You bought your house because it was surrounded by a forest of pine trees that reminded you of Lake Tahoe. You love the trees and the atmosphere they provide. Then one day to your horror you notice that your beautiful pine trees are not looking so good. Much to your alarm, they are turning reddish-brown. Oh, no! This can’t be happening! There must be something you can do to reverse these sequences of events.
Know your Monterey pine
To understand what is happening to your Monterey pine it is helpful to know a little bit about the species. The Monterey pine naturally grows at only five locations in the entire world: three in California and two in Mexico (on islands off the Baja Peninsula). The three locations in California are along the coast: Ano Nuevo, Cambria, and yep, you guessed it, the Monterey Peninsula. These locations all have one thing in common – they are part of the fog belt and provide a cool, moist environment for the pines. They are not necessarily in a high rain fall area but the fog is dense enough that it can drip an additional 2 inches of water from the branches onto the ground.
However, the Monterey pine has proven to be hardy enough to survive quite well outside of its natural habitat throughout the world. However, less rainfall and fog does impact their longevity. In their native habitat the Monterey pine can live 90-120 years. Beyond the fog belt in hot, dry Contra Costa County, the Monterey pine usually lives 50-60 years.
Knowing how old your tree is can help determine if it is rapidly declining from an attack by insects or if the tree is in its twilight years and is in a slow death spiral.
Bark Beetles and your Monterey pine
The biggest, and most destructive threat to Monterey pines (and actually all pines) is the ips beetle, a member of the engraver beetle family. The beetle bores into the tree and create galleries just underneath the bark. The beetles carry a certain microscopic fungi which is deposited in the vascular system of the tree they attack. The fungi multiply quickly and clog the water-conducting tissue of the tree, which doesn’t allow the water from the roots to reach the foliage nor the food from the foliage to reach the roots. You can identify the ips beetles by its pitch tubes, overflowing with frass, along the trunk and/or branches of the tree. A beetle attack on a pine tree can be swift. A pine can go from dark green to lime green to yellow to red all within a matter of weeks!
Will watering help my Monterey pine?
Bark beetles target weakened or stressed trees so reducing stress is the most effective way to help your Monterey pine. A general guide is to irrigate infrequently, such as twice a month during the dry season. However, a sufficient amount of water must be used so that the water penetrates deeply into the soil (about 1 foot below the surface). We have found using a drip hose, circled around the tree at the edge of the drip line, is the best way to water pines. In clay soil, ubiquitous to Contra Costa County, it can take an hour for the water to penetrate an inch. Therefore to reach 12″ deep you would need to leave the drip hose on for 12 hours or overnight.
Does pruning help?
Proper pruning out of infested limbs and the removal of dying trees can help keep bark and wood-boring insects from emerging and attacking other nearby trees. However, the timing of the pruning is critical. You want to avoid creating fresh pruning wounds during the adult beetles’ flight season (when the weather warms up and they are active). Therefore, do NOT prune pines from February to mid-October.
However, if your Monterey pine is “over mature” (meaning it is in the final third of its life span) it might be more cost effective NOT to remove the deadwood and put that money toward the tree’s eventual removal.
My Monterey pine is at least 50 years old, should I remove it?
No one, including experienced arborists, can predict the exact year your tree will die, but they can make a pretty accurate guesstimate based on their years of experience in the field. If the tree is declining due to old age, that tends to be a slower process. If your tree is fairly healthy-looking and has no safety issues AND most important you love the tree, then keep it. Start a savings account toward its eventual removal and when the tree dies, remove it.
Once my pine dies, how quickly do I need to remove it?
Once the last needle on your pine turns red and there is no green whatsoever on the tree, amazingly enough, the pine still has some sap in it, holding the tree together. But over time, that sap will dry up and tree will become more brittle. The good news is that once the moisture content is reduced, the tree is no longer attractive to most bark beetles. The bad news is that it is then attacked by other beetles that hasten its deterioration. At this point the tree will start to fall apart, dropping limbs and large sections near the top of the tree and eventually break off at the bottom. Therefore, it is our recommendation that you remove your pine within six months after its death. Beyond that time frame, the tree becomes dangerous to climb and may need heavy equipment, such as a crane, to safely remove it.
Look up
The best way to care for your pine is to look up. Make it a habit to look up and observe the whole tree and especially its top. If your pine is starting to decline, the top is generally where it will start.
Call in a Certified Arborist
As always, if you have any questions about your Monterey pine and its health please call and schedule an appointment with one of our ISA Certified Arborists. They can inspect the tree for pitch tubes, or based on the age of the tree, predict how much longer they expect the tree to live. They can also evaluate its safety and make recommendations for pruning and/or removing the tree.