Conyza bonariensis glyphosate-resistant: the need for a new approach.

1. Conyza bonariensis glyphosate-resistant: the need for a new approach. Miguel-Angel Sevillano, Juan Trigo, Gabriel Pardo, Jose-Maria Urbano Huesca, September 6th, 2011

2. Introduction Conyza bonariensis • Major weed problem in no-till permanent crops in Spain • Adapted to develop herbicide resistance: • Worldwide (B, C1, D, G) • In Spain (C1 (1987), G (2004)) Conyza bonariensis glyphosate-resistant: the need for a new approach.

3. Introduction Conyza bonariensis • Over-reliance on glyphosate increases the problem. Conyza bonariensis glyphosate-resistant: the need for a new approach.

4. Introduction Conyza bonariensis • Farmers want to have bare soil • At least in the line of trees • With glyphosate mixtures • Which mixtures? Conyza bonariensis glyphosate-resistant: the need for a new approach.

5. Introduction MOA that have been proposed to control C. bonariensis • Flazasulfuron (B) • Terbutilazine (C1) • Amitrol (F3) • Glyphosate (G) • Glufosinate (H) • Fluroxipyr (O) • MCPA (O) Conyza bonariensis glyphosate-resistant: the need for a new approach.

6. Localidad 19 (resistente). T4: Glyphosate (1080 g/ha) + Flazasulfuron (50 g/ha) T2: Glyphosate (1080 g/ha) Introduction Since 2004, glyphosate + flazasulfuron is recommended Conyza bonariensis glyphosate-resistant: the need for a new approach.

7. Introduction In 2009, control failures are reported in Ecija (Sevilla), after glyphosate + flazasulfuron, in olive farms. Conyza bonariensis glyphosate-resistant: the need for a new approach.

8. Objectives Confirm glyphosate resistance in Ecija pops Check for flazasulfuron resistance in Ecija pops Evaluate the eficacy of: - Amitrol (F3) - MCPA (O) - Fluroxipyr (O) Conyza bonariensis glyphosate-resistant: the need for a new approach.

9. Material and Methods 5 C. bonariensis pops. - A: susceptible check (2004) - B, C, D: Ecija’s pops (2009) - E: glyphosate resistant check (2004) 5 pops x 10 treatments x 6 reps x 2 (twice) Conyza bonariensis glyphosate-resistant: the need for a new approach.

10. Material and Methods 10 treatments: Conyza bonariensis glyphosate-resistant: the need for a new approach.

11. Material and Methods • Chlorophyll • Fitotoxicity • Mortality • Biomass Data Conyza bonariensis glyphosate-resistant: the need for a new approach.

12. Material and Methods Dates *DDS: Days after sowing. **DDT: Days after trasplanting. Conyza bonariensis glyphosate-resistant: the need for a new approach.

13. Results • Glyphosate • B & D pops: glyphosate resistant Fitotoxicidad 28DDT Conyza bonariensis glyphosate-resistant: the need for a new approach.

14. Results • Glyphosate • Resistant pops survive Mortalidad 28DDT Conyza bonariensis glyphosate-resistant: the need for a new approach.

15. Results Fitotoxicidad 28DDT Mortalidad 28DDT Flazasulfuron Lack of eficacy, when applied in postemergence. There is diferential response, but not resistance.

16. Results Mortalidad 28DDT Glyphosate + flazasulfuron Lack of eficacy against resistant pops

17. Results Fitotoxicidad 28DDT Mortalidad 28DDT Testigo MCPA & Fluroxypir Similar results: relatively good eficacy No diferential response Mortality is low

18. Results Mortalidad 28DDT Fitotoxicidad 28DDT Glyphosate + auxinics Increased eficacy Mortality is not 100%

19. Results Fitotoxicidad 28DDT Mortalidad 28DDT Amitrol Phytotoxic Low mortality in problematic pops

20. Results Fitotoxicidad 28DDT Mortalidad 28DDT Glyphosate + amitrol Glyphosate + amitrol = amitrol Low mortality Not very interesting

21. Conclusions • Estrategy A: - Increase herbicide rates - Add other products to the mixture • Estrategy B: - Are we optimizing the moment ? - Are we optimizing cultural practices (cover crops) ? - Have we explored all posibilities of non-chemical control (mechanical, physical, biological) ? - Can we predict the emergence ? None of the treatments achieved 100% control What should we do know?

22. Thanks for your attention