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Nutsedge ( Cyperus spp.) Biology: Implications For Management

Nutsedge ( Cyperus spp.) Biology: Implications For Management. Dr. Theodore M. Webster Crop Protection and Management Research Unit USDA-ARS Tifton, GA. The Cyperaceae Family. Cyperaceae or the Sedges include 17 different genera

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Nutsedge ( Cyperus spp.) Biology: Implications For Management

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  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. 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 Southern Weed Science Society Weed Guide 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 Lapham and Drennan 1990 Thullen and Keeley 1979

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

  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. YELLOW NUTSEDGE: blade has a long, drawn-out tip PURPLE NUTSEDGE blade has a short, abrupt tip Three-Ranked Triangular-Shaped

  16. YELLOW NUTSEDGE PURPLE NUTSEDGE Taster’s Choice

  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. PURPLE NUTSEDGE YELLOW 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

  21. Yellow Nutsedge Patch Expansion: 6 months of growth from a single tuber 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 Each Tick = 12.7 cm Scale 0 to 0.5 m

  22. Purple Nutsedge Patch Expansion: 6 months of growth from a single tuber 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 Each Tick = 12.7 cm Scale 0 to 2.0 m

  23. 0.18 m2 7.85 m2 Each Tick = 12.7 cm Scale 0 to 4.2 m Each Tick = 12.7 cm Scale 0 to 4.2 m Yellow Nutsedge Purple Nutsedge Each Tick = 12.7 cm Scale 0 to 2.0 m Each Tick = 12.7 cm Scale 0 to 2.0 m

  24. 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

  25. 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.

  26. 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?

  27. Can We Predict Nutsedge Emergence? Yellow Nutsedge: 80% Emergence by 6 May 1999 and 30 April 2000 Purple Nutsedge: 80% Emergence by 1 June 1999 and 21 May 2000

  28. 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%) Herbicides and Nutsedge Control

  29. Purple nutsedge control was not improved when glyphosate was tank mixed with: chlorimuron imazaquin pyrithiobac 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. Purple Nutsedge and Glyphosate Rao and Reddy 1999

  30. 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

  31. 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).

  32. 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.

  33. 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

  34. 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?

  35. Nutsedge Crowfootgrass Polyethylene mulch suppresses weed growth, but creates a niche for nutsedges Nontreated Control: Polyethylene Mulch Nontreated Control: Bare Ground

  36. 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

  37. 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).

  38. Greenhouse Study: July 2001

  39. How about this mulch?

  40. 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?

  41. How deep are nutsedges distributed in the soil profile? Siriwardana and Nishimoto 1987 All within top 40 cm:Horowitz 1972

  42. 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.

  43. 60 C for 30 minutes: 20% reduction 80 C for 30 minutes: 80% reduction 70 C for 30 minutes: 50% reduction 90 C for 30 minutes: 100% reduction

  44. Objective: Characterize Relation Among Heat treatments, Duration of Exposure, and Nutsedge Tuber Viability Preparation of Nutsedge Tubers for Heat Treatments

  45. LD50: 50C = <15 minutes 45C = 48 hours 35C = >96 hours

  46. Preliminary ConclusionsLethal Temperature/Duration of Exposure: • 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?

  47. Questions, Comments, Concerns? Twebster@tifton.cpes.peachnet.edu http://www.cpes.peachnet.edu/cpmru/Webster.HTM http://gaweed.com

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