Drought impacts to evergreen trees

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Many evergreen trees (pine, pinyon, and spruce) are currently exhibiting decreased vigor, twig dieback, and needle browning or needle drop. The primary cause of these conditions is prolonged drought. Dry air, low precipitation, low soil moisture and fluctuating temperatures are common conditions in western Colorado and trees can usually bounce back after one or two low-water years; however, stresses from prolonged drought harms trees by damaging root systems, reducing plant vigor and leaving trees more susceptible to insects and disease.

Homeowners can take specific steps to improve the survival rates of landscape trees. When selecting trees, be sure to ask local experts for trees that will thrive in specific local site conditions. Important considerations include drainage, soil chemistry/pH, water requirements, and elevation. During prolonged drought, landscape trees may require substantial additional water depending on tree age and local conditions. Properly applied fall and winter watering can also help, especially in years when sparse snow cover results in decreased soil moisture.

It is also important to recognize the signs of insect infestations as drought-stressed trees are less able to fight off impacts from insects. The most common tree insects recently reported in Rio Blanco County include Coolie Spruce Galls, Pine Needle Scales and IPS Beetles. Spruce Galls normally occur and do not pose a serious threat to conifers. Pine Needle Scales can be treated and conifers will survive their presence. ISP beetles and other pine borers are more serious. Once a tree is infested, it is just a matter of time before that tree dies. Homeowners can prevent their remaining trees from becoming infested and alter landscape practices to improve overall health and vigor of remaining trees.

Download fact sheets at: https://www.rbc.us/205/CSU-Extension

For additional information, call Linda Masters at the Extension Office (970) 878-9490.