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Extension > Garden > Yard and Garden > Eastern spruce Dwarf Mistletoe

Eastern spruce Dwarf Mistletoe

Michelle Grabowski - University of Minnesota Extension Educator
Cynthia Ash Kanner - former University of Minnesota Extension Specialist

Back to Diseases of spruce trees in Minnesota

Eastern Spruce Dwarf Mistletoe

Photo by J.O'Brien USDA FS
Bugwood.org

Dwarf mistletoe is a parasitic plant (Arceuthobium pusillum) that most commonly attacks black spruce (Picea mariana) in northern Minnesota, although white spruce (Picea glauca) are also highly susceptible to the parasite. Dwarf mistletoe can also attack white pine, red pine, jack pine, eastern larch, balsam fir, and Colorado blue spruce. These trees are typically only infected with dwarf mistletoe when planted close to groups of spruce infected with the parasite.

Eastern Spruce Dwarf Mistletoe

Photo by J.O'Brien USDA FS
Bugwood.org

Identification

Eastern Spruce Dwarf Mistletoe

Photo by J.O'Brien USDA FS
Bugwood.org

Biology

Dwarf mistletoe is a parasitic plant that lives its entire life within the canopy of the tree. Female flowers shoot seeds, coated in a sticky layer, up to 55 feet away. Seeds can also stick to birds or other wildlife and be carried to trees much farther away. If these seeds land on a spruce branch, they germinate and colonize their new host. Root-like structures develop within the tree branches and rob the tree of nutrients and water. Witches' brooms develop on infected branches, and as the infection continues, the dwarf mistletoe continues to steal nutrients, and the spruce tree begins to decline. After 4-5 years the first dwarf mistletoe shoots appear on the infected spruce branches. These short (less than 1 inch) branches are yellow orange in color and have only small scale like leaves.

Management

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