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Issue link: http://read.dmtmag.com/i/46119
Story and photos by Matthew Stephens, Director of Street Tree Planting for the City of New York Department of Parks & Recreation Debunking a Tree Planting Myth: Fall Transplant Hazards Story and photos by Matthew Stephens, Director of Street Tree Planting for the City of New York Department of Parks & Recreation B&B trees dug properly—i.e., when dormant. Some trees are simply more difficult to transplant than others. Furthermore, when trees are harvested and/or stored improperly, the likelihood of tree mortality increases. Complicating the issue is the fact that it is difficult to trace tree mortality back to one finite reason. Tree mortality is a tapestry of interrelated issues that compound and result in tree death. One facet of transplanting around which there has been much confusion is fall harvesting of B&B trees. There has been some reluctance among the nursery and landscape industry to dig certain species of trees in the fall, but this "fall hazard list" var- ies among nurserymen. This reluctance is not unwarranted, but when certain precautions are taken, tree harvesting of all species may occur in the fall. B&B tree harvesting is in itself a miraculous feat. Research suggests that as little as two to eight percent of roots actually accompany a tree once it has been harvested in the root ball. Furthermore, as tree caliper increases, so does the amount of time needed to reestablish a balance in the root:shoot ratio, but with appropriate soil moisture and enough time, transplanted trees will reproduce their root mass. Trees with a more fibrous root architecture regenerate more rapidly than trees with a more prominent tap root. Additionally, research has suggested that most root growth slows significantly once soil temperatures reach 50 degrees F (10° C) and winter dormancy approaches. When trees are harvested between late fall and early spring, root elongation virtually ceases. Therefore, 36 These hedge maples (Acer campestre) were dug too early. if the tree's root system is essentially static, it should make no difference if a tree is harvested in the fall or early spring. There must be other variables at work that ensure success of a trans- plant. The following list considers four major factors for a suc- cessful tree harvest and transplant. 1. Harvest at the Right Time During the fall, trees reach dormancy at different rates/on different schedules. One reason that some trees have been thought to be fall dig hazards (see table) is that they have been harvested too early. Some trees go dormant very late in the fall depending on weather patterns, and if the weather turns cold quickly, growers will not City Trees