Attack on Ash Trees
Judy Ziemba, State Horticulture Chairman

The reports are that the Emerald Ash Borer is either near you or only a short distance away. Predictions are it will be an enormous loss for those of us that depend on Ash (Fraxinus species) as a vital part of our landscaping. The aliens arrived in cargo through the Great Lakes and now have been hitchhiking to attack and continue to move in afflicted wood, particularly in firewood. Not only green ash (F. pennsylvanica) but also white ash (F. americana), black ash (F. nigra) and several other horticultural varieties are at risk. At this time there seems to be no way to stop them, chemical and biological controls are being researched. Primary efforts have been aggressive contaimment and eradication efforts. Because the damage done is hard to identify and frequently resembles damage of the native ash-lilac borer or ash decline, observers who suspect a tree is infested should call their county Extension office or the Illinois Dept. of Agriculture’s hotline at (800) 641-3934. If we are being proactive gardeners, we can be aware of and plan for our tree losses by planning and planting a variety of trees in our yards and parks. It has been years waiting for development of replacements for the beautiful elm and chestnut trees lost in the last century, and from that lesson, we can use this season to study and choose replacements while the bones of our gardens are obvious.

Keep in mind several attributes to consider whenever you plant something so long-lived as a tree. The estimated mature size is frequently overlooked and the tree sited too close to existing buildings or utility wires. Shapes can be upright, weeping, mounded, pyramidal or spreading. Other issues to ponder are your soil type, sunlight and fertility. Special attributes to think about are interesting bark, leaf retention, autumn and summer color. Will flowers be a pleasing color and will fruit be persistent for winter or drop on the drive or walkway? Are you interested in attracting birds or butterflies, resisting deer or Illinois native species? Are there cultivars that minimize undesirable characteristics? Consider the “four season” trees that provide color or texture throughout the year. Floral and foliage colors are givens in the spring and summer, but choose varieties that give autumn color and winter interest in form or bark textures. Native trees and large shrubs can fill a niche and give a great deal of pleasure. Clusters (mini grove) of small trees might be more in scale with your landscape. Avoid the trees that are really not suitable in your planting zone or are prone to disease and insect attack.

Some underused tree varieties include the Seven-Son Flower (Heptacodium miconiodes) introduced in 1980. It is a bit awkward when young but forms a spreading canopy and creamy fragrant flowers that appear in August to October. The flowers are replaced by bright red calyces, which give a great show in late autumn Growth is 10 to 20’ and it is suitable for Zones 4-8. The Chinese Fringe Tree (Chionanthus retusus) grown as a single stem, is a beautiful small tree. It is covered with white flowers in April and May, with fruits on the female trees and a gray ridged bark when mature. it is easy to grow in most soils, prefers sun but will take a bit of shade. It grows 15 to 25’ high and wide and is reported hardy to Zones 5-8. A native I enjoy seeing is the Spindle or Eastern Wahoo tree (Euonymus atropurpurens). It is a beautiful native tree, is barely known, but when seen with its pink dangling pods and gorgeous fall color, it cannot be forgotten. It is an understory tree if grown single stem.

If you want a larger tree, check out the Goldenrain Tree (Koelreuteria paniculata). It is fast growing in moist soils. At age 3 or 4 years, it has rich yellow panicles appearing in June and July on the ends of the branches and will survive in drought, heat and wind. It can reach heights of 30 to 40’. Kentucky coffee tree (Gymnocladus dioicus) is a durable native tree with bold winter habit and handsome, ridged bark. The large, compound leaves are pink tinted when unfolding, developing a beautiful blue-green summer color and often turn clear yellow before falling, As a youngster the tree is a bit ungainly but with age the habit becomes more uniform, producing a picturesque crown of rugged branches and the handsome bark forms with interesting scale-like ridges that add to the winter landscape. It adapts to a wide range of conditions such as heavy clay, drought, and city conditions. The mature height is 50’- 60’ tall and 40-50’ wide and it is hardy to Zone 3b. Female plants produce beautiful mahogany colored seedpods that persist through winter. The early settlers used the seeds as a coffee substitute.

Planting trees is a legacy project so make sure your choices reflect some thought and planning.