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Nutsedge Biology: Implications For Management

AUTHOR
Dr. Theodore M. Webster
Crop Protection and Management Research Unit
USDA-ARS
Tifton, GA

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TABLE OF CONTENTS
  1. Nutsedge Biology: Implications For Management
  2. The Cyperaceae Family
  3. Nutsedges: Important Crops or Important Weeds?
  4. Nutsedges: Important Weeds
  5. Nutsedges: Distribution Map
  6. A Discussion of Nutsedges:
  7. Why are Nutsedges Such Persistent Weed Problems?
  8. Persistence: Tubers or Seeds?
  9. When Do Tubers Start to Form?
  10. Reproductive Success!
  11. From 1 Tuber, 700 Tubers Produced After 6 Months
  12. Competition for Light
  13. A Discussion of Nutsedges:
  14. Identification Characteristics: Color
  15. Identification Characteristics: Blade Shape
  16. Identification Characteristics: Seed
  17. Identification Characteristics: Tuber
  18. A Discussion of Nutsedges:
  19. Evaluate the Spatial Dynamics
  20. Yellow Nutsedge vs. Purple Nutsedge
  21. Density Comparison
  22. Yellow Nutsedge Patch Expansion
  23. Purple Nutsedge Patch Expansion
  24. Patch Comparison
  25. Preliminary Conclusions
  26. Take Home Message?
  27. A Discussion of Nutsedges:
  28. Can We Predict Nutsedge Emergence?
  29. Herbicides and Nutsedge Control
  30. Purple Nutsedge and Glyphosate
  31. Rain, Rain Go Away
  32. Quick Burn! Control?
  33. Take Home Message?
  34. Fumigants and Nutsedge Populations
  35. A Discussion of Nutsedges:
  36. Polyethylene Mulch
  37. Plastic: Black, Clear, and IRT
  38. Clear Plastic Drawbacks
  39. Greenhouse Study: July 2001
  40. How About This Mulch?
  41. A Discussion of Nutsedges:
  42. How Deep are Nutsedges Distributed in the Soil Profile?
  43. Lethal Temperatures for Nutsedge
  44. Propagule Viability vs Temperature
  45. Preparation of Nutsedge Tubers for Heat Treatments
  46. Tuber Viability vs Duration
  47. Preliminary Conclusions. Lethal Temperature/Duration of Exposure:
  48. Questions, Comments, Concerns?



SLIDE CONTENTS
  1. Nutsedge (Cyperus spp.) Biology: Implications For Management Dr. Theodore M. Webster Crop Protection and Management Research Unit USDA-ARS Tifton, GA
  2. The Cyperaceae Family Cyperaceae or the Sedges include 17 different genera Those species most commonly viewed as troublesome weeds are found in the Cyperus genus. Of the 45 Cyperus species in the Southeast U.S., 29 are perennials There are two primary perennial Cyperus spp. that cause economic losses.
  3. Nutsedges: Important Crops or Important Weeds? Purple nutsedge tubers were a staple in a late-Paleolithic (~16,000 B.C.) in Egypt. Egyptian tombs dating to the 15th Century B.C. have been found to have recipes for ground tiger nuts (aka nutsedge tubers) mixed with honey. Theophrastus (d. 287 B.C.): Egyptians boiled yellow nutsedge tubers in beer Negbi 1992
  4. Nutsedges: Important Weeds Purple nutsedge: identified as a weed growing in cropland areas in 1st Century A.D. Purple nutsedge is considered the World’s Worst Weed. Yellow nutsedge is one of the Top 5 World’s Worst Weeds. Negbi 1992 Holm et al. 1977
  5. Southern Weed Science Society Weed Guide Yellow Nutsedge (Cyperus esculentus L.) Cold tolerance: 95% of tubers survived 2 C for 12 weeks when buried at 10 cm Distributed in areas where soil freezes Purple Nutsedge (Cyperus rotundus L.) Cold Intolerance: <10% of tubers survived 2 C for 12 wks at 10 cm Distributed in areas where soil freezes infrequently Stoller 1973
  6. A Discussion of Nutsedges: A tale of two tubers: why are nutsedges 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?
