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

2. 2 Introduction Conyza bonariensis glyphosate-resistant: the need for a new approach. 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))

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

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

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

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

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

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

9. 9 Material and Methods Conyza bonariensis glyphosate-resistant: the need for a new approach. 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)

10. 10 Material and Methods Conyza bonariensis glyphosate-resistant: the need for a new approach. 10 treatments: TreatmentActive ingredientRate (kg ai/ha) 1Check- 2Glyphosate1,08 3Flazasulfuron0,0375 4Glyphosate + Flazasulfuron1,08 + 0,0375 5Amitrol3 6Glyphosate + Amitrol1,08 + 3 7Fluroxipir0,3 8Glyphosate + Fluroxipir1,08 + 0,3 9MCPA1,08 10Glyphosate + MCPA1,08 + 1,08

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

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

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

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

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

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

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

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

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

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

21. 21 None of the treatments achieved 100% control What should we do know? 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 ?

22. 22 Thanks for your attention