Why do trees die?

Carson City has some of the oldest ornamental trees in Nevada as I recently learned on the Carson City Historical Society Garden tour. The Crisler house on Minnesota boasts the oldest and largest black walnut tree on record in Nevada. The biggest boxelder tree in Nevada is at a Mountain street home. The Bicentennial Tree at the corner of Division and Washington streets is one of the oldest cottonwoods in Nevada.

With this evidence of trees living to great maturity in our area, why do many trees die fairly young? According to Clemson University, ornamental trees rarely live as long as their forest counterparts, generally surviving about 32 years, while forest trees may last hundreds of years or more. Inner city trees live only about seven years. Of course, few of the ornamental trees in northern Nevada are native to our area and our climate certainly contributes to early tree decline.

Besides the stressing influence of this climate, people rarely focus on tree health care, instead responding only to tree problems. This is like not taking care of your body and having to go to an emergency room because your neglect led to a health crisis. Proactive care is always better than reactive care.

Each tree has a genetic code that governs its growth potential. The environment and pests, including diseases, can weaken a tree. The black walnut I mentioned above is diseased and dying. Winds, fire, lightning and other catastrophic events can also damage or kill trees. Trees, particularly young ones, can die from lack of water or improper planting. What causes older well-established trees to die is that they run out of energy. The size and structural complexity of a mature tree demand a huge amount of energy, leaving little available for emergencies, such as pest attack, drought stress, winter dieback etc. A tree has to produce a lot of ‘food’ through photosynthesis to support all the woody tissue in the trunk, branches and roots. Mature, healthy trees are in a delicate balance with their environment, especially in Nevada.

The key to keeping a mature tree thriving is to maintain that balance through optimal irrigation, fertilization, pruning and soil maintenance. This includes protecting the roots from compaction, digging, grading and soil filling.

I took this article from Tree Health Care: Managing Natural Changes, Clemson Extension, Forestry Leaflet 18 (http://www.clemson.edu/extfor/publications/forlf18/).

Free Grow Your Own classes begin July 8 through August 26, from 2:30 to 4:30 p.m. at 2621 Northgate, #15, Carson City. For more information see www.growyourownnevada.com or call 887-2252.