  7. Why are nutsedges such persistent weed problems? Estimated half life of a Purple Nutsedge tuber is 16 months Predicted longevity of a tuber is 42 months Burial at 8 and 23 cm did not affect tuber dormancy/viability Neeser et al. 1997
  8. Persistence: Tubers or Seeds? Purple nutsedge samples showed very limited intraspecific variation (RAPD). Seeds were produced, but none germinated. Yellow nutsedge samples showed a wide range of variation. 17% of the flowers produced seed. Viable seed produced 2 wks after full bloom. 78% of the seed germinated. Field studies indicate only 0.78% of seed established into a plant. Okoli et al. 1997 Thullen and Keeley 1979 Lapham and Drennan 1990
  9. When Do Tubers Start to Form? Tuber initiation: 6 to 8 Weeks After Foliar Emergence (same time as flowering). Underground structures have more biomass than the aboveground foliage by 6 WAFE. Tuber chains formed by 10 WAFE. Long days stimulate: shoot, root, and rhizomes Short days stimulate: tuber and floral production. Hauser 1962 Williams 1982
  10. Reproductive Success! Purple nutsedge planted at 1-ft intervals (43,560 plants/acre) produced in 1 season: 3,090,000 plants/acre 4,442,000 tubers and bulbs/acre Cultivation in the second season did not affect the number of tubers and bulbs. Heavy shading (72% shade) during the second growing season reduced tuber and bulb formation. Hauser 1962
  11. Yellow Nutsedge Tubers: From 1 tuber 700 tubers produced after 6 Months of Growth
  12. Competition for Light Yellow nutsedge appears to be more tolerant of shade than Purple nutsedge Yellow nutsedge biomass in 30% shade was not different than in full sunlight. Purple nutsedge biomass was reduced in a linear with light. Yellow nutsedge has a lower light compensation point (84 µmol m-2 s-1) than purple nutsedge (127 µmol m-2 s-1). Santos et al. 1997 Jordan-Molero and Stoller 1978
  13. A Discussion of Nutsedges: A tale of two tubers A nutsedge is a nutsedge is a nutsedge? Or How can I distinguish these species? 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?
  14. YELLOW NUTSEDGE: - Yellow florets - Blades: lighter green PURPLE NUTSEDGE: - Dark red/purple florets - Blades: deeper green
  15. PURPLE NUTSEDGE blade has a short, abrupt tip YELLOW NUTSEDGE: blade has a long, drawn-out tip Three-Ranked Triangular-Shaped
  16. Taster’s Choice PURPLE NUTSEDGE YELLOW NUTSEDGE
  17. Purple Nutsedge: Tuber Chains Yellow Nutsedge: Tubers directly attached to mother plant
  18. A Discussion of Nutsedges: A tale of two tubers 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?
  19. YELLOW NUTSEDGE PURPLE NUTSEDGE Objective: Evaluate the Spatial Dynamics of Yellow and Purple Nutsedge Expansion After 3 and 6 Months (From a Single Planted Tuber)
  20. Yellow Nutsedge Purple Nutsedge
  22. Yellow Nutsedge Patch Expansion: 6 months of growth from a single tuber Each Tick = 12.7 cm Scale 0 to 0.5 m Each Tick = 12.7 cm Scale 0 to 0.5 m Patch Area: 0.18 m2 177 Yellow Nutsedge Shoots Max. Density: 7000 shoots/m2
  23. Purple Nutsedge Patch Expansion: 6 months of growth from a single tuber Each Tick = 12.7 cm Scale 0 to 2.0 m Each Tick = 12.7 cm Scale 0 to 4.2 m Patch Area: 7.85 m2 518 Purple Nutsedge Shoots Max. Density: 280 shoots/m2
  24. Each Tick = 12.7 cm Scale 0 to 2.0 m Each Tick = 12.7 cm Scale 0 to 4.2 m Each Tick = 12.7 cm Scale 0 to 4.2 m Each Tick = 12.7 cm Scale 0 to 2.0 m Yellow Nutsedge Purple Nutsedge 7.85 m2 0.18 m2
  25. Preliminary Conclusions Purple nutsedge produced: Similar number of shoots at 3 months 2-fold more shoots than did yellow nutsedge at 6 months Purple nutsedge expanded to a patch size 31-fold greater than yellow nutsedge Yellow Nutsedge does not distribute itself far from the mother tuber
  26. Take Home Message? Confirms the predictions of a spatial model of yellow nutsedge growth: farming operations are the main cause of yellow nutsedge dispersal in the field (Schippers et al. 1993). Purple nutsedge is well suited to distribute itself through its environment.
  27. A Discussion of Nutsedges: A tale of two tubers A nutsedge is a nutsedge is a nutsedge? 1 tuber then 10 tubers then 1000 tubers How do I get rid of my nutsedges? Herbicides and Fumigants Are all mulches created equal? Solarization: fact or fiction?
  28. Yellow Nutsedge: 80% Emergence by 6 May 1999 and 30 April 2000 Purple Nutsedge: 80% Emergence by 1 June 1999 and 21 May 2000 Can We Predict Nutsedge Emergence?
