If you keep your eyes out, you may have noticed lots of Pine trees around town that are brown. We had a really dry Summer, so one might think they must be thirsty right? Yes, and no. More than likely, the pine trees have been hit by Pine Bark Beetles. An, almost always, instant death for the tree once infested.
Pine Bark Beetles live out most of their life cycle inside the xylum and phloem (pronounced Zy-lum and Flow-um) of Pine trees. Xylum and Phloem of any plant are the up and down veins that carry nutrients around in a plant. If some of these "veins" are damaged, a tree could survive, but would be stressed until the bark could cover the damages. If a tree is girdled or damaged around the entire trunk, the tree can no longer move nutrients and water around and it will soon die.
Pine Bark Beetle adults drill into the sides of trees which leave a sap flow behind called "Pitch Tubes." Another sign the adults have infested the tree is sawdust will sometimes be collected around the base of the tree. Once the adults have entered the tree, they lay eggs that then hatch out and begin eating all the yummy sweet sap inside the tree. This is a huge problem since the beetles make their way around and up and down the trunk. They essentially block the flow of xylum and phloem, girdling the tree from the inside out. Water and nutrients can no longer get from the roots to the needles, thus the tree dies within a week or two. There is no saving a tree once the leaves turn brown. Once the larvae in the tree have matured, they bore themselves out of the tree, and fly to another one close by. The cycle continues.
Pitch tubes left by Pine Bark Beetles
Sawdust at base of tree from Pine Bark Beetles
Bark removed to show the tunnels left inside by the beetles
There are two MUSTS where Pine Bark Beetles are concerned. First, once a tree turns brown and dies, it must be cut down and hauled away so the adult beetles do not infest other trees on your property or your neighbors property. Cutting the tree down and not hauling it off is the same as not cutting it down. The beetles can still leave the tree and move on to another. The safest thing to do is burn the wood. Second, spraying the surrounding trees with Permethrin is essential to stop the adult beetles from flying onto neighboring trees and infecting those. This is really the only preventative method against Pine Bark Beetles. Again, there is no saving an already dead tree, but there is something to help the living! (On a side note, I again like to warn people that Permethrin is toxic to cats and fish. Do not spray around lakes or ponds, and keep all house cats inside until the chemical has fully dried before letting them back outside.)
The beetle infestation can be quite costly if not caught right away. The pictures from above come from my client who spent $6,000 to have about ten trees removed from her property. The tree company wanted to also remove another 30-35 more after they finished because they could see that the pitch tubes had started in other trees, but the leaves were still green. They removed her trees and sprayed her entire five acre property. We are hoping the 30-35 trees will make it after being sprayed. It is a sad thing to loose so many trees at once, some of which were over 75-years-old.
This summer was extremely harsh to most plants. We were very dry and very hot. Trees then fell susceptible to infestations of bugs and diseases that ordinarily wouldn't have phased them. It's very hard to deep root water five acres, but homeowners on smaller properties in subdivisions can help trees through stressful times by leaving a soaker hose on during the hard times of drought. This will help the trees develop deeper root systems where it can find its own water when rain is minimal. This might not prevent all things from happening, but a healthy plant is much less susceptible than an unhealthy plant.
So keep your eyes out for dead pine trees on your property and neighbors property. You might be able to save a tree of your own, or at the very least, inform your neighbor on how devistating the Pine Bark Beetles are if you notice them on their property.