(click to enlarge)
(click to enlarge)
Dwarf mistletoes (Arceuthobium spp.) are a common problem in Colorado
forests on ponderosa and lodgepole pine. Dwarf mistletoes are small,
leafless, parasitic flowering plants that grow into the phloem of trees.
Dwarf mistletoes kill by slowly robbing the tree of food and water.
Death occurs slowly in most cases and depends on the severity of infection
and on the vigor and size of the tree. (Jacobi and Swift, 2002).
The seeds, explosively discharged from the fruit at almost 60 mph, are
sticky and adhere to any surface they strike. Seeds that adhere to
young branches of susceptible trees germinate, and the mistletoe rootlet
penetrates the bark. Birds occasionally spread the seeds to uninfected
trees. Dwarf mistletoe seeds generally are dispersed in August and
early September. Mistletoes spread slowly from tree to tree.
(Jacobi and Swift, 2002).
There are eight species of mistletoes that affect all species of conifers
in the Rocky Mountains. Most dwarf mistletoes are considered species
or host specific, infecting only one particular species of tree and not
infecting others. In the Genesee community, Arceuthobium vaginatum,
the species that affects ponderosa pine (Pinus ponderosa), is the main
concern.
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