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Dwarf Mistletoe

JETCO will again be spraying for Dwarf Mistletoe starting in July (prior to it going to seed around August 1st). Dwarf mistletoe is a parasitic plant that grows on the pine family of trees. It infects Ponderosa, Lodgepole and Douglas Fir. It sinks roots into the branches and trunk of a host tree, and draws its sustenance primarily from the host tree’s nutrients. It is eventually fatal to the tree. Once it gets into the tops of tall trees, dwarf mistletoe will infect and eventually kill any sapling within 40 to 50 feet of it, effectively preventing the trees from replacing themselves. Newly infected trees have a much better chance of being saved, but only if you stop the seeds from raining down on them from the infected trees surrounding them.

Ethephon, which is totally different than Carbaryl (Sevin) used for the pine beetle, is used and its primary objective is to stop trees infected with dwarf mistletoe from going to seed and infecting other trees. Ethephon will not kill the mistletoe, but will cause external shoots and fruits to dry up and fall off. It is not 100% effective. THIS IS STRICTLY AN OPTIONAL SPRAYING.

As with any disease, treatment involves trying to save an infected tree (or at least extend its life) while preventing that tree from infecting other trees. This is done by:

  • Aggressively pruning infected branches;
  • Removing badly infected small and intermediate trees and planting immune species to replace them;
  • Progressively removing large infected trees over a period of years as each reaches an advanced stage of infection; and
  • Spraying the remaining infected branches and whole trees with the chemical Ethephon to inhibit the seeding process.

Like marking for mountain pine beetle, the trees must be marked by tying flagging tape around the tree trunk. If you had mountain pine beetle spraying or pine beetle and Ips, please use a different color tape.