Tree Care and Maintenance
Seasonal Tree Care Tips: Fall
Autumn Leaves
Autumn…that time of year when days become shorter and trees becoming splendidly colorful. Then, the leaves drop, millions of them, and most of us head out to rake and rake and rake some more. This quarter’s article explains why broadleaved trees change color and discusses whether or not all that raking is worthwhile.
Leaf color comes from natural substances produced by leaf cells. Chlorophyll, which absorbs sunlight to produce energy is the most important and its what gives leaves their green color during the growing season. Flavonoids and carotenoids—yellow, orange and brown pigments—are also present throughout the growing season but are masked by the green chlorophyll. As the days become shorter, the leaves receive less sunlight and the chlorophyll begins to breakdown, thus revealing the yellow, orange and brown pigments that were there all along. What about that brilliant red color? It comes from anthocyanin which is produced through chemical reactions as overnight temperatures begin to cool, but not all trees can make anthocyanins. Check out these resources to learn more about leaf color and leaf drop:
- Why Do Autumn Leaves Change Color, an excellent 2:20 minute Instant Egghead Video by Mark Fischetti for Scientific American
- Autumn Color, a Research Laboratory Technical Report by Bartlett Tree Experts
There are pros and cons to raking and blowing all those leaves as they drop for weeks on end. Many people prefer a tidy yard, but consider the benefits of leaving a layer of mulched leaves to actually improve the health of your grass next summer. Leaves provide nutrients and can be beneficial in moderation, but keep in mind that leaves don’t belong everywhere and it is especially important to keep storm drains clear and prevent slippery walkways. Also, never leave diseased plant material on the ground which can spread foliar fungal and bacterial leaf spots and more. Learn more about the benefits of leaving some leaves and tips for creating leaf mulch by visiting:
- “Leave” Them Alone: Lawn Leaf Management, Virginia Cooperative Extension Publication 430-521 by Mike Goatley Jr.
- For the Greenest Yard, Leave the Leaves Behind: A new reason to reconsider raking or blowing leaves this fall, Consumer Reports article by Paul Hope
- Want to Improve Your Lawn? Don’t Bag Those Leaves, from NPR’s All Things Considered
Please check back for more seasonal tree care and maintenance advice!
Link to Tree Care and Maintenance Archives
Archives
Summer 2018: Emerald Ash Borer
Spring 2018: Pruning Young Trees
Winter 2017: Tree Related Storm Damage
Fall 2017: New Tree Selection and Planting
Summer 2017: Trees and Turfgrasses
Spring 2017: English Ivy Removal
Winter 2017: Recognizing Tree Risk
Summer 2016: Drought Stress
Fall 2016: Preparing Trees for Winter
Additional Tree Care Resources:
| National Arbor Day Foundation | The Morton Arboretum |
| Oregon Department of Forestry | Tree Care Info |
| ISA Find an Arborist | Oregon Community Trees |
| Oregon Department of Forestry | Alliance for Community Trees |
Right Tree in the Right Place
Use this handy guide for assistance in choosing the right species of tree based on the constraints of a site, such as overhead wires, narrow plant strips, and proximity to structures.
"Right Tree Right Place" - helpful information such as "Use this guide for assistance in choosing the right species of tree based on the constraints of a site, such as overhead wires, narrow plant strips, and proximity to structures."
"Master Plant List" - a guide to the plants that are acceptable for mitigation requirements in Lake Oswego.