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Disease has many seeking alternatives to dogwood trees

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IN THE GARDEN by JENEEN WICHE/Garden Columnist

The beacon of spring in these parts is undoubtedly the native dogwood.  But, because of disease problems, especially dogwood anthracnose, people are seeking alternatives to Cornus florida.  There are other notable dogwoods like Cornus kousa and Cornus mas, but look beyond the dogwood for small, spring flowering landscape trees that prove to have interest well into summer. Consider the Carolina silverbell (halesia) and the fringe tree (chionanthus).

Both trees are native to the southeast United States and are well-suited to Kentuckiana’s climate.  They are perfect for home landscapes because they are small-growing.  The Carolina silverbell is a tree that reaches about 30 to 40 feet in height with a spread of 20 to 30 feet.  The fringe tree is a small tree or large shrub (depending on how it is trained) that reaches about 15 to 25 feet in height and 10 to 15 feet in spread.

The Carolina silverbell, Halesia tetraptera (sometimes listed as H. carolina or H. monticola, the mountain silverbell) is a perfect alternative to dogwoods because it is ideal as an understory tree, preferring cool, moist and acidic soils.  Single-trunked trees have a pyramidal to rounded canopy while multi-trunked specimens usually develop a lower branch profile creating a more rounded appearance.  Their blooms, bark and fruit combine to create seasonal appeal.

The blossoms of the Carolina silverbell are white, bell-shaped flowers that appear along the branches in April and May, just before the leaves emerge.  Often, however, they are still blooming as the leaves break dormancy on the tips of the branches.  The flowers make for a dramatic display in their own right, but the mass of white with little hints of green throughout is especially nice on a spring day.  

The fruit of the Carolina silverbell ripens to a pale green color in early fall.  Instead of flowers lining the branches you can now enjoy the fruit that has four distinct wings, reminiscent of little lanterns.  Silverbells are not known for their fall color, so enjoy the fruit and the bark which matures to a smooth gray with darker gray striations.

Chionanthus virginicus, or the fringe tree, is generally found as a multi-trunked shrub, however it can be grown as a single-trunked small tree.  I prefer them in the shrub form because of their natural growth habit, rounded and spreading, which make for a better display of the fleece-like white panicle blooms that cover the shrub in May and June.  If you prefer a tree form, simply limb the plant up about 6 to 8 inches a year.  Chionanthus bloom on last year’s wood, so when you do pruning, do so immediately after they finish their bloom period to avoid removing blooms unnecessarily.

Chionanthus is one of my favorite plants these days because of its beauty, but also because of its adaptability.  It’s cold hardy to -30 F and drought tolerant.  It will do well in full-sun to part-shade, although the foliage holds up better through hot summers if it is shaded in the afternoon.  Despite its drought tolerance, chionanthus prefers moist, acidic and well-drained soil.

Fall color is a straight-forward yellow to yellow-brown, but the fruit provides interest during late summer and into fall.  Clusters of oval blue berries hang down under the foliage like bunches of grapes.  Let the fruit dry if you want to start new plants.  No one has been successful taking cuttings so you must propagate from seed. There is a planting of fringe trees outside my U of L campus office and I have enjoyed the grape-like drupes this summer, highlighting the seasonal interest of this native plant.

Chionanthus virginicus has an Oriental cousin, C. retusus, or the Chinese fringe tree.  It has similar growth habit to the native fringe tree; however, the panicle blooms are less fleecy, creating a more snowball appearance.  The Chinese fringe tree is even less particular about its soil requirements; it will do well in acid or alkaline soil, sand or loam.  It does, however, prefer full-sun, holding up well through hot summers because its leaves are more leathery.