Everyone who’s ever been involved in horticultural production has dealt with plant pathogens that have made growing difficult or even impossible. Whether it’s boxwood blight, Phytophthora ramorum or any other organism, the management strategies are multi-faceted. While we often want a quick control for diseases, a better solution is to breed plants that are disease resistant.
That’s exactly what Oregon State University has done with the fire blight resistant varieties of Cotoneaster they have developed in Corvallis, Oregon, under the direction of Ryan Contreras, associate professor of ornamental plant breeding at Oregon State University. I toured their research facility and saw two new cultivars, and I’m impressed by not only the disease resistance but by the lovely forms of these new introductions. Cotoneaster × suecicus Emerald Sprite (PPAF) and C. × suecicus Emerald Beauty (PPAF) are both beautiful plants and are highly resistant to Erwinia amylovora, the bacterium responsible for fire blight.
Emerald Sprite is a highly compact cultivar that is a complete departure from other Cotoneaster cultivars.
“It tops out at 12 inches tall with age, and unlike other dwarfs like ‘Tom Thumb’, this is fast in propagation and production. It roots in a month or less and will finish at No. 1 in 12 months but would mainly be sold in smaller containers that finish much quicker,” Contreras says.
Emerald Beauty, on the other hand, is similar to ‘Coral Beauty’, one of its parents, but is more densely branched and has improved resistance to fire blight. Contreras stressed that it’s not completely resistant, but vastly improved over ‘Coral Beauty’. It has a very uniform branching habit which was clear in the trial plants I saw in the landscape.
Watch for both of these plants to appear in the marketplace in 2020. The patent and royalties are managed by Plant Haven.
Why grow these new Cotoneaster cultivars?
- They are resistant to Cotoneaster fire blight.
- They are easy to grow in ornamental plant production.
- They are improvements over traditional forms of Cotoneaster.
Mark Leichty is the Director of Business Development at Little Prince of Oregon Nursery near Portland. He is a certified plant geek who enjoys visiting beautiful gardens and garden centers searching for rare and unique plants to satisfy his plant lust. firstname.lastname@example.org
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