Often property owners or land managers have several trees of significant value to the landscape. These trees may be prized for their size and/or aesthetic value. With the re- cent extreme drought conditions, the bark beetle has become a formidable pest. Therefore, it is important to understand methods and control strategies that minimize the impact of this pest.
It is critical in the management of these trees that lowering tree density through thinning gives the best long term benefit in reducing the risk of damage from bark beetles. (For more information on thinning refer to: Guidelines for Thinning Ponderosa Pine for Improved Forest Health and Fire Preven- tion, University of Arizona, College of Agriculture and Life Sciences Bulletin az1397). In addition, these high value trees can be given additional care by supplemental irrigation and being sprayed with a preventive insecticide.
The application of fertilizers will not help protect trees from the effects of drought, and will not protect against bark beetle attacks. In fact, fertilizers may even hinder the trees ability to defend against bark beetles. Fertilizers often cause trees to put on extra growth; this growth will require higher levels of moisture to maintain healthy conditions. Fertilizers may also burn foliage if improperly applied. For additional information on irrigating trees refer to “Beyond the Ponder- osa: Successful Landscape Trees for Higher Elevations in the Southwest”.