Nutsedge (Cyperus spp.) Biology: Implications For Management Dr. Theodore M. Webster Crop Protection...

Nutsedge (Nutsedge (Cyperus Cyperus spp.) Biology:spp.) Biology:Implications For ManagementImplications For Management

Dr. Theodore M. WebsterDr. Theodore M. WebsterCrop Protection and Management Research UnitCrop Protection and Management Research Unit

USDA-ARSUSDA-ARS

Tifton, GATifton, GA

The Cyperaceae FamilyThe Cyperaceae Family• Cyperaceae or the Sedges include 17 Cyperaceae or the Sedges include 17

different generadifferent genera

• Those species most commonly viewed as Those species most commonly viewed as troublesome weeds are found in the troublesome weeds are found in the CyperusCyperus genus. genus.

• Of the 45 Of the 45 CyperusCyperus species in the species in the Southeast U.S., 29 are perennialsSoutheast U.S., 29 are perennials

• There are two primary perennial There are two primary perennial CyperusCyperus spp. that cause economic losses.spp. that cause economic losses.

Nutsedges: Important Crops or Nutsedges: Important Crops or Important Weeds?Important Weeds?

• Purple nutsedge tubers were a staple in a Purple nutsedge tubers were a staple in a late-Paleolithic (~16,000 B.C.) in Egypt.late-Paleolithic (~16,000 B.C.) in Egypt.

• Egyptian tombs dating to the 15Egyptian tombs dating to the 15thth Century B.C. have been found to have Century B.C. have been found to have recipes for ground tiger nuts (aka recipes for ground tiger nuts (aka nutsedge tubers) mixed with honey.nutsedge tubers) mixed with honey.

• Theophrastus (d. 287 B.C.): Egyptians Theophrastus (d. 287 B.C.): Egyptians boiled yellow nutsedge tubers in beerboiled yellow nutsedge tubers in beer

Negbi 1992Negbi 1992

Nutsedges: Important WeedsNutsedges: Important Weeds

• Purple nutsedge: identified as a weed Purple nutsedge: identified as a weed growing in cropland areas in 1growing in cropland areas in 1stst Century Century A.D.A.D.

• Purple nutsedge is considered the Purple nutsedge is considered the World’s Worst Weed.World’s Worst Weed.

• Yellow nutsedge is one of the Top 5 Yellow nutsedge is one of the Top 5 World’s Worst Weeds.World’s Worst Weeds.

Negbi 1992Negbi 1992 Holm et al. 1977Holm et al. 1977

Southern Weed Science Society Weed GuideSouthern Weed Science Society Weed Guide

• Yellow Nutsedge Yellow Nutsedge

• ((Cyperus esculentusCyperus esculentus L.) L.)

• Cold tolerance: 95% of Cold tolerance: 95% of tubers survived 2 C for 12 tubers survived 2 C for 12 weeks when buried at 10 cmweeks when buried at 10 cm

• Distributed in areas where Distributed in areas where soil freezessoil freezes

• Purple Nutsedge Purple Nutsedge

• ((Cyperus rotundusCyperus rotundus L.) L.)

• Cold Intolerance: <10% of Cold Intolerance: <10% of tubers survived 2 C for 12 tubers survived 2 C for 12 wks at 10 cmwks at 10 cm

• Distributed in areas where Distributed in areas where soil freezes infrequentlysoil freezes infrequently

Stoller 1973Stoller 1973

A Discussion of Nutsedges:A Discussion of Nutsedges:

• A tale of two tubers: why are nutsedges A tale of two tubers: why are nutsedges such persistent weeds?such persistent weeds?

• A nutsedge is a nutsedge is a nutsedge?

• 1 tuber then 10 tubers then 1000 tubers

• How do I get rid of my nutsedges?

• Are all mulches created equal?

• Solarization: fact or fiction?

Why are nutsedges Why are nutsedges such persistent such persistent weed problems?weed problems?

