Parasitic Plants
From Bugwoodwiki
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Importance
Extensive infections and mortality are uncommon in ashes. However, infections occur typically in open-grown trees. This true mistletoe is used as greenery in Christmas decorations.
Identifying the Injury
Affected branches may be galled or swollen at the site of infection, and multiple infections may result in loss of growth. Branches beyond the mistletoe may be stunted or die back.
Identifying the Parasite
The mistletoe plant has stout, green stems and dark-green, leathery leaves. It is seen best in winter growing on major and minor branches and twigs of the host. The plant has opposite branching and inconspicuous flowers and produces white berries in the fall.
Biology
This perennial, evergreen plant grows as a parasite on tree branches. The seeds are covered with a sticky, gelatinous coating with and are spread by birds and small mammals. The seeds lodge on young branches and germinate. A rootlike, penetrating structure grows into the young branch and produces a mistletoe plant. One species, Phoradendron serotinum, affects many other broad-leaved trees in the South and East, but is limited by temperature in its northern range (Kansas to New Jersey). Several other species of Phoradendron occur in the West.
Control
Control normally is not needed in ashes, but pruning affected branches at least 30 cm below the point of infection may provide some control.
References
Solomon, J.D.; Leininger, T.D.; Wilson, A.D.; Anderson, R.L.; Thompson, L.C.; McCracken, F.I. 1993. Ash pests: A guide to major insects, diseases, air pollution injury and chemical injury. Gen. Tech. Rep. SO-96. New Orleans, LA: U.S. Department of Agriculture, Forest Service, Southern Forest Experiment Station. 45 p.
