple and pear varieties we are preserving in the Maine Heritage Orchard (MHO) for propagation and preservation in other locations. All year round we share educational materials and hold events and workshops to spread knowledge of these heritage apple and pear varieties, but this event is our primary means of sharing these varieties for propagation in the broader community.

This year, we are excited to have new additions to the selection of pear and apple scionwood coming from the USDA’s Plant Genetic Resources Unit (PGRU) in Geneva, New York, and the National Clonal Germplasm Repository (NCGR) in Corvallis, Oregon. These two branches of the Agricultural Research Service (ARS) maintain gene banks and clonal plant repositories that represent tens of thousands of variety accessions and hundreds of species of agricultural crops. You may have seen Geneva’s PGRU booth at last year’s Common Ground Country Fair or heard their talk in the Hayloft Tent titled “Conserving American Horticulture.” We are excited to continue this relationship.

Access to scionwood from these repositories is particularly exciting because, by policy, it is not available to the general public for propagation, but reserved primarily for research scientists and professional plant breeders. It is a great honor to be acknowledged in this manner and helps to highlight the importance of our work to preserve heritage apple and pear varieties in the Maine Heritage Orchard. At the writing of this article, we have scionwood of 35 rare pear varieties stored in our walk-in cooler and over 100 apple varieties on the way, all of which are unavailable from our regular scionwood sources and locations.

Most of these varieties will be grafted for cultivation in the Maine Heritage Orchard, or utilized by growers at Fedco Trees or other partners in our preservation and educational efforts. However, we expect to have some scionwood left over and available to share with experienced growers who are serious about the preservation and propagation of these mostly unavailable varieties. We expect to have a designated table for these selections, not part of the general variety mix, so stay tuned for more details as the event draws near.

Another new addition to this year’s Seed Swap & Scion Exchange is a tree sale of MHO apple varieties that we grafted in the spring of 2023 and grew out in our new air prune nursery beds next to the community education department’s farmhouse office on the MOFGA campus in Unity (read more below). We have about 75 rare apple varieties that we grafted a few trees of each onto B118 (Budagovsky 118) semi-dwarf rootstock. Some of these will be planted in MOFGA’s orchards, but many will be available for sale as a MHO fundraiser and to build upon our tree stewardship program. For more information about the stewardship program, please send an email to [email protected] or call the MOFGA office at 207-568-4142.

Air Prune Nursery Beds

I wanted to provide a bit more detail about these air prune nursery beds because they were a new trial for us in 2023, and we have been very pleased with the results. In nursery stock propagation, air prune beds are often used with woody plants that have a long taproot that can be very difficult to dig out of the ground without damaging the taproot. Oftentimes a nursery tree will not survive damage to its taproot or it may be stunted and not very thrifty once transplanted. Air pruning exposes the growing tips of plant roots to the open air, causing those tips to stop growth and send out more root growth higher up, creating a much bushier and robust root system. In vegetable production, soil blocks or Winstrip trays accomplish a similar goal.

air prune nursery bed
The air prune nursery beds at MOFGA are designed to expose the growing tip of woody plants’ taproots to the open air, stopping tip growth and making for easier, less-damaging digging of the nursery stock. Photo by Laura Sieger 

Our air prune nursery beds are roughly 4 feet wide by 8 feet long and 10 inches deep, constructed out of rough-cut pine with a cattle panel and hardware cloth base. The bed is raised off the ground about 18 inches by setting concrete blocks under the corners and the center cross pieces, allowing air to circulate freely underneath. We covered the area beneath with landscape cloth/weed barrier to keep the grass down so we did not have to mow and to maintain good airflow. The beds are filled with very well composted wood chips that had been sitting in a pile for a few years.

air prune nursery bed cover crop
In 2023, the air prune beds were planted with bench grafted apple trees in a 6-inch-by-6-inch grid, and crimson clover was sown as an understory. Photo by Laura Sieger 

We planted the newly bench grafted apple trees on a 6-inch-by-6-inch grid within the bed, which gave us space for about 100 trees in the 32 square feet of bed space. The raised bed made it very easy to weed and monitor from an upright position, and extremely easy to dig the trees in the fall with a common garden trowel. If you’ve ever struggled to dig nursery trees out of the ground, this was a pleasure. And if you want to see the results or learn more about these beds, come see us at the Seed Swap & Scion Exchange on March 24!

This article was originally published in the spring 2024 issue of The Maine Organic Farmer & Gardener.

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