• Estimated half life of a Purple Nutsedge tuber Estimated half life of a Purple Nutsedge tuber is 16 monthsis 16 months

• Predicted longevity of a tuber is 42 monthsPredicted longevity of a tuber is 42 months

• Burial at 8 and 23 cm did not affect tuber Burial at 8 and 23 cm did not affect tuber dormancy/viabilitydormancy/viability

Neeser et al. 1997Neeser et al. 1997

Persistence: Tubers or Seeds?Persistence: Tubers or Seeds?• Purple nutsedge samples showed very Purple nutsedge samples showed very

limited intraspecific variation (RAPD).limited intraspecific variation (RAPD).– Seeds were produced, but none germinated.Seeds were produced, but none germinated.

• Yellow nutsedge samples showed a wide Yellow nutsedge samples showed a wide range of variation.range of variation.– 17% of the flowers produced seed.17% of the flowers produced seed.– Viable seed produced 2 wks after full bloom.Viable seed produced 2 wks after full bloom.– 78% of the seed germinated.78% of the seed germinated.– Field studies indicate only 0.78% of seed Field studies indicate only 0.78% of seed

established into a plant.established into a plant.

Okoli et al. 1997Okoli et al. 1997 Thullen and Keeley 1979Thullen and Keeley 1979Lapham and Drennan 1990Lapham and Drennan 1990

When Do Tubers Start to Form?When Do Tubers Start to Form?

• Tuber initiation: 6 to 8 Tuber initiation: 6 to 8 WWeeks eeks AAfter fter FFoliar oliar EEmergence (same time as flowering).mergence (same time as flowering).

• Underground structures have more biomass Underground structures have more biomass than the aboveground foliage by 6 WAFE.than the aboveground foliage by 6 WAFE.

• Tuber chains formed by 10 WAFE.Tuber chains formed by 10 WAFE.

• Long days stimulate: shoot, root, and rhizomes Long days stimulate: shoot, root, and rhizomes

• Short days stimulate: tuber and floral Short days stimulate: tuber and floral production.production.

Hauser 1962Hauser 1962 Williams 1982Williams 1982

Reproductive Success!Reproductive Success!• Purple nutsedge planted at 1-ft intervals Purple nutsedge planted at 1-ft intervals

(43,560 plants/acre) produced in 1 season:(43,560 plants/acre) produced in 1 season:– 3,090,000 plants/acre 3,090,000 plants/acre

– 4,442,000 tubers and bulbs/acre 4,442,000 tubers and bulbs/acre

• Cultivation in the second season did not affect Cultivation in the second season did not affect the number of tubers and bulbs. the number of tubers and bulbs.

• Heavy shading (72% shade) during the second Heavy shading (72% shade) during the second growing season reduced tuber and bulb growing season reduced tuber and bulb formation.formation.

Hauser 1962Hauser 1962

Yellow Nutsedge Yellow Nutsedge

Tubers:Tubers: From 1 tuber From 1 tuber

700 tubers 700 tubers

produced afterproduced after

6 Months of 6 Months of

GrowthGrowth

Competition for LightCompetition for Light

• Yellow nutsedge appears to be more Yellow nutsedge appears to be more tolerant of shade than Purple nutsedgetolerant of shade than Purple nutsedge– Yellow nutsedge biomass in 30% shade was Yellow nutsedge biomass in 30% shade was

not different than in full sunlight.not different than in full sunlight.– Purple nutsedge biomass was reduced in a Purple nutsedge biomass was reduced in a

linear with light.linear with light.

• Yellow nutsedge has a lower light Yellow nutsedge has a lower light compensation point (84 µmol mcompensation point (84 µmol m-2-2 s s-1-1) than ) than purple nutsedge (127 µmol mpurple nutsedge (127 µmol m-2-2 s s-1-1).).

