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. Diseased trees decline and die from the top down as lower infected branches take more 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 may 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 mistletoe that affect 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.

• Dwarf Mistletoe in Genesee
• Fact sheet from the Colorado State Forest Service
• Map of Dwarf Mistletoe Infestation in Genesee
• Mistletoe Operations on Open Space
• Mistletoe on Private Property
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