Homeowners are living with their once beautiful views turned to ash and blackened trees. Will the forest survive the effects of the Waterfall Fire? The answer depends on several factors:
• how badly the trees were burned,
• how much of their foliage they have lost,
• how vigorous they were before nature's devastation hit them,
• if we receive more than adequate precipitation for the next few years, especially during the winters, and
• how well the trees will be able to "pitch out" bark beetles as they attack over the next few years.
Bark beetles and borers serve an important role in a forest ecosystem. They cull out weak trees, leaving an arid environment's precious resources, such as water and nutrients, for the stronger trees. This allows for survival of the species. Unfortunately, after quite a few years of drought, already weakened trees have now, in many cases, lost greater than 50 percent of their needles and are in bad shape.
Homeowners want to save as many trees as they can on or around their property, but can't water the entire forest. In addition, the city water is in very limited supply. The system is just able to recharge without homeowners using the amount of water necessary to save trees.
Flat-headed borers, satan beetles, came in the thousands immediately after the fire, laying eggs on still smoldering trees and bothering humans with their biting. They departed, but others are here or on their way, including the Jeffrey pine beetle, the Jeffrey Ips beetle and the red turpentine beetle.
Will chemical treatments protect the trees? Products containing carbaryl are registered for use on pines. The best application is to spray a tree from top to bottom until it is dripping. However, it is often impossible to reach the top of the pines, and parts of the tree not covered by the insecticide will not be protected. If 80 percent to 90 percent of the tree cannot be sprayed, it may not be worthwhile. Ips and Jeffrey pine beetles can successfully hit the unsprayed portions. Whether they are able to kill the entire tree is uncertain.
Products containing imidochloprid can be injected or watered into the soil and work on bronze birch borer and elm leaf beetle. Whether these work on bark beetles and flat-headed borers is unknown. Some homeowners feel it has been effective for them in the past. It takes approximately six weeks for a tree to take it up and move it throughout the tree. Will flat-headed borers still be attacking then? We don't know. U.S. Forest Service entomologists in Davis and Riverside have said not to use merit or carbaryl. Others have recommended spraying. The experts don't agree. If I had some nice big trees around my house that I did not want to lose, I think I would use the chemical in hopes of saving my trees.
The best defense is to improve the vigor of the trees with careful watering every month for the next couple of years.
For information on landscape recovery after the fire, contact me at skellyj@unce.unr.edu or 887-2252.
For information on other gardening topics, call your local University of Nevada Cooperative Extension office. Check out many useful horticulture publications at www.unce.unr.edu. "Ask a Master Gardener" by e-mailing mastergardeners@unce.unr.edu.
JoAnne Skelly is the Carson City/Storey County Extension Educator for University of Nevada Cooperative Extension.