Santos et al. 1997Santos et al. 1997Jordan-Molero and Stoller 1978Jordan-Molero and Stoller 1978


A tale of two tubers

• A nutsedge is a nutsedge is a nutsedge? A nutsedge is a nutsedge is a nutsedge? Or How can I distinguish these species?Or How can I distinguish these species?

• 1 tuber then 10 tubers then 1000 tubers




YELLOW NUTSEDGE:YELLOW NUTSEDGE: - Yellow florets- Yellow florets - Blades: lighter green- Blades: lighter green

PURPLE NUTSEDGE:PURPLE NUTSEDGE: - Dark red/purple florets- Dark red/purple florets - Blades: deeper green- Blades: deeper green

PURPLE NUTSEDGEPURPLE NUTSEDGEblade has a short, blade has a short,

abrupt tipabrupt tip

YELLOW NUTSEDGE: YELLOW NUTSEDGE: blade has a long, blade has a long,

drawn-out tipdrawn-out tip

Three-RankedThree-Ranked

Triangular-ShapedTriangular-Shaped

Taster’s ChoiceTaster’s Choice

PURPLE NUTSEDGEPURPLE NUTSEDGEYELLOW NUTSEDGE YELLOW NUTSEDGE

Purple Nutsedge: Tuber ChainsPurple Nutsedge: Tuber Chains

Yellow Nutsedge: Tubers Yellow Nutsedge: Tubers directly attached directly attached to mother plantto mother plant


A tale of two tubersA nutsedge is a nutsedge is a nutsedge?

• 1 tuber then 10 tubers then 1000 tubers1 tuber then 10 tubers then 1000 tubers




YELLOW NUTSEDGEYELLOW NUTSEDGEPURPLE NUTSEDGEPURPLE NUTSEDGE

Objective: Evaluate the Objective: Evaluate the Spatial Dynamics of Spatial Dynamics of Yellow and Purple Yellow and Purple

Nutsedge Nutsedge Expansion After 3 and 6 Expansion After 3 and 6 Months (From a Single Months (From a Single

Planted Tuber)Planted Tuber)

Yellow NutsedgeYellow Nutsedge

Purple NutsedgePurple Nutsedge

0 1 2 3 40

1

2

3

4

Yellow Nutsedge Yellow Nutsedge Patch Expansion:Patch Expansion:

6 months of growth 6 months of growth from a single tuberfrom a single tuber

Each Tick = 12.7 cmEach Tick = 12.7 cmScale 0 to 0.5 mScale 0 to 0.5 m

Eac

h T

ick

= 1

2.7

cmE

ach

Tic

k =

12.

7 cm

Sca

le 0

to

0.5

mS

cale

0 t

o 0.

5 m

Patch Area: 0.18 mPatch Area: 0.18 m22

177 Yellow Nutsedge Shoots177 Yellow Nutsedge ShootsMax. Density: 7000 shoots/mMax. Density: 7000 shoots/m22

0 4 8 12 160

3

6

9

12

15

18

21

24

27

30

33

Purple Nutsedge Purple Nutsedge Patch Expansion:Patch Expansion:

6 months of growth 6 months of growth from a single tuberfrom a single tuber


Eac

h T

ick

= 1

2.7

cmE

ach

Tic

k =

12.

7 cm

Sca

le 0

to

4.2

mS

cale

0 t

o 4.

2 m

Patch Area: 7.85 mPatch Area: 7.85 m22

518 Purple Nutsedge Shoots518 Purple Nutsedge ShootsMax. Density: 280 shoots/mMax. Density: 280 shoots/m22

0 4 8 12 160

3

6

9

12

15

18

21

24

27

30

33

0 4 8 12 160

3

6

9

12

15

18

21

24

27

30

33


Eac

h T

ick

= 1

2.7

cmE

ach

Tic

k =

12.

7 cm

Sca

le 0

to

4.2

mS

cale

0 t

o 4.

2 m

Eac

h T

ick

= 1

2.7

cmE

ach

Tic

k =

12.

