Dirr, Michael A. 1982. The great elm debate — Siberian vs. Chinese. Am. Nurseryman 155(4): 75-79.
Siberian and Chinese elms represent the greatest case of misidentification since “The Prince and the Pauper.” No two trees have been more confused by the American nursery trade than these. The Chinese elm offered by most nurserymen is, in fact, Siberian elm (Ulmus pumila), a woefully inferior tree. True Chinese elm (U. parvifolia) is infinitely superior as a landscape specimen, but it is not widely available. E.H. Wilson noted this problem in “Aristocrats of the Trees” in 1930. “I fear many years will lapse before the confusion existing between them is straightened out,” he said. The American gardening public has been the loser in the great elm debate. Ulmus pumila was introduced into North America in the early 1900’s. It found wide acceptance among nurserymen who raved about its rapid growth and tolerance of almost any soil. Ulmus parvifolia was introduced into cultivattion in the late 1700’s, but it has never become a popular landscape tree. Its great beauty resides in its oval to rounded crown of gracefully spreading branches. Its mature height and spread are approximately 40 to 50 feet.
Haller, John M. 1982. Common tree ailments and what to do about them. Am. Forests 88(2): 27-30.
What do you do with a sick tree? Sometimes, unfortunately, the answer is “nothing.” In many cases, however, the owner can take measures to prevent disease from getting started, or can assist a diseased tree toward recovery. We can call such measures protection, eradication, and immunization. Protection means prevent. Certain practices will prevent the onset of disease. Prominent among these is anticipatory spraying, which prevents many diseases from taking hold. Trees growing in good soil and receiving abundant water are more resistant to disease than trees growing in less favorable situations. Hence the best step in protecting a tree is to improve the soil and to stabilize the water supply. Eradication means the elimination of diseased parts. Eradication also involves cavity repair, treatment of cankers, and other surgical measures. Another form of eradication involves the elimination of an alternate host that is necessary in the life cycle to the pathogen. Immunization means two things: 1) the development of disease-resistant strains that may be planted in infected areas with impunity; and 2) the use of chemical compounds that act inside the plant to increase its resistance to disease.
- © 1982, International Society of Arboriculture. All rights reserved.
