lepidium latifolium: a case study. what is lepidium latifolium?: semi-woody plant that grows in...

Lepidium latifolium: Lepidium latifolium: A A Case StudyCase Study

What is What is Lepidium Latifolium?:Lepidium Latifolium?:

Semi-woody plant that grows in Semi-woody plant that grows in dense masses of erect stemsdense masses of erect stems

Grows 1-3ft tall, but can grow up to Grows 1-3ft tall, but can grow up to 8ft tall in wet growing conditions8ft tall in wet growing conditions

Leaves and stems are waxyLeaves and stems are waxy Leaves are alternate with toothed to Leaves are alternate with toothed to

smooth blades (0.5 – 1.0 inches wide)smooth blades (0.5 – 1.0 inches wide) Flowers are a brilliant white, arranged Flowers are a brilliant white, arranged

in dense panicles in clusters of 6 to8. in dense panicles in clusters of 6 to8. (Young 1995)(Young 1995)

Common Names….Common Names….

WhitetopWhitetop Tall WhitetopTall Whitetop Broadleaf PeppergrassBroadleaf Peppergrass Broadleaf PepperwortBroadleaf Pepperwort Perennial PepperwortPerennial Pepperwort PepperwortPepperwort Virginia PepperweedVirginia Pepperweed

USDA (2008)USDA (2008)

Where is Where is Lepidium latifoliumLepidium latifolium from and where has it from and where has it naturalized to?naturalized to?

Native to Eurasia and Native to Eurasia and Northern AfricaNorthern Africa

Believed to have been Believed to have been accidentally introduced to accidentally introduced to North America as a North America as a contaminant in Sugar Beet contaminant in Sugar Beet seed (Young et al., 2005)seed (Young et al., 2005)

Has become naturalized in Has become naturalized in Australia, Mexico, Canada Australia, Mexico, Canada and the United Statesand the United States

Within the U.S. Within the U.S. Lepidium Lepidium latifolium latifolium has been has been declared a noxious weed in declared a noxious weed in 13 states and by the 13 states and by the Bureau of Land Bureau of Land Management (USDA, 2008)Management (USDA, 2008)

Figure 1: Distribution of Lep. L.throughout North America. (USDA, 2008)

Why is it considered invasive?Why is it considered invasive? Likes to establish near wetlands, Likes to establish near wetlands,

riverbanks, riparian areas and flood plains riverbanks, riparian areas and flood plains (Renz et al, 2004)(Renz et al, 2004)

Forms extremely dense clonal Forms extremely dense clonal monoculturesmonocultures

Has a tendency to out grow pre-existing Has a tendency to out grow pre-existing vegetation by:vegetation by:– Consuming available nutrients and moistureConsuming available nutrients and moisture– Forming a dense canopy where light cannot Forming a dense canopy where light cannot

penetratepenetrate Incredibly difficult to get rid of!Incredibly difficult to get rid of!

(Donaldson, 1997; Young et al., 1997)(Donaldson, 1997; Young et al., 1997)

What makes it invasive? What makes it invasive? There are several properties that make perennial There are several properties that make perennial

pepperweed a fierce competitorpepperweed a fierce competitor– Has high rate of dispersionHas high rate of dispersion

Reproduces by both seed and stoloniferous rhizomes; these Reproduces by both seed and stoloniferous rhizomes; these are generally carried by water to vulnerable downstream are generally carried by water to vulnerable downstream areas (Whitson et al., 1992; Donaldson, 1997)areas (Whitson et al., 1992; Donaldson, 1997)

Produces 15 billion seeds/ha; spread of seeds is facilitated Produces 15 billion seeds/ha; spread of seeds is facilitated by wind, animals, humans and vehicles (Eiswerth et al., by wind, animals, humans and vehicles (Eiswerth et al., 2005)2005)

– Has an extensive root systemHas an extensive root system Hypothesized that deep root system is what allows Hypothesized that deep root system is what allows

perennial peperweed to access water and gain a perennial peperweed to access water and gain a competitve advantage agiainst natives (Qualls et al., in competitve advantage agiainst natives (Qualls et al., in prep)prep)