7 cm

Sca

le 0

to

4.2

mS

cale

0 t

o 4.

2 m


Yellow NutsedgeYellow Nutsedge Purple NutsedgePurple Nutsedge

7.85 m7.85 m220.18 m0.18 m22

Preliminary ConclusionsPreliminary Conclusions

• Purple nutsedge produced:Purple nutsedge produced:– Similar number of shoots at 3 monthsSimilar number of shoots at 3 months– 2-fold more shoots than did yellow nutsedge 2-fold more shoots than did yellow nutsedge

at 6 monthsat 6 months

• Purple nutsedge expanded to a patch size Purple nutsedge expanded to a patch size 31-fold greater than yellow nutsedge31-fold greater than yellow nutsedge

• Yellow Nutsedge does not distribute itself Yellow Nutsedge does not distribute itself far from the mother tuberfar from the mother tuber

Take Home Message?Take Home Message?

• Confirms the predictions of a spatial Confirms the predictions of a spatial model of yellow nutsedge growth: model of yellow nutsedge growth: farming operations are the main cause farming operations are the main cause of yellow nutsedge dispersal in the field of yellow nutsedge dispersal in the field (Schippers et al. 1993).(Schippers et al. 1993).

• Purple nutsedge is well suited to Purple nutsedge is well suited to distribute itself through its environment.distribute itself through its environment.


A tale of two tubersA nutsedge is a nutsedge is a nutsedge?1 tuber then 10 tubers then 1000 tubers

• How do I get rid of my nutsedges? How do I get rid of my nutsedges? Herbicides and FumigantsHerbicides and Fumigants



Yellow Nutsedge: 80% Emergence byYellow Nutsedge: 80% Emergence by 6 May 1999 and 30 April 20006 May 1999 and 30 April 2000

Purple Nutsedge: 80% Emergence byPurple Nutsedge: 80% Emergence by 1 June 1999 and 21 May 20001 June 1999 and 21 May 2000

Can We Predict Nutsedge Emergence?Can We Predict Nutsedge Emergence?

Herbicides and Nutsedge ControlHerbicides and Nutsedge Control• Yellow NutsedgeYellow Nutsedge

– Bentazon (75%)Bentazon (75%)

– Metolachlor (55-75%)Metolachlor (55-75%)

– Glyphosate (55%)Glyphosate (55%)

– Halosulfuron (95%)Halosulfuron (95%)

– Imazapic (80%)Imazapic (80%)

– Imazethapyr (60%)Imazethapyr (60%)

– Fomesafen Fomesafen • PRE (85%)PRE (85%)

• POST (60%)POST (60%)

– MSMA MSMA • 1 lb ai/A (45%)1 lb ai/A (45%)

• 2 lb ai/A (90%)2 lb ai/A (90%)

• Purple NutsedgePurple Nutsedge– Bentazon (20%)Bentazon (20%)

– Metolachlor (<20%)Metolachlor (<20%)

– Glyphosate (70%)Glyphosate (70%)

– Halosulfuron (95%)Halosulfuron (95%)

– Imazapic (90%)Imazapic (90%)

– Imazetheapyr (70%)Imazetheapyr (70%)

– Fomesafen Fomesafen • PRE (35%)PRE (35%)

• POST (?)POST (?)

– MSMA MSMA • 1 lb ai/A (30%)1 lb ai/A (30%)

• 2 lb ai/A (65%)2 lb ai/A (65%)

Purple Nutsedge and GlyphosatePurple Nutsedge and Glyphosate

• Purple nutsedge Purple nutsedge control was not control was not improved when improved when glyphosate was tank glyphosate was tank mixed with:mixed with:– chlorimuronchlorimuron

– imazaquinimazaquin

– pyrithiobacpyrithiobac

Rao and Reddy 1999Rao and Reddy 1999

• Glyphosate at 1.0 kg/ha Glyphosate at 1.0 kg/ha required 72 hrs to required 72 hrs to translocate to the translocate to the tuber.tuber.

• Glyphosate at 2.0 kg/ha Glyphosate at 2.0 kg/ha required 36 hrs.required 36 hrs.

• Glyphosate kills foliage Glyphosate kills foliage and tubers directly and tubers directly attached to treated attached to treated plants.plants.

Rain, Rain Go AwayRain, Rain Go Away

• Simulated rainfall at 1 and 24 hours Simulated rainfall at 1 and 24 hours reduced glyphosate efficacy on purple reduced glyphosate efficacy on purple nutsedge 50 and 33%, respectively.nutsedge 50 and 33%, respectively.

• A rain-free period of 72 hours was A rain-free period of 72 hours was needed to avoid loss of glyphosate needed to avoid loss of glyphosate activity.activity.

Bariuan et al. 1999Bariuan et al. 1999

Quick Burn! Control?Quick Burn! Control?

• Paraquat will quickly dessicate foliage Paraquat will quickly dessicate foliage and stop new tuber production, however and stop new tuber production, however the effects are temporary as new shoots the effects are temporary as new shoots will emerge from the tuber (Pereira et al. will emerge from the tuber (Pereira et al. 1987).1987).

Take Home Message?Take Home Message?

• Which nutsedge do you have?Which nutsedge do you have?

• Herbicide efficacy is often rate dependent; Herbicide efficacy is often rate dependent; crop tolerance, weed efficacy, and crop tolerance, weed efficacy, and economics dictate herbicide rate.economics dictate herbicide rate.

• There are no quick fixes with nutsedges - There are no quick fixes with nutsedges - Management of nutsedge species is a Management of nutsedge species is a multi-year process.multi-year process.

Fumigants and Nutsedge PopulationsFumigants and Nutsedge Populations• Methyl Bromide: Methyl Bromide:

* 74 to 100% reduction in nutsedge numbers 74 to 100% reduction in nutsedge numbers through plastic compared to UTCthrough plastic compared to UTC

• (1,3-dichloropropene + Chloropicrin + (1,3-dichloropropene + Chloropicrin + Metham Sodium) and (Methyl Iodide):Metham Sodium) and (Methyl Iodide):* Early: 76% and 91% ReductionEarly: 76% and 91% Reduction* Late: 22% and 21% IncreaseLate: 22% and 21% Increase

• 1,3-dichloropropene + Chloropicrin: 1,3-dichloropropene + Chloropicrin: (Inconsistent results)(Inconsistent results)* 90%90%++ Reduction in 1998 Reduction in 1998* 12% Reduction and 120% Increase in 199912% Reduction and 120% Increase in 1999

Webster et al. 2001Webster et al. 2001


A tale of two tubersA nutsedge is a nutsedge is a nutsedge?1 tuber then 10 tubers then 1000 tubersHow do I get rid of my nutsedges?

• Are all mulches created equal?Are all mulches created equal?


Nontreated Control:Nontreated Control:Polyethylene MulchPolyethylene Mulch

Nontreated Control:Nontreated Control:Bare GroundBare Ground

NutsedgeNutsedge CrowfootgrassCrowfootgrassPolyethylene Polyethylene mulch mulch suppresses suppresses weed growth, weed growth, but creates a but creates a niche for niche for nutsedgesnutsedges

• Black plastic: 11% of yellow nutsedge Black plastic: 11% of yellow nutsedge shoots punctured and emerged through; shoots punctured and emerged through; tubers were produced.tubers were produced.

• Clear plastic: yellow nutsedge shoots did Clear plastic: yellow nutsedge shoots did not puncture; caused yield reduction; not puncture; caused yield reduction; tubers were produced.tubers were produced.

