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Posted Local at Oct 02, 2010
Recently, I attended an educational program in the Brownsville area on mountain pine beetles. Most everyone is aware of these nasty little insects and the damage they are causing in the Black Hills. Mountain pine beetles do their damage to individual trees by attacking the tree, burrowing under the bark and laying hundreds of eggs. Trees are attacked by many beetles numbering in the hundreds; this means that there will be thousands of larvae in an individual tree. The program I attended started with some history of pine beetles in the hills and concluded with an in the field demonstrations of trees that have been attacked.
Dr. John Ball, SDSU Extension Forester taught participants about the biology of the insect and how it chooses weakened trees to infest. Dr. Ball explained how the beetle has appendages to harbor the blue stain fungus which is important to its successful reproduction. Adult females need to lay eggs in galleries under the bark in live trees but the next generation’s adults must be in dead trees in order to exit the tree or they would die in the process. The fungus helps to kill the tree so that the new adults can complete the life cycle. He also explained how the insects use pheromone to alert other females to a tree and when the tree has too many beetles they release a different pheromone which tells other females looking for a tree to “stay away”. This ensures that there will be the correct amount of larvae in the tree to kill it and sufficient food in the phloem to feed the developing larvae.
Bill Coburn, Certified Forester with Neiman Timber Company demonstrated techniques to determine if a stand of pines is in need of thinning, a method that deters beetles from being able to move from tree to tree as they are prefer to fly to close trees as they are lousy fliers. He let participants use a prism, a simple tool used by foresters to quickly calculate stand density. Basically, you mark a spot on the forest floor and keeping the prism over the mark look at trees and visually tell if the tree is to have its breast height diameter counted. He suggested that forested land be somewhere between forty and eighty square feet per acre of basal area per acre. He also spoke on how pine beetles prefer larger diameter pines but when there are large numbers of females they will attack smaller trees and other species including spruce. Pine beetles cannot complete their life cycle in these smaller trees or other species but these trees will also die in the process.
Carson Engelskirger, Forest Program Manager for Black Hills Forest Resource Association instructed participants in various methods to control and protect stands of pines against attack. He mentioned using carbaryl by spraying the bottom thirty to forty feet of the trunk in the spring (Memorial Day). Carbaryl has a fairly good residual on the trunk of trees as it soaks into the bark providing protection during the flight period. Insects will contact insecticide as they walk around on the tree and when they start chewing in the bark. Spraying after the insects have entered the tree will have no effect in control of the infestation. He also suggested that land owners who have forested land contact some sawmills to see if they cut and purchase the timber. He said that there has to be sufficient timber on the land before they will be interested. He demonstrated how to determine the age of a tree using a core sampler. This tool bores a hole into the tree and removes a core of the wood of the tree where foresters can count the annual growth rings. This tool enables a forester to tell how the tree grew over its life span, wet and dry periods, and even if the tree survived fire in the past.
I thoroughly enjoyed attending the pine beetle program and learning more about the insect that is damaging many areas of the Black Hills. Future programs for land owners are planned concerning mountain pine beetles. Information on these programs will be available at your local extension office or by contacting me at 605-394-2188 or e-mail to ricky.abrahamson@sdstate.edu. We will add your name to the list of land owners to get the information as soon as we know the details.