Two YFR workers aloft removing some ponderosa pines in a stand that suffered a bark beetle infestation. Can you spot them both?
We assess a lot of trees. Much of the time the issue is simply planting the wrong tree for the site conditions. We often use the expression, “right tree, right place”. To save headaches down the road, spend time evaluating your planting site beforehand. Get to know what a tree will need, and what your property will provide in terms of climate, soil moisture levels, supplemental irrigation, and sun exposure.
Generally, ornamental trees are less tolerant of drought conditions, but some are more drought tolerant than others. It’s important to consider the moisture requirements of a tree before you put one in the ground. It is OK to plant a tree that needs supplemental water, you just have to be prepared to provide it!
Another thing to consider is sun exposure. For example, trees that prefer shade, when planted in a sunny spot, will be stressed even with adequate moisture. This is often the case with dogwoods. They prefer shade and water; rarely will they thrive in a yard that has no shade whatsoever.
Blessed Are Those Who Plant Trees Under Whose Shade They Will Never Sit
One other thing we are beginning to consider as we plant trees is preparing for a warmer climate. We planted a valley oak on our property last year in Cedar Ridge around 2800’. A bit higher than its typical elevation, but it is thriving in the heat! Since valley oaks tend to be pretty spready, we will prune it to have a slightly more upright form to strengthen it for the severe winters we have been seeing.
A few water-wise trees that do great in this area:
On the smaller side: western redbud, strawberry tree, loquat
Medium: Chinese pistache
Larger: western sycamore, deodar cedar, giant sequoia, and valley oak
Bark Beetles
We have seen a good deal of tree mortality in the region due to bark beetles. Most of the infestation is in ponderosa pine trees by the western pine beetle. Healthy trees are usually not susceptible, but drought stressed trees have a harder time producing the pitch needed to prevent a successful attack. In addition, milder winters have allowed the beetles to overwinter with more success, increasing their population. If you see a lot of woodpecker activity around your pines, its likely they are snacking on beetles!
What can you do?
Thin overly dense stands to increase available moisture to remaining stems. This is best done in winter.
Avoid pruning when the beetle is active, April-November.
Sparingly provide supplemental irrigation in the hottest months, if feasible. Deep waterings 1-2x/month across entire root zone.
Pheromone repellants are available for high-value pine trees or stands. Online research gives varied opinions, but our forester friends swear by them!
If a tree shows signs of decline, remove ASAP to reduce the likelihood of spread. Chip and haul all material. If that is not feasible, pile slash away from trees in a sunny area and cover logs with clear plastic.