The moist and moldering days of fall are upon us: wet leaves trodden into the soil, fleshy fruits turning to muck in the garden. These are weeks of surrender and senescence, although in another sense, these are weeks ripe with potential. It makes me think fondly of children’s books that I grew up with, featuring chattering, well-dressed mice who carefully stored crabapples and sundry seeds for the winter, warming their homes with thistledown carpets. At the Arnold Arboretum, these fall fantasies are vivid in the Bradley Rosaceous Collection, a garden where bare thorny stems suspend red and ready fruit and where the leaves that remain are largely shades between gold and rust.
While, of course, apples (Malus) are among the classic signs of fall—and some of the newer apple additions in the Bradley orchard, beyond the beds of rosehips and brambles, have borne their bounties this year—a more unusual plant, the oriental photinia (Photinia villosa), is taking the showstopping prize of the season. The Arboretum has nearly two dozen specimens of this species, representing wild provenances from across its range in China, Korea, and Japan. The plants, while never more than 10 or 15 feet tall, come in various shapes. Some have tangled limbs and wouldn’t look out of place in an English hedgerow—trees with a handsomely disheveled look. Other specimens, especially several accessions from southern provinces of South Korea, are among the sturdiest in the collection, with single upright stems and architectural crowns. I’m especially drawn to a grove of three (accession 934-85) that arches over one of the paths in the garden. The leaves on these southern South Korean plants are larger and have remained green, even while many of the other accessions have already blushed orange and peach, and the leaves are unmarked by serious disease or insect damage. Moreover, the abundant fruits on these plants are as bright as cherry jam.
Photinia occasionally earns a luckless reputation in horticultural circles, given its susceptibility to fire blight (Erwinia amylovora). This bacterial pathogen causes leaves and shoots to wither and blacken, and if unmanaged, it can cause the most serious symptom of all—plant death. Special care must be taken if the infected branches are removed during the growing season, given that pruners must be sterilized with isopropyl alcohol or bleach between cuts. Winter pruning is recommended. The Arboretum’s photinia are healthy, however, and Scott Phillips, the horticultural technologist who oversees the Bradley, reported that the trees haven’t required special treatment or attention, other than the same cultural care that generally promotes health in the collection. Among the fall tasks, Phillips has been removing leaf litter to prevent disease buildup in the beds.
For that matter, the Arboretum has cultivated around 60 specimens of Photinia villosa over the last 148 years, and only three cases of fire blight damage have been reported in the plant records. Two cases were minor, and only one was severe enough that the tree was removed, in the 1990s. Undocumented cases doubtless occurred, even in instances where the plants were removed for unspecified “poor condition,” although the absence of specific references in the records may suggest that a serious situation never swept through the collection. Perhaps photinia’s disease-prone reputation, at least locally, isn’t altogether warranted. Or perhaps some of these lineages, like the robust specimens from South Korea, are more resistant than others.
If fall is the season of stocking cupboards and root cellars—at least for storybook mice—ornamental gardeners share in that sense of forward-looking optimism. The horticultural groundwork for the following year is already underway. Summer weeding is done, and we head out with our rakes and our baskets. Compost and soil amendments may be spread in the beds. While we are in no rush for the pending cold and frost, we sharpen our pruners for the dormant season ahead. Fall gardening is about doing everything possible to make sure that nothing gets in the way of the spring flowers and green flush, no matter how distant those scenes may seem.