SDHI Fungicides
 
Membership

The SDHI Working Group is comprised of the following members:

Kristin Klappach (Chairwoman)
BASF
Martin Teichmann
BASF
Gerd Stammler
BASF
Martin Semar
BASF
Andreas Mehl
Bayer CropScience
Dominique Steiger
Bayer CropScience
Andreas Goertz
Bayer CropScience
Przemyslaw Szubstarski
Du Pont
Jean-Luc Genet
Du Pont
Bernard Straebler
Du Pont
Matthew Kane
LKC
Andy Leadbeater Syngenta
Helge Sierotzki Syngenta
Steve Dale Syngenta
Steve Parker
Chemtura
Introduction and General Information:

The FRAC SDHI Working Group is responsible for common resistance management recommendations for the SDHI fungicides (benodanil, bixafen, boscalid, carboxin, fenfuram, fluopyram, flutolanil, fluxapyroxad, furametpyr, isopyrazam, mepronil, oxycarboxin,penflufen, penthiopyrad, sedaxane and thifluzamid).

The above-mