Tree Care Tips and Tricks

Unfortunately, two tree pruning practices seen much too often in our neighborhoods are topping and over-thinning. I will touch on over-thinning in this article and topping in a later article. There are ways to lessen your odds of improper tree care, and an important first step is to hire ISA Certified Arborists or Tree workers. Certified Arborists are individuals who have achieved a level of knowledge in the art and science of tree care through experience and by passing a comprehensive examination developed by some of the nation’s leading experts on tree care. Another important step is to make sure the tree service has a valid license issued by the California State Licensing Board. You can verify the legitimacy and validity of the license by calling 1-800-321-CSLB, or use the website www.cslb.ca.gov. And it is also a good idea to ask for proof of liability insurance. Ask for a copy of the insurance certificate and verify that it is valid and covers the type of work being performed for you. If you hire a tree service that does not have liability insurance, you may responsible for injuries or damage incurred during the work performed on your property. More information can be found at www.TCIA.org, or by calling California Association of Tree Trimmers at 888-436-2541. Once you decide to have work performed, keep in mind that the most important pruning takes place when trees are young as this is the time to prune for the future structure of the tree. Having the proper pruning performed at this stage in the tree’s life can eliminate the need for corrective pruning when the tree is larger and thus at greater risk for decay if large cuts need to be made. Therefore, when pruning mature trees, work should ideally be limited to “crown cleaning.” This removes dead, dying, diseased, crowded; weakly attached and low-vigor branches form the crown of the tree. Not to be confused with the former, “crown thinning” should seldom be performed. And, when it is, no more than a maximum of 25% of live tissue (limbs and foliage) should be removed (even 25% is considered too much by many in the tree care industry). Thinning, unfortunately, is another misused practice undertaken by some tree pruning companies. In these cases, what actually happens is the limbs are pruned in a manner that leaves them with the appearance of what is commonly described as “lion-tailed.” This is the practice of removing all of the growth from the inside at branch attachment towards the outer branch tips. In contrast, proper thinning is the selective removal of growth from the tips of the tree towards the inside. ISA Certified Tree Workers and Arborists understand these proper pruning techniques. Some problems associated with lion-tailing are: • Exposure of the bark to the sun resulting in sunscald and cracking of bark • Rapid increase of growth, which depletes the tree of its natural reserves (food) and increases the likelihood of disease and pest problems. • A lack of branch taper, which can lead to branch failure. • The removal of living tissue decreases photosynthesis, which is a necessary process in the production of food for the tree for new growth and fighting disease and pest problems. There are many things to consider when hiring a tree service to prune your trees, those mentioned above are just a few of them. You can find more information at www.treesaregood.com. This site has 18 informative brochures covering many aspects of tree care. You can also get these free brochures at City Hall on the second floor lobby area. If you have any questions, you can call the City Arborist (John Davis) at 925-943-5854 x281 or email at jdavis@walnut-creek.org.