TRANSPLANTING BARE-ROOT TREES: SUCCESSFUL AND COST-SAVING
Due to a major budget cut, a city in New York decided to try installing bare-root trees in their street tree-planting program. The city of Ithaca, N.Y., teamed up with Cornell University's Urban Horticulture Institute to develop a system of planting shade trees that has saved the city money and continued their tree-planting program. Nine years and at least 1,000 trees later, they have determined that they can successfully plant 1.5- to 2-inch caliper bare-root trees along their city streets through the use of a hydrogel slurry root dip applied immediately after harvest. The roots are then bagged and kept in the shade until the trees can be planted. Because the trees don't have the heavy rootball, they ship cheaper and can be managed by one person. The program has seen successful transplant of many species in both spring and fall. Only deciduous trees are candidates for this method, and the trees must be planted while dormant. Included in their list of easiest to transplant are five maples: Acer x freemanii, A. campestre, A. truncatum, A. platanoides and A. pseudoplatanus. Red maples — and oaks in general — proved more difficult to transplant. Other easy-to-transplant species include crabapple, Japanese tree lilac, black alder, ash, ginkgo, honeylocust, Kentucky coffee tree, linden, elm and Japanese zelkova. In addition to the cost savings, the program has resulted in fewer trees being planted too deeply because the root flare is easy to see on the bare-root plants and a heavy root ball is not sinking into the soil. Transplant stress also is somewhat reduced by this method because the bare-root trees have 200 percent more roots than a traditional balled-and-burlapped tree, due to different harvesting machinery. In addition, girdling roots are easier to spot; again, because the entire root system is temporarily open to inspection. The hydrogel is a synthetic, non-toxic product available in fine or course grades (the fine grade provides better coverage and, consequently, more protection of the absorbing roots).
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