By Glenn DiNella
Back a few hundred years ago, when I was studying landscape architecture at North Carolina State University, I had the great fortune of taking a few classes with horticulture professor Dr. J.C. Raulston. Possessing a keen mind, a vast knowledge of plants, and a likable personality, J.C. (as he asked to be called) was one of my favorite professors. He was one of everyone’s favorites.
A car accident took J.C. from us in 1996, but his name lives on in N.C. State’s J.C. Raulston Arboretum in Raleigh. This time of year I think of J.C. often as I cast a wary eye at trees sporting vivid fall colors.
One thing he pointed out was fall foliage can be a clue to the health of a tree. If you spy a tree changing colors much earlier than other trees of the same species, it might be a sign of stress. Particularly vivid colors (brighter than other trees of the same species) also can indicate stress.
You might notice that urban street trees—typically encased in tiny tree wells and surrounded by impervious paving—turn early and don bright cloaks of foliage. Street trees are usually stressed and have very short life spans compared with their country cousins.
Maple trees, J.C. pointed out, have a bad habit of splitting the bark on their trunks. We all know maples are loaded with sap. In the winter, the sap warms up in the southwest side of the tree in the afternoon, then rapidly cools at night. This can cause cracking, especially on younger trees that haven’t developed thicker bark. Open wounds allow insects and disease to enter, further stressing the tree.
There are several ways you can help prevent your trees from getting stressed. First, plant them where their roots and branches have room to grow without excessive pruning. If you have limited space, select a species with a small stature. Or look for a dwarf cultivar.
Large trees surrounded by grass benefit from the fertilizer and water you lavish on your lawn. For small, newly planted trees, use a mallet to pound two or three fertilizer spikes into the ground to provide nutrients all season. Give newly planted trees at least 5 gallons of water per week.
For young trees, or those with thin bark prone to cracking, protect trunks in winter with paper tree wrap or long spirals of white plastic, which absorbs less heat than black plastic. This also protects against browsing by small animals. Remove wrap or spirals in spring to allow for new growth.
Stake newly planted trees that are top-heavy, in windy sites, or prone to vandalism. Protect tree stems by cushioning the wires with sections of old garden hose. Stake trees for no more than one year, so they have the opportunity to develop more supportive root systems.
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