• IRT plastic: suppressed yellow nutsedge IRT plastic: suppressed yellow nutsedge emergence; prevented tuber production. emergence; prevented tuber production. Etiolated shoots persisted for 6 to 8 Etiolated shoots persisted for 6 to 8 weeksweeks

Majek and Neary 1991Majek and Neary 1991

• Clear film: readily punctured by nutsedges Clear film: readily punctured by nutsedges when PAR was limited; Purple nutsedge (78%) when PAR was limited; Purple nutsedge (78%) more effective in puncturing clear mulch than more effective in puncturing clear mulch than yellow nutsedge (43%) (Chase et al. 1998).yellow nutsedge (43%) (Chase et al. 1998).

• Clear plastic allows weeds to grow, foliage Clear plastic allows weeds to grow, foliage pushes up the mulch 10 to 20 cm. (Majek and pushes up the mulch 10 to 20 cm. (Majek and Neary 1991).Neary 1991).

Greenhouse Study: July 2001Greenhouse Study: July 2001

How about this mulch?How about this mulch?


A tale of two tubersA nutsedge is a nutsedge is a nutsedge?1 tuber then 10 tubers then 1000 tubersHow do I get rid of my nutsedges? Are all mulches created equal?

• Solarization: fact or fiction?Solarization: fact or fiction?

How deep are nutsedges How deep are nutsedges distributed in the soil profile?distributed in the soil profile?

Siriwardana and Nishimoto 1987Siriwardana and Nishimoto 1987 All within top 40 cm:Horowitz 1972All within top 40 cm:Horowitz 1972

Lethal Temperatures for NutsedgeLethal Temperatures for Nutsedge

• Holt and Orcutt (1996): Tuber Holt and Orcutt (1996): Tuber sprouting inhibited at constant sprouting inhibited at constant temperatures above 44 C (2 wks).temperatures above 44 C (2 wks).

• Chase et al. 1999: Objective was to Chase et al. 1999: Objective was to approximate actual field conditions. approximate actual field conditions. 45 C delayed nutsedge sprouting, 45 C delayed nutsedge sprouting, required 50 C for inhibition (2 wks). required 50 C for inhibition (2 wks). Used Cycling Temperatures: 6 Hr. Used Cycling Temperatures: 6 Hr. Hot and Cool to 26 C.Hot and Cool to 26 C.

70 C for 30 minutes: 70 C for 30 minutes: 50% reduction50% reduction




Preparation of Nutsedge Tubers for Heat TreatmentsPreparation of Nutsedge Tubers for Heat Treatments

Objective: Characterize Relation Among Heat treatments, Objective: Characterize Relation Among Heat treatments, Duration of Exposure, and Nutsedge Tuber ViabilityDuration of Exposure, and Nutsedge Tuber Viability

LDLD5050: : 50C = <15 minutes50C = <15 minutes

45C = 48 hours45C = 48 hours35C = >96 hours35C = >96 hours

• Yellow Nutsedge:Yellow Nutsedge:• 45 C for 8 hours = 45 C for 8 hours = >> 90% Tuber Viability 90% Tuber Viability• 5050+ + C for 15 minutes = C for 15 minutes = << 50% Tuber Viability 50% Tuber Viability

• Purple Nutsedge:Purple Nutsedge:• 50 C for 8 hours = > 70% Tuber Viability50 C for 8 hours = > 70% Tuber Viability• 55 C for 4 hours = 55 C for 4 hours = << 20% Tuber Viability 20% Tuber Viability• 60 C for 1 hour = < 5% Tuber Viability60 C for 1 hour = < 5% Tuber Viability

• How hot can we get our soils? How hot can we get our soils?

• How long can they stay this hot?How long can they stay this hot?

Preliminary ConclusionsPreliminary ConclusionsLethal Temperature/Duration of Exposure:Lethal Temperature/Duration of Exposure:

Questions, Comments, Concerns?Questions, Comments, Concerns?

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Nutsedge (Cyperus spp.) Biology: Implications For Management Dr. Theodore M. Webster Crop Protection...

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