Invasive_Species_Tech_Note_MT11 - United States Department...

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United States Department of Agriculture NATURAL RESOURCES CONSERVATION SERVICE Invasive Species Technical Note No. MT-11 April 2007 Ecology and Management of Perennial Pepperweed [ Lepidium latifolium L.] By Jim Jacobs, NRCS Invasive Species Specialist, Bozeman, Montana Jane Mangold, Restoration Ecologist, USDA, Agricultural Research Service, Burns, Oregon Figure 1. Perennial pepperweed infestation. Photo by Michael Carpinelli. Abstract Perennial pepperweed, also called tall whitetop and often confused with whitetop ( Cardaria draba ), is a rhizomatous perennial weed threatening riparian areas, irrigation ditches, and floodplain meadows in Montana. This weed in the mustard family (Brassicaceae) spreads by creeping roots and rhizomes, and prolific seed production. Found most often in seasonally flooded areas, perennial pepperweed can also spread to upland and rangeland sites, and it is adapted to salt-affected soils. It can form dense patches that compete with crops, forage plants, and riparian plants (see Figure 1). Infestations reduce crop yield and increase production costs, reduce livestock carrying capacity, and its control is costly. Perennial pepperweed is native to southeastern Europe and western Asia. The first record of perennial pepperweed in Montana is from Gallatin County in 1935 along a roadside near Manhattan. By 2002 it had been reported from 17 counties ( ) with a total of 2,750 acres infested. In Montana it has been found along roadways, railroads, the Missouri River, irrigation ditches, in winter wheat, alfalfa, Conservation Reserve Program, pastures, on dry hillsides, and in rangeland. Perennial pepperweed is ranked as a Category 2 noxious weed in Montana, meaning it is currently present and believed to be rapidly spreading from existing infestations. Perennial pepperweed can be temporarily suppressed using herbicides that contain metsulfuron, chlorsulfuron, or imazapic as active ingredients. Long-term herbicidal control requires repeated applications. Cattle, sheep, and goats will graze perennial pepperweed, but the effects on NRCS Montana Technical Note Invasive Species MT-11 1
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population fitness of long-term grazing with these animals are not known. Mowing and sheep grazing reduce stand density for up to one year. There are no approved biological control insects for release on perennial pepperweed. Biology and Ecology Roots. There are few white-flowered mustards that grow from creeping roots, therefore once it is established, this characteristic can help identify perennial pepperweed. The roots penetrate deeply into the soil and spread horizontally (see Figure 2). While roots can penetrate the soil to ten feet (2 m) or more, the majority of the root mass can be found in the upper two feet of the soil profile making perennial pepperweed competitive for soil moisture and nutrients. The roots are coarse with minimal development of fine roots or root hairs, are widely spaced, and form a
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This note was uploaded on 01/07/2010 for the course PLB 119 taught by Professor Rejmanek during the Spring '09 term at UC Davis.

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Invasive_Species_Tech_Note_MT11 - United States Department...

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