– Has high phenotypic plasticity for survivalHas high phenotypic plasticity for survival Can tolerate shade, sun, and extensive flooding (Qualls et Can tolerate shade, sun, and extensive flooding (Qualls et

al., in prep)al., in prep)

Ecological Effects:Ecological Effects:

Influences soil properties and Influences soil properties and elemental cyclingelemental cycling– Blank et al., 2002Blank et al., 2002

Alters biogeochemical cycling so that Alters biogeochemical cycling so that affected sub soils are amelioratedaffected sub soils are ameliorated– Blank and Young, 2002Blank and Young, 2002

Ecological Effects: Perennial pepperweed Ecological Effects: Perennial pepperweed Influences soil properties and elemental cyclingInfluences soil properties and elemental cycling

In an experiment by Blank et.al. (2002) the effect of soil In an experiment by Blank et.al. (2002) the effect of soil nutrient depletion on the growth of and competition nutrient depletion on the growth of and competition between perennial pepperweed and between perennial pepperweed and Bromus tectorumBromus tectorum was was examinedexamined

Species were grown individually and in combinationSpecies were grown individually and in combination When the perennial pepperweed flowered, the roots and When the perennial pepperweed flowered, the roots and

aboveground mass of both species were harvested.aboveground mass of both species were harvested. Soils were then homogenized.Soils were then homogenized. Soil was re-planted with the same speciesSoil was re-planted with the same species This cycle was repeated for 3 growth cycles.This cycle was repeated for 3 growth cycles.


(Blank et al., 2002)(Blank et al., 2002) The Results:The Results:

– After 3 growth cycles the boveground mass of the After 3 growth cycles the boveground mass of the perennial pepperweed decreased significantly, and the perennial pepperweed decreased significantly, and the growth potential of the perennial pepperweed was growth potential of the perennial pepperweed was surpassed by that of the surpassed by that of the Bromus tectorumBromus tectorum

The Conclusion:The Conclusion:– The data suggests that, as nutrients are biocycled to the The data suggests that, as nutrients are biocycled to the

upper layers of the soil, the monoculture stands of upper layers of the soil, the monoculture stands of pepperweed may become nutrient limited and out-pepperweed may become nutrient limited and out-competed by plants with greater root densities.competed by plants with greater root densities.


Figure 2:Figure 2: Root/Shoot ratios Root/Shoot ratios of of Bromus TectorumBromus Tectorum and and Lepidium latifolium Lepidium latifolium after after each of three growth each of three growth cycles (Blank et al., 2002).cycles (Blank et al., 2002).

Ecological Effects: Perennial pepperweed alters biogeochemical Ecological Effects: Perennial pepperweed alters biogeochemical cycling so that affected sub soils are amelioratedcycling so that affected sub soils are ameliorated

(Blank and Young, 2002)(Blank and Young, 2002) Tested the hypothesis that perennial pepperweed Tested the hypothesis that perennial pepperweed

“alters biogeochemical cycling relative to pre-“alters biogeochemical cycling relative to pre-existing vegetation such that sodium affected existing vegetation such that sodium affected sub-soils are ameliorated”sub-soils are ameliorated”

Cycling and distribution of different elements Cycling and distribution of different elements were monitored for four years in sites that were were monitored for four years in sites that were both invaded with perennial pepperweed and both invaded with perennial pepperweed and sites that were not invaded but contained sites that were not invaded but contained Elytrigia elongataElytrigia elongata..

Ecological Effects: Perennial pepperweed alters Ecological Effects: Perennial pepperweed alters biogeochemical cycling so that affected sub soils are biogeochemical cycling so that affected sub soils are

amelioratedameliorated

(Blank and Young, 2002)(Blank and Young, 2002) The Results:The Results:

– Perennial pepperweed had significantly greater Perennial pepperweed had significantly greater concentrations of of C, Ca, Mg, K, and S in above ground concentrations of of C, Ca, Mg, K, and S in above ground tissue that tissue that Elytrigia elongataElytrigia elongata

– Perennial pepperweed was increasing the solubility of Perennial pepperweed was increasing the solubility of CaCa2+2+

The Conclusion:The Conclusion:– The increased solubility of CaThe increased solubility of Ca2+2+ lowered the ratio of lowered the ratio of

sodium adsorption to the soil, and ameliorated the soils sodium adsorption to the soil, and ameliorated the soils by “decreasing dispersion, increasing aggregation [of by “decreasing dispersion, increasing aggregation [of sodium] and improving physical properties.sodium] and improving physical properties.

