When diagnosticians at the University of Illinois Plant Clinic receive a tree sample, the first observation often involves assessing tree health. We can tell whether a tree is stressed based on size and color of leave and the amount of new stem growth at the stem terminal. It helps to know how to make a simple observation on tree growth. The stems on a sample will show you how well the tree has been growing. Follow the tip of the branch to the place where a series of very close rings encircle the stem. That is one year’s growth. Continue down the stem to the next set of rings for the previous year's growth, and so on. Most tree species should be developing 8 to 10 inches of stem per year. Shaded areas do not develop as quickly, however, so it helps to know where on the tree a sample was taken from. Authors including Michael Dirr, in Manual of Wood Landscape Plants, state an expected amount of stem growth for a species. If you assess the amount of growth over the last several years on a stressed tree, you can often determine when the stress started. This can help determine the original problem, such as construction injury, the year a car ran into the tree, and other memorable events.|
Sometimes I feel like a broken record (if anyone out there remembers records!) The most widespread tree problem we see at the Plant Clinic seems to be deep planting and the decline that follows. If a tree trunk does not flare at the soil line, it may have been planted too deeply. The first root that connects to the trunk should be just below the soil. Trees that are planted too deeply, or that settle with the same result, may slowly decline. The base of the trunk must be exposed to air, not buried in soil. Placing deep piles of mulch at the base of the tree compounds the problem. Pull the mulch back from the trunk a few inches and let the trunk breathe.