Presented by: Bharati Singh

http://archives.eppo.org/MEETINGS/2010_conferences/septoria.htm

Outlines

• Introduction• Aim of workshop• Mode of action of azole• Conclusion and recommendation

Introduction

• Septoria leaf blotch (Mycosphaerella graminicola), foliar disease of wheat (EPPO countries)

• Resistance to different triazole and DMI (De methylation inhibitors)

• Significant complexity in the resistance mechanism to triazole

• Accounts 10-20% loss in yield and 40 percent in some case

• EPPO workshop on azole fungicides and septoria leaf blotch control was held on 2010-12-07/09 at Rothamsted Research (Harpenden, GB)

• Aim of the workshop: to bring together the latest scientific knowledge,agronomic practices and regulatory information

• 70 participants from 12 EPPO countries and 9 agrochemical companies.

• Workshop was divided into two working group

Purpose: build up the information and inputs into some general recommendations regarding the use of triazole for septoria control in the future

Mode of action of azole

Sterol ergesterol

Sterol Sterol 14α- demethylase

Sterol 14α- demethylase

Or CYP51

Sterol 14α- demethylase

Azole

Accumulation of 14α- methylsterols on fungal surface

Arrest of fungal growth

Conclusions and recommendations

Key agronomic issues:• Azole fungicides are major factor in the

management of the disease• Shifts in sensitivity and loss of efficacy of the

pathogen• Mutations in the CYP5I target gene are

important in the development of resistance to azole

Key messasge

• Provide clear message to farmers and advisors for the exchange of information across EPPO countries

• Label recommendations• Understanding of the need to apply resistance

management strategies• Non-chemical methods • Resistant cultivars

Research and information requirements

Workshop participants expressed a need:• Monitoring of field populations to determine

future shifts• Better understanding of the role of

alternation/mixture as anti- resistance strategies

• New insights into the s.tritici x wheat varietal interaction

Importance of azoles and shifts in sensitivity• Increase of genotypic,phenotypic diversity and shift in azole

sensitivity not affected all azoles to same extent• Different azoles select for different mutations at the target

site depending on the mutation, differential shifts • Anti-resistance strategies for the Succinate Dehydrogenase Inhibitor(SDHI) group of chemistry can not be managed

without azoles

• New strains of Septoria can be expected; identifying future azoles requirement is difficult

Maintaining all or a broad spectrum of azoles is important

Resistance strategies• Triazoles,a medium risk group,indicates for resistance

management strategies• Backbones of disease control in cereals,also vital to sustain

other chemistry• Where possible,different modes of action should be

employed• Should be no arbitrary restriction on the maximum number

of applications of azoles• Diversity of azoles should be incorporated as part of a

spray programme

Preventive or curative treatments

• Frequent preventive treatments are not economic• Multiple, low dose, preventive treatments:

undesirable• Extend the exposure period of pathogens• Eradicative treatments are generally considered to increase the risk of resistance development

Alternation or mixtures• Mixtures are a practical resistance management

strategy• It also delay the resistance emergence phase of

other disease• Multiple applications of same individual azole alone

may be undesirable

Dissemination of resistance strategies• Farmers need guidance regarding the complexity

of resistance situation• Should be communicated in a simple but reliable

and trustworthy way

Workshop participants noted that many journalist/ policymakers/funders employ dramatic statements

THANK YOU