A SECOND CHANCE FOR ELMS
Tree favorites become fads. A tree with an interesting shape, beautiful Spring flowers, or gorgeous Fall color can become so popular that it is over-planted, developing a major problem for the species. Diversification is the word for city landscapers today, keeping the single species epidemics at bay. This lesson was realized in the case of the American Elm. It was the shape of the Elm that made it so popular. It was fan shaped, the branches grew high and curved down, giving much shade and little obstruction. No other tree could compete with the elm as a street tree.
"Elm Street" is the thirteenth most popular street name in the United States. Then, the European Elm Bark Beetle arrived, carrying a fungus that strangled the elms. The elms fell to the saw in a race to stop the beetles’ spread. It was not fast enough, and another approach was
Heart broken cultivators went to work to develop a disease resistant substitute. Luckily, there were several disease resistant elms available; but, they did not have the characteristic shape. By using cross breeding and cloning, the scientists developed worthy cultivars. Now, they are on the market. Here are a few of the leaders to be considered:
• Valley Forge has a classic American elm shape, upright arching, broadly V shaped branch structure with a full, dense canopy. Controlled screening for Dutch Elm Disease showed Valley Forge to be resistant. It was introduced by the U. S. National Arboretum.
• New Harmony is a second successful introduction by the National Arboretum. It has a broad vase shape crown; The main trunk divides 30 feet above the ground, giving the tree a tall, sweeping look. It was discovered in Ohio.
• Accolade Elm is a cross of Japanese and Chinese species selected for its vase shape, vigorous growth, excellent drought tolerance and good strong yellow fall color. It has excellent disease resistance to both Elm Yellows and to the dreaded Dutch Elm Disease. It is from the collections of the Morton Arboretum and is released through Chicagoland Grows Plant Introduction Program * through local garden centers. Mayor Daley chose Accolade Elm to bring elms back to Grant Park in 2002. Other elms developed by Dr. George Ware and his staff at the Morton Arboretum and distributed by Chicagoland Grows are Vanguard Elm, Triumph Elm, and Commendation Elm.
* Established in 1986, Chicagoland Grows is a unique partnership between the Chicago Botanic Garden, The Morton Arboretum, and the Ornamental Growers Association of Northern Illinois. Collectively, the partners work with other industry professionals throughout North America to select, evaluate, produce, and market new and recommended plant cultivars with proven performance under northern growing conditions. Before a plant can be introduced through Chicagoland Grows, it must be evaluated under a variety of landscape and nursery conditions for up to ten years. Once approved, these plants may be produced under license for open market sales. Chicagoland Grows plants are sold through wholesale as well as retail nurseries and garden centers throughout the United States. Have you discovered or bred a new plant? If you know of a plant that would be a good candidate call Chicagoland Grows at (847) 835-8301.