– Once sodic soils are ameliorated they will likely be able Once sodic soils are ameliorated they will likely be able to support a richer and more productive community, if to support a richer and more productive community, if perennial pepperweed can be controlled.perennial pepperweed can be controlled.

Ecological Effects: Perennial pepperweed alters Ecological Effects: Perennial pepperweed alters biogeochemical cycling so that affected sub soils are biogeochemical cycling so that affected sub soils are

amelioratedameliorated

Figure 3:Figure 3: Biogeochemical Biogeochemical fluxes of C, Ca, Mg, K, and S fluxes of C, Ca, Mg, K, and S in in Elytrigia elongataElytrigia elongata and and Lepidium latifoliumLepidium latifolium and and calculated SAR (sodium calculated SAR (sodium adsorption ratios). (Blank and adsorption ratios). (Blank and Young, 2002)Young, 2002)

Immiscibly displaced Immiscibly displaced (aqueous-soluble) Mg+2, (aqueous-soluble) Mg+2, Ca+2, Na+, K+, and SO4-2 Ca+2, Na+, K+, and SO4-2 and and sodium adsorption sodium adsorption ratio (SAR) calculated from ID ratio (SAR) calculated from ID values, by plant (Lepidium values, by plant (Lepidium latifolium community vs latifolium community vs Elytrigia elongata community) Elytrigia elongata community) and soil depth. Bars are + 1 and soil depth. Bars are + 1 standard error.standard error.

ControlControl Very difficult to control through mechanical Very difficult to control through mechanical

methodsmethods– Deep tap roots, rhizomenous regenerationDeep tap roots, rhizomenous regeneration

Very difficult to control through Chemical Very difficult to control through Chemical methodsmethods– Waxy layer of cutin that protects leaves and stemsWaxy layer of cutin that protects leaves and stems– Perennial pepperweed generally grows by water. Only Perennial pepperweed generally grows by water. Only

two herbicides are safe for use by water two herbicides are safe for use by water andand affective affective against broadleaf vegetationagainst broadleaf vegetation

Glyphosate (N-Phosphonomethylglycine)Glyphosate (N-Phosphonomethylglycine) 2,4-D (2,4-dichlorophenoxy acetic acid) 2,4-D (2,4-dichlorophenoxy acetic acid)

No existing mechanisms for biological controlNo existing mechanisms for biological control

Control- tilling and herbicidesControl- tilling and herbicides In experiments by Young et al. (1998) control of In experiments by Young et al. (1998) control of

perennial pepperweed was examined through use perennial pepperweed was examined through use of tilling and herbicides over wide range of soils, of tilling and herbicides over wide range of soils, over a 2 year period.over a 2 year period.

ResultsResults– Tillage with periodic disking had no permanent affectTillage with periodic disking had no permanent affect– Applications of 2,4-D and Glyphosate had no permanent Applications of 2,4-D and Glyphosate had no permanent

affectaffect– Applications of Chlorsulfuron was effective in destroying Applications of Chlorsulfuron was effective in destroying

the perennial pepperweed; 3 years after the initial the perennial pepperweed; 3 years after the initial application, the plants had not re-establishedapplication, the plants had not re-established

Control – mowing and herbacidesControl – mowing and herbacides

In a study performed by Renz and In a study performed by Renz and DiTomaso (2004) it was demonstrated that DiTomaso (2004) it was demonstrated that perennial pepperweed could potentially be perennial pepperweed could potentially be controlled by mowing followed by an controlled by mowing followed by an application of Glyphosateapplication of Glyphosate

– Mowed plants translocated more glyphosate Mowed plants translocated more glyphosate from their basal leaves to their below ground from their basal leaves to their below ground tissue than un-mowed plantstissue than un-mowed plants

