Perennial pepperweed
Lepidium latifolium

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Pictures of perennial pepperweed     Photo courtesy of:  http://tncweeds.ucdavis.edu/esadocs/lepilati.html

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Common names: broad-leaved peppergrass, tall whitetop, Virginia pepperweed, perennial pepperweed, broad-leaf peppergrass

Description: The perennial pepperweed is an aggressive weed that establishes and colonizes very fast.  It usually grows from 1 to 3 ft. and possibly up to 6 ft. tall.  The weed has white flowers that grow on top of the plant This weed was probably introduced into the United States around 1900 from contaminated beets.  This plant degrades the nesting area for wildlife and pushes them into other fields where there unwanted.  This noxious weed can tolerate salty soil very well and begins to infest very fast.  (1,2,3,4,5)

Habitat: Originally native to southern Europe and also to western Asia the pepperweed is now mostly known to grow on the west coast of the U.S.A.    (1,3,4,5)

Seeds:  Each plant produces a small waxy fruit that does not open but falls regularly during the winter season.  Each one of these little fruit bares 2 little seeds that are released when the fruit drops down from the plant.  The seeds that are dropped are round flattened and slightly hairy.  The measure in 1/16 of an inch in length and are reddish brown colored.  The perennial pepperweed can produce up too 6 billion seeds per acre. (1,2,5)

Leaves/Stems:  The waxy leaves are bright green to a gray waxy color.  The leaves on top may have smooth or toothed margins.  Stem leaves are larger and are stalked where upper leaves toward the top of the plant are shorter with shorter stalks.  The larger leaves can grow off the stem to up to 12 inches long.  All of the leaves have a noticeable white vein running through it. (1,2,3,4,5)

Roots:  Extended deep seeding roots that creep under the ground and are very deep seated.  The long extensive root system sends many shoots up in late winter or autumn and make a big web of the plant.  The roots do not hold soil together very well so they are known to be a problem or erosion on river banks, streams, and ditch banks. (1,5)

Flowers: Flowers occur on top of the plant in big dense clusters sitting on the very top of the weed.  Every flower has 4 sepals and 4 petals.  The seeds of this plant are carried in this plant and when this winter season comes when the flower is beginning to die away the seeds are dropped. (1,5)


Environments Favorable to Infestation:  It is known to be a problem on the roadsides, rangeland, field crop to riversides or on mountain tops. (1,4,5)


Chemical Control:  Glyphosate + 2,4-D was found to be 100% effective when applied to the pepperweed over a time of 3 months periodically.  The problem with this is that the glyphosate kills all perennial grasses with it so this means that all that grass that you have been growing for the last 2 or 3 years will be killed when you put this form of herbicide on your lawn. (2,4)


Cultural Control:  There is only 1 partially effective cultural control factor it is hand pulling and digging up.  Since the roots are very extensive it is crucial that you pull the plant before the plant has grown seeds.  Make sure that after the plant has been pulled that all roots have been removed or dug up. (1,2)

Links:

http://www.oneplan.org/Crop/noxWeeds/nxWeed19.htm
http://dnr.metrokc.gov/wlr/lands/weeds/peppweed.htm
http://www.agf.gov.bc.ca/cropprot/weedguid/pepperweed.htm
http://www.cdfa.ca.gov/phpps/ipc/weedmgtareas/MariposaMF/pepperweed.htm
http://www.nwcb.wa.gov/weed_info/pepperweed.html
http://www.yolorcd.org/weeds/pepperweed.shtml
http://www.extendinc.com/weedfreefeed/pepperweed.htm
http://www.wes.army.mil/el/pmis/plants/html/lepidium.html
http://ucce.ucdavis.edu/freeform/ceppc/documents/1995_Symposium_Proceedings1796.PDF
http://www.cwma.org/perr_pepperwood.html


Bibliography:

3.  Government of British Columbia, Field Guide to Noxious and Other Selected Weeds of British Columbia, (online) available, http://www.agf.gov.bc.ca/cropprot/weedguid/pepperweed.htm

4.  Fred Bentler, Perennial Pepperweed (Lepidium latifolium), (online), available, http://dnr.metrokc.gov/wlr/lands/weeds/peppweed.htm

5.  Yolo County Resource Conservation District, Perennial Pepperweed (Lepidium latifolium), (online), avaliable, http://www.yolorcd.org/weeds/pepperweed.shtml

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By:  Toby Marx and Jim Thorne 4/20/04

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