  29. Herbicides and Nutsedge Control Yellow Nutsedge Bentazon (75%) Metolachlor (55-75%) Glyphosate (55%) Halosulfuron (95%) Imazapic (80%) Imazethapyr (60%) Fomesafen PRE (85%) POST (60%) MSMA 1 lb ai/A (45%) 2 lb ai/A (90%) Purple Nutsedge Bentazon (20%) Metolachlor (<20%) Glyphosate (70%) Halosulfuron (95%) Imazapic (90%) Imazetheapyr (70%) Fomesafen PRE (35%) POST (?) MSMA 1 lb ai/A (30%) 2 lb ai/A (65%)
  30. Purple Nutsedge and Glyphosate Purple nutsedge control was not improved when glyphosate was tank mixed with: chlorimuron imazaquin pyrithiobac Rao and Reddy 1999 Glyphosate at 1.0 kg/ha required 72 hrs to translocate to the tuber. Glyphosate at 2.0 kg/ha required 36 hrs. Glyphosate kills foliage and tubers directly attached to treated plants.
  31. Rain, Rain Go Away Simulated rainfall at 1 and 24 hours reduced glyphosate efficacy on purple nutsedge 50 and 33%, respectively. A rain-free period of 72 hours was needed to avoid loss of glyphosate activity. Bariuan et al. 1999
  32. Quick Burn! Control? Paraquat will quickly dessicate foliage and stop new tuber production, however the effects are temporary as new shoots will emerge from the tuber (Pereira et al. 1987).
  33. Take Home Message? Which nutsedge do you have? Herbicide efficacy is often rate dependent; crop tolerance, weed efficacy, and economics dictate herbicide rate. There are no quick fixes with nutsedges - Management of nutsedge species is a multi-year process.
  34. Fumigants and Nutsedge Populations Methyl Bromide: 74 to 100% reduction in nutsedge numbers through plastic compared to UTC (1,3-dichloropropene + Chloropicrin + Metham Sodium) and (Methyl Iodide): Early: 76% and 91% Reduction Late: 22% and 21% Increase 1,3-dichloropropene + Chloropicrin: (Inconsistent results) 90%+ Reduction in 1998 12% Reduction and 120% Increase in 1999 Webster et al. 2001
  35. A Discussion of Nutsedges: A tale of two tubers 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?
  36. Nontreated Control: Polyethylene Mulch Nontreated Control: Bare Ground Nutsedge Crowfootgrass Polyethylene mulch suppresses weed growth, but creates a niche for nutsedges
  37. Black plastic: 11% of yellow nutsedge shoots punctured and emerged through; tubers were produced. Clear plastic: yellow nutsedge shoots did not puncture; caused yield reduction; tubers were produced. IRT plastic: suppressed yellow nutsedge emergence; prevented tuber production. Etiolated shoots persisted for 6 to 8 weeks Majek and Neary 1991
  38. Clear film: readily punctured by nutsedges when PAR was limited; Purple nutsedge (78%) more effective in puncturing clear mulch than yellow nutsedge (43%) (Chase et al. 1998). Clear plastic allows weeds to grow, foliage pushes up the mulch 10 to 20 cm. (Majek and Neary 1991).
  39. Greenhouse Study: July 2001
  40. How about this mulch?
  41. A Discussion of Nutsedges: A tale of two tubers 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?
  42. How deep are nutsedges distributed in the soil profile? Siriwardana and Nishimoto 1987 All within top 40 cm:Horowitz 1972
  43. Lethal Temperatures for Nutsedge Holt and Orcutt (1996): Tuber sprouting inhibited at constant temperatures above 44 C (2 wks). Chase et al. 1999: Objective was to approximate actual field conditions. 45 C delayed nutsedge sprouting, required 50 C for inhibition (2 wks). Used Cycling Temperatures: 6 Hr. Hot and Cool to 26 C.
  44. 70 C for 30 minutes: 50% reduction 60 C for 30 minutes: 20% reduction 90 C for 30 minutes: 100% reduction 80 C for 30 minutes: 80% reduction
  45. Preparation of Nutsedge Tubers for Heat Treatments Objective: Characterize Relation Among Heat treatments, Duration of Exposure, and Nutsedge Tuber Viability
  46. LD50: 50C = <15 minutes 45C = 48 hours 35C = >96 hours
  47. Yellow Nutsedge: 45 C for 8 hours = > 90% Tuber Viability 50+ C for 15 minutes = < 50% Tuber Viability Purple Nutsedge: 50 C for 8 hours = > 70% Tuber Viability 55 C for 4 hours = < 20% Tuber Viability 60 C for 1 hour = < 5% Tuber Viability How hot can we get our soils? How long can they stay this hot? Preliminary Conclusions Lethal Temperature/Duration of Exposure:
  48. Questions, Comments, Concerns? Twebster@tifton.cpes.peachnet.edu http://www.cpes.peachnet.edu/cpmru/Webster.HTM http://gaweed.com