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Effects of long term irrigation with reclaimed wastewater on the efficacy and fate of ALS inhibiting herbicides

Effects of long term irrigation with reclaimed wastewater on the efficacy and fate of ALS inhibiting herbicides. Gal Dvorkin, M Manor, M Sibony, B Chefetz and B Rubin The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University in Jerusalem, Rehovot, Israel .

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Effects of long term irrigation with reclaimed wastewater on the efficacy and fate of ALS inhibiting herbicides

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  1. Effects of long term irrigation with reclaimed wastewater on the efficacy and fate of ALS inhibiting herbicides Gal Dvorkin, M Manor, M Sibony, B Chefetz and B Rubin The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University in Jerusalem, Rehovot, Israel

  2. Na’an- double cropping irrigated with pivot - 2.8.2006 The field is irrigated with reclaimed wastewater (RWW) for the last 40 years introduction

  3. Applied herbicides at Na’ad cotton field 2006 • 28.4.06 – Glyphosate 0.84 kg ae/ha • 30.4.06 – Prometryn 1.5 kg/ha • 21.5.06– Trifloxysulfuron 11.25 g/ha • 11.6.06 – Fluometuron 1.25 kg/ha • 26.6.06 – Prometryn 1.4 kg/ha • 14.7.06 – Trifloxysulfuron 11.25 g/ha introduction

  4. The main problems in Na’an field • The trifloxysulfuron that was applied twice in the highest recommended dose, was not able to control the Amaranthus palmeri. • Wheat that followed the cotton 4 months after the trifloxysulfuron application, was not damaged by residues that were supposed to remain in the soil. introduction

  5. Hypothesis • The long term irrigation with RWW have caused changes in the soil (OM and microorganisms), thus decreasing the persistence of ALS herbicides. • The Amaranthus palmeri populationdeveloped resistance to trifloxysulfuron hypothesis

  6. Research Objective • To elucidate the effect of a long term irrigation with RWW on the behavior of ALS inhibiting herbicide trifloxysulfuron in the soil

  7. Materials and Methods • Field experiments were conducted at the problematic field, in 2007,2008 and 2009. • Dose response curves to trifloxysulfuron in RWW irrigated soil and in fresh water (FW) irrigated soil • Develop chemical analysis method to extract and estimate trifloxysulfuron residues from the soil.

  8. The field experiments • Herbicides were sprayed with a “backpack sprayer”, each plot 2 m wide and 12 m long • Every 2 weeks soil samples were taken using soil driller • Herbicide content in the soil samples was examined using Sorghum bicolor as test plant, and harvested 3 weeks later. Materials and methods

  9. Results of field experiments

  10. Results field experiment 2008 Pelmer amaranth on the day of post-em application -16.6.08 Results

  11. Trifloxysulfuron 11.25 g ha-1 -15.7.08 Results

  12. 150 mm 14 day Trifloxy 11.25 Control 460 mm 54 40 178 mm Control Trifloxy 11.25 Control Trifloxy 11.25 27 Bioassay of soil samples 70 mm 0 Trifloxy 11.25 Control Control Trifloxy 11.25 Results

  13. A A A A A AB B Results bioassay 0-15 cm depth Results

  14. Lab experiments

  15. Comparing the effect of trifloxysulfuron in RWW soil and FW irrigated soil • RWW irrigated soil was collected from Na’an field, and FW irrigated soil was collected from near by field. • Both soils were air dried, sieved (5 mm), and were put in 7*7*7 (cm) plastic pots. • The pots were planted with wheat, and sprayed with trifloxysulfuron and irrigated with FW. • After 3 weeks in the screen house, Plant harvested and shoot fresh wt was recorded Materials and methods

  16. Soil properties

  17. Results RWW soil- Trifloxysulfuron control 1.9 g ai/ha 3.8 g ai/ha 30 g ai/ha 7.5 g ai/ha 15 g ai/ha FW soil- Trifloxysulfuron 1.9 g ai/ha 3.8 g ai/ha 30 g ai/ha 7.5 g ai/ha 15 g ai/ha control

  18. Results

  19. RWW soil-trifloxysulfuron 30 g ai/ha 1.9 g ai/ha 3.8 g ai/ha 7.5 g ai/ha 15 g ai/ha control Fresh water soil- trifloxysulfuron Results

  20. Results

  21. Chemical analysis of Trifloxysulfuron in the soil • Soil samples were collected from the field experiment in Na’an. • The samples were extracted and filtered. • Extracts were injected to LC/MS and a method for identifying trifloxysulfuron residues in the soil was developed.

  22. Preliminary results Results

  23. Conclusions • Trifloxysulfuron dissipates faster in RWW soil compare to FW soil. • Enhanced dissipation of trifloxysulfuron under field conditions is evident. • More experiments are required in order to determine the factors involved in the faster dissipation of trifloxysulfuron in the soil

  24. Acknowledgments • Prof. Tom Mueller, University of Tennessee. • Weed lab group: Coby Goldwasser, Hadas Rozenberg, Or Levy, Maor Mazraffi, Ella Cohen Alon Vallch and Tal Naamat. • Soil & Water lab- Michal Shechter, Ziva Hochman, Daniela Harush, Yaniv Olshansky and Shay Eldad.

  25. Thank you very much for listening

  26. Questions?

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