The Placitas Gardener
Beware the bark beetle’s return
—Peter C. Benjamin
I received more than my share of calls last year from friends and neighbors regarding the epidemic-level infestation of bark beetles attacking conifers in the area. Some people were losing a significant percentage of piñon pine, and unfortunately I was only able to impart the same advice as that of agriculture extension agents and forest entomologists, which didn’t provide much hope. In fact, aerial surveys have shown that thirteen thousand acres of piñon and ponderosa in patches throughout the state have succumbed to the engraver beetle and another thirty-three thousand acres have been infested.
Healthy trees have an active resin system that deters beetle colonization. When the beetle bores into a healthy tree, resin exudes through the wound and impedes the beetle’s entry, but with two years of severe drought, many trees are under stress and have very low resin systems. Sort of an immunodeficiency condition in human terms. Engraver beetles, commonly known as bark beetles, feed on the phloem tissue, the substance just beneath the bark that moves the sugar from the foliage to the roots, according to Bob Cain of NMSU’s extension service. The beetles, which are slightly larger than a pinhead, also introduce a fungus that blocks water movement from the roots to the top of the tree.
As a last ditch effort, I used to recommend using Lindane, but that pesticide has now been banned due to its toxicity, not only to the target pest but to beneficial insects and fauna as well. I really hate being totally helpless, but one has to be philosophical when dealing with nature. Well, hopefully there is now help.
A friend and colleague who is also a research scientist has developed a product that has shown positive results. However, I am currently doing my own testing in the area and if my results prove positive as well, I will share this with you in a future column. The product is a disease preventive that has also shown its ability as a restorative in the case of infected trees. Let me explain a bit about how this agent works.
Monoterpenes are sent out by trees to alert their brethren of impending attack. There are documented examples of one tree under attack by a pest sending signals via monoterpenes to relatives in the area which in turn raise their levels of certain chemicals that repel the pest or even produce a toxin that the attacker cannot tolerate. Unfortunately, these chemical signals are also picked up by the pests, so when a tree is under stress, the pests also know this and attack the weakened tree. To make matters worse, the beetle or other pests will send out a pheromone that alerts others of its kind in the area that the buffet table is open, which only serves to exacerbate the problem, and before you know it, the host tree is done for. Beetles have such a broad range of pheromones that they can even signal telling when a host tree under attack is at maximum capacity and other beetles should find another tree. The beetles can actually determine what variety of tree to attack based upon the scent of the monoterpenes, so when a piñon is stressed, chances are good that all piñon will be easy prey and the pests target this variety. The same thing can happen to ponderosa pine and other conifers as well.
So the answer to the problem came quite easily to my friend: he changed the aroma of the monoterpenes to fool the beetles into thinking that the tree is healthy, and also incorporated curatives that would maintain the overall health of the tree.
Essentially, he developed a liquid product that is diluted with water and then drenched or sprayed on trees and plants, and the best thing about it is that it meets all the necessary criteria to be recognized as a certified organic product by the state of Colorado. The product is called Agri VPX and is only available to licensed applicators, not because of its potential as a toxic agent but because of the precise dilution rates required for effectiveness. A consumer pack is currently under R and D and should be available soon through a distributor I’ll name when it is selected. Weekly treatments of three to six months of intense use are required, followed by a simple maintenance program.
In the meantime, there are other preventive measures one can take. Solarize your green firewood by stacking in four-by- four-by-four-foot stacks in direct sunlight, draped with polyethylene. The greenhouse effect should kill the pests. Firewood seasoned for a year or more should be free of beetles. Avoid construction that disturbs roots or causes injury. Prune only between September and March. Thin any trees that are overcrowded so that competition is lessened for scarce water. Water trees deeply during periods of extended drought (where this is practical). Fell, remove, and chip or burn infected trees immediately.
Although our last frost average is the third week of April, instead of forcing an early crop of veggies by employing hot caps and walls-of-waters, I’m going to try and exercise some patience this year and plant most of my warm weather crops in early May instead, with the exception of squash, which I’ll plant in June to try to avoid or minimize the devastation brought on by another of my archenemy insects, the dreaded squash bug.