Mowed plants accumulated 6.7% of glyphosateMowed plants accumulated 6.7% of glyphosate Unmowed plants only accumulated .38% of Unmowed plants only accumulated .38% of

glyphosateglyphosate

Control – mowing and herbacidesControl – mowing and herbacides

Table 1Table 1: Average percent : Average percent 1414C-glyphosate C-glyphosate recovered in various tissues of perennial recovered in various tissues of perennial pepperweed 48 hours after labeling (Renz et al., pepperweed 48 hours after labeling (Renz et al., 2004)2004)

Control - FloodingControl - Flooding

Study by Qualls et al. (in prep)Study by Qualls et al. (in prep) When perennial pepperweed was When perennial pepperweed was

subjected to 3 months of flooding, with subjected to 3 months of flooding, with water above the plant tops the following water above the plant tops the following ocurred…ocurred…– Rapid die back of above gound tissueRapid die back of above gound tissue– 17% of the root stock survived to re-sprout 17% of the root stock survived to re-sprout

after the soil was drainedafter the soil was drained Conclusion:Conclusion:

– Perennial pepperweed appears to have a wide Perennial pepperweed appears to have a wide range of tolerance for survivalrange of tolerance for survival

Control- Mowing and grazing by Control- Mowing and grazing by sheepsheep

In a study conducted by Allen et al. (2001) Sheep In a study conducted by Allen et al. (2001) Sheep grazing and mowing were both examined as grazing and mowing were both examined as methods for the control of perennial pepperweed.methods for the control of perennial pepperweed.

Infested pastures were mowed or grazed for one Infested pastures were mowed or grazed for one seasonseason

Results:Results:– Pastures that had been grazed by sheep had a reduction Pastures that had been grazed by sheep had a reduction

in perennial pepperweed of 78%in perennial pepperweed of 78%– Pasures that had been mowed had a reduction of 48%Pasures that had been mowed had a reduction of 48%– These results are contrary to grazing experiments using These results are contrary to grazing experiments using

goats (Young et.al.,2000) goats (Young et.al.,2000)

Control- Mowing and grazing by Control- Mowing and grazing by sheepsheep

Figure 4Figure 4: Change in number of perennial pepperweed : Change in number of perennial pepperweed plants in mowed and grazed pastures after one season. plants in mowed and grazed pastures after one season. (Allen, 2001).(Allen, 2001).

Economic and Social ImpactsEconomic and Social Impacts A dynamic cost-benefit analysis for the control of A dynamic cost-benefit analysis for the control of

perennial pepperweed was performed by perennial pepperweed was performed by Eiswerth et al. (2005)Eiswerth et al. (2005)– Costs and benefits for land that was used solely for Costs and benefits for land that was used solely for

grazing and for land that was used for both grazing and grazing and for land that was used for both grazing and hay harvest were estimated by analyzing current costs hay harvest were estimated by analyzing current costs for weed control (Table 2), estimated future control for weed control (Table 2), estimated future control costs, future forgone revenues, and by calculating the costs, future forgone revenues, and by calculating the standardized benefits and costs for infested land.standardized benefits and costs for infested land.

Results:Results:– On land that is used for grazing only, it would take 15 On land that is used for grazing only, it would take 15

years for the costs to equal the returns.years for the costs to equal the returns.– On land that is used for both grazing and hay, it would On land that is used for both grazing and hay, it would

take 5-6 years for the costs of control to equal the take 5-6 years for the costs of control to equal the returnsreturns

Economic and Social ImpactsEconomic and Social Impacts Table 2:Table 2: Predicted costs Predicted costs

for weed control (Eiswerth for weed control (Eiswerth et.al. 2005). et.al. 2005).

