Conyza bonariensis glyphosate resistant the need for a new approach
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Conyza bonariensis glyphosate-resistant: the need for a new approach. Miguel-Angel Sevillano, Juan Trigo, Gabriel Pardo, Jose-Maria Urbano. Huesca, September 6th, 2011. Introduction. Conyza bonariensis. Major weed problem in no-till permanent crops in Spain

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Conyza bonariensis glyphosate resistant the need for a new approach

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

Miguel-Angel Sevillano, Juan Trigo, Gabriel Pardo, Jose-Maria Urbano

Huesca, September 6th, 2011


Introduction

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.


Introduction1

Introduction

Conyza bonariensis

  • Over-reliance on glyphosate increases the problem.

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


Introduction2

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.


Introduction3

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.


Introduction4

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.


Introduction5

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.


Objectives

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.


Material and methods

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.


Material and methods1

Material and Methods

10 treatments:

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


Material and methods2

Material and Methods

  • Chlorophyll

  • Fitotoxicity

  • Mortality

  • Biomass

Data

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


Material and methods3

Material and Methods

Dates

*DDS: Days after sowing.

**DDT: Days after trasplanting.

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


Results

Results

  • Glyphosate

  • B & D pops: glyphosate resistant

Fitotoxicidad 28DDT

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


Results1

Results

  • Glyphosate

  • Resistant pops survive

Mortalidad 28DDT

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


Results

Fitotoxicidad 28DDT

Mortalidad 28DDT

Flazasulfuron

Lack of eficacy, when applied in postemergence.

There is diferential response, but not resistance.


Results

Mortalidad 28DDT

Glyphosate + flazasulfuron

Lack of eficacy against resistant pops


Results

Fitotoxicidad 28DDT

Mortalidad 28DDT

Testigo

MCPA & Fluroxypir

Similar results: relatively good eficacy

No diferential response

Mortality is low


Results

Mortalidad 28DDT

Fitotoxicidad 28DDT

Glyphosate + auxinics

Increased eficacy

Mortality is not 100%


Results

Fitotoxicidad 28DDT

Mortalidad 28DDT

Amitrol

Phytotoxic

Low mortality in problematic pops


Results

Fitotoxicidad 28DDT

Mortalidad 28DDT

Glyphosate + amitrol

Glyphosate + amitrol = amitrol

Low mortality

Not very interesting


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?



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