Diagnosing tree problems can be rewarding but often frustrating because we often see only a part of the problem. In addition to observing leaves and stems, it is helpful to see the entire tree, the pattern of injury, the condition of surrounding plants, the lay of the land, and the activities that go on around a tree. At this time of year, we commonly see tree twig dieback and leaf spotting at the Plant Clinic. Observing branch terminals helps us determine how long the tree has actually been stressed. You can make this observation, too. The idea is to look at stem growth in length over several years. The terminal bud each year leaves a scar on the stem, seen as multiple rings around the stem, as if a rubber band had been tightly wrapped at that point. The distance between terminal bud scars from two successive years is the amount of growth for that year. Multiple years of 1 to 2 inches of stem growth clearly indicate a stressed tree. Compare growth of shady areas of the tree with sunny areas to get a true picture of growth. Often tree identification books such as Dirr’s Manual of Woody Landscape Plants indicate a normal amount of growth for a species.
Many of the deciduous tree samples we have received at the Plant Clinic this spring have shown scorching, wind tatter, and perhaps cold injury. Often these same trees have shown poor stem growth for at least 3 to 5 years. Follow-up questioning and photographs of the lower trunk frequently show that the tree was planted too deeply. Deep planting can cause slow decline of a tree over many years. It may not kill the tree but does not allow the tree to thrive. Does a tree that is planted too deeply need to be removed? That is not usually the case, but arborists can help the tree grow better. Deep planting is a major problem in our landscapes and one that is completely avoidable.
The International Society of Arboriculture (ISA) created www.treesaregood.com to provide quality information on tree care to the public. A section on planting new trees explains the planting process and has a helpful diagram to illustrate major points. One crucial mistake often made in planting is placing the root ball in the soil exactly as it comes from the nursery. Because nurseries use cultivation to cut down on weeds (and avoid herbicides), and because cultivation often throws soil up around the base of the tree, some of this soil may need to be removed before planting. Identify the trunk flare (where the roots cause the trunk to widen) and be certain this flare is partially visible when the tree is planted. The tree should be planted so the first root is just below the soil surface. Do not bury this flare with mulch once the tree is planted. Other details--such as digging the correct hole, mulching, and follow-up care--are discussed on the ISA Website. Taking the time to plant your tree correctly can help ensure a healthy tree for many years to come. Deep planting only causes years of tree decline and frustration in tree care.