Economic and Social ImpactsEconomic and Social Impacts Figure 5Figure 5: Predicted costs and foregone net revenues for infested land. L1, cumulative foregone net : Predicted costs and foregone net revenues for infested land. L1, cumulative foregone net

hay harvest and grazing revenue at 30% weed expansion rate; L2, cumulative foregone net hay hay harvest and grazing revenue at 30% weed expansion rate; L2, cumulative foregone net hay harvest and grazing revenue at 15% weed expansion rate; L3, cumulative foregone net grazing-only harvest and grazing revenue at 15% weed expansion rate; L3, cumulative foregone net grazing-only revenue at 30% expansion rate; L4, cumulative foregone net grazing-only revenue at 15% revenue at 30% expansion rate; L4, cumulative foregone net grazing-only revenue at 15% expansion rate; C1, cumulative cost to control the infestation at 70% control rate; C2, cumulative expansion rate; C1, cumulative cost to control the infestation at 70% control rate; C2, cumulative cost to control the infestation at 80% control rate; C3, cumulative cost to control the infestation at cost to control the infestation at 80% control rate; C3, cumulative cost to control the infestation at 90% control rate (Eiswerth et.al.2005)90% control rate (Eiswerth et.al.2005)

ConclusionsConclusions Perennial pepperweed is very difficult to control; at the Perennial pepperweed is very difficult to control; at the

moment it is hopeless for eradicationmoment it is hopeless for eradication It should have become a top priority for eradication 30 to It should have become a top priority for eradication 30 to

40 years ago40 years ago May still be possible to thwart the continued spread of May still be possible to thwart the continued spread of

Perennial pepperweed through education, prevention, rapid Perennial pepperweed through education, prevention, rapid response, and diligence in monitoring and treatmentresponse, and diligence in monitoring and treatment

Hopefully an effective bio-control agent will be found!Hopefully an effective bio-control agent will be found! Or, perennial pepperweed may eventually eradicate itself Or, perennial pepperweed may eventually eradicate itself

through its currently observed patterns of nutrient cyclingthrough its currently observed patterns of nutrient cycling However! If I were to recommend a treatment for control, I However! If I were to recommend a treatment for control, I

would recommend a regiment that consists of grazing by would recommend a regiment that consists of grazing by sheep and mowing for areas that are accessible to sheep and mowing for areas that are accessible to livestock. For areas that are inaccessible by livestock, livestock. For areas that are inaccessible by livestock, would recommend a treatment of mowing/weed-wacking would recommend a treatment of mowing/weed-wacking followed by glyphosate spot application.followed by glyphosate spot application.

ReferencesReferences Allen JR, Holcombe DW, Hanks DR, Surian M, McFarland M, Bruce LB, Johnson W, Allen JR, Holcombe DW, Hanks DR, Surian M, McFarland M, Bruce LB, Johnson W,

Fernandez G (2001) Effects of sheep grazing and mowing on the control of Fernandez G (2001) Effects of sheep grazing and mowing on the control of perennial pepperweed (perennial pepperweed (Lepidium latifoliumLepidium latifolium). American Society of Animal ). American Society of Animal Science Science 5252

Blank RR, Young JA (2002) Influence of the exotic invasive cruciferBlank RR, Young JA (2002) Influence of the exotic invasive crucifer Lepidium Lepidium latifoliumlatifolium, , on soil properties and elemental cycling. Soil Science167:821-829on soil properties and elemental cycling. Soil Science167:821-829

Blank RR, Qualls RG, Young JA (2002) Blank RR, Qualls RG, Young JA (2002) Lepidium latifoliumLepidium latifolium: plan nutrient competition-: plan nutrient competition-soil interactions. Biol. Fertile Soils 35:458-464soil interactions. Biol. Fertile Soils 35:458-464

Birdsall JL, Quimby PC, Svejcar TJ, Young JA (1997) Potential for Biological Control Birdsall JL, Quimby PC, Svejcar TJ, Young JA (1997) Potential for Biological Control of of Perennial Pepperweed (Perennial Pepperweed (Lepidium latifoliumLepidium latifolium))

Chen H, Qualls RG, Miller GC (2002) Adaptive responses of Chen H, Qualls RG, Miller GC (2002) Adaptive responses of Lepidium Lepidium latifolium to soil latifolium to soil flooding: biomass allocation, aerenchyma formation, adventitious rooting and flooding: biomass allocation, aerenchyma formation, adventitious rooting and ethylene production. Environmental and Experimental Botony 48: 119-128ethylene production. Environmental and Experimental Botony 48: 119-128

