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By ANNE LENOX BARLOW, Cornell Co-op Extension
Depending on whether you live in the Champlain Valley or the Adirondack Mountains, you are either in the midst of peak fall foliage or your trees are just starting to come into peak color.
The colder areas of the region are already seeing quite a bit of fall color, while the warmer protected areas are still about a week or so away from the bittersweet color show Mother Nature provides.
If you are like me, you love the bright reds, oranges and yellows autumn brings. While the timing of the leaf transformation from green to the warm fall colors depends on the tree's species, it is easy to notice that most trees' color changes are fairly synchronized. The maples go at about the same time, while oaks hold onto their color a bit longer.
But have you ever wondered about those trees that start to show their colors in August and early September?
Are they trying to get us excited about the show that is about to come? Or is it something else?
There is actually a simple one-word explanation to premature coloration — stress. When a tree is under stress and cannot support its leaves, it starts to shut down, just like they do in the fall in anticipation of the winter. As the leaves shut down, the green chlorophyll dies off and the red, orange, and yellow pigments are visible.
MOTHER NATURE
If trees aren't worrying about their jobs, kids and finances, what could possibly cause them stress? There are many answers to that question:
Dry weather reduces the amount of food a tree can make during the growing season, causing stress. Watering during dry periods reduces it.
But at the same time, wet weather can cause stress because tree roots need both water and oxygen. If the soils stay wet too long, the roots lack oxygen. Not planting in areas that have poor soil drainage is the best way to avoid this type of problem.
Snow, ice and lightning can damage a tree's crown. Protecting a large mature tree from this is difficult, if not impossible. Asking Mother Nature to spare us from ice storms and lightning strikes is the best we can do, but if the damage occurs, proper pruning can help alleviate the stress.
Construction equipment, lawn mowers and weed-wackers can damage the tree's bark. Just under the bark is a very thin layer of specialized tissue called the cabium, which produces all of the trunk's food and water transporting cells that in turn become wood and bark. If the cabium is damaged, the tree is under a great deal of stress. Proper mulching and keeping equipment away from a tree's trunk can reduce the likelihood of this happening.
INSECTS, DISEASE
Construction can also damage a tree's root system by either digging up its small feeder roots or by compressing and compacting the soil so much that the roots have a difficult time getting water and oxygen. If you are having any type of construction done, plan ahead. Keep heavy equipment, foot traffic and stockpiled building materials away from trees. If traffic has to travel near a tree, fence off the area closest to it and make a path of mulch several inches thick to help distribute the weight.
Insects and diseases also cause tree stress. Sometimes they will result in the entire tree prematurely changing color, but other times it may only affect a branch or two.
If one or even several of your trees shows signs of stress, there are some steps you can take. Never let the trees become water stressed. Plan on having an arborist remove dead wood in the canopy. Seriously consider removing the turf from the trees' root systems and replacing it with mulch and low-growing shrubs and herbaceous perennials. And if you have to have the tree removed, research what type of tree would be a good replace for the site or if the site is even appropriate for any type of tree.
Anne Lenox Barlow is the horticulture educator with Cornell Cooperative Extension in Clinton County. Office phone numbers: Clinton County 561-7450, Essex County 962-4810, Franklin County 483-7403. E-mail questions to: askMG@cornell.edu.