Donaldson, SG (1997) Flood-Borne Noxious Weeds: Impacts on Riparian Areas and Donaldson, SG (1997) Flood-Borne Noxious Weeds: Impacts on Riparian Areas and Wetlands. California Exotic Pest Plant Council; 1997 Symposium ProceedingsWetlands. California Exotic Pest Plant Council; 1997 Symposium Proceedings

Eiswerth ME, Singletary L, Zimmerman JR, Johnson WS (2005) Dynamic Benefit-Cost Eiswerth ME, Singletary L, Zimmerman JR, Johnson WS (2005) Dynamic Benefit-Cost analysis for Controlling Perennial Pepperweed (analysis for Controlling Perennial Pepperweed (Lepidium latifoliumLepidium latifolium): A Case ): A Case Study. Weed Technology 19:237-243Study. Weed Technology 19:237-243

Lipa JJ (1974) Survey and Study of Insects Associated with Cruciferous Plants in Poland Lipa JJ (1974) Survey and Study of Insects Associated with Cruciferous Plants in Poland and Surrounding Countries: Final Report. Inst. Of Plant Prot., Lab. Of Biol. and Surrounding Countries: Final Report. Inst. Of Plant Prot., Lab. Of Biol. Contr., Miczurina 20, Poznan, Poland, 310ppContr., Miczurina 20, Poznan, Poland, 310pp

Qualls JR, Walker M (In preparation) Competition for Water by Tall WhitetopQualls JR, Walker M (In preparation) Competition for Water by Tall Whitetop

References Continued…References Continued… Renz MJ, DiTomaso JM (2004) Mechanism for the enhanced effect of Renz MJ, DiTomaso JM (2004) Mechanism for the enhanced effect of

mowing followed by glyphosate application to re-sprouts of mowing followed by glyphosate application to re-sprouts of perennial perennial pepperweed (pepperweed (Lepidium latifoliumLepidium latifolium). Weed Science ). Weed Science 52:14-52:14- 2323

United States Department of Agriculture (2008) Plants Profile: United States Department of Agriculture (2008) Plants Profile: Lepidium Lepidium latifolium.latifolium.http://plants.usda.gov/java/profile?symbolhttp://plants.usda.gov/java/profile?symbol=LELA2=LELA2, ,

November 18, 2008.November 18, 2008. Whitson TD, Burrill LC, Dewey SA, Cudney DW, Nelson BE, Lee RD, Parker Whitson TD, Burrill LC, Dewey SA, Cudney DW, Nelson BE, Lee RD, Parker

R (1992) Weeds of the West. Western Society of Weed R (1992) Weeds of the West. Western Society of Weed Science. Newark, CA, 630ppScience. Newark, CA, 630pp

Young, JA (1995) Perennial Pepperweed. Rangelands 17:121-123Young, JA (1995) Perennial Pepperweed. Rangelands 17:121-123 Young JA,Palmquist DE, Wotring SO (1997) The invasive nature of Young JA,Palmquist DE, Wotring SO (1997) The invasive nature of

Lepidium Lepidium latifoliumlatifolium: a review. Plant Invasions: studies from North : a review. Plant Invasions: studies from North America and Europe p. 59-68. Leiden, Netherlands : America and Europe p. 59-68. Leiden, Netherlands : BackhuysBackhuys

Young JA, Palmquist DE, Blank RR (1998) The Ecology and control of Young JA, Palmquist DE, Blank RR (1998) The Ecology and control of Perennial Perennial Pepperweed. Weed Technology 12:402-405Pepperweed. Weed Technology 12:402-405

Young JA, (1999) Young JA, (1999) Lepidium latifoliumLepidium latifolium L. ecology and control. USDA, L. ecology and control. USDA, Agricultural Research Service. National Symposium on Tall Agricultural Research Service. National Symposium on Tall Whitetop-Whitetop-1999, Alamosa, Colorado. pp. 43-45.1999, Alamosa, Colorado. pp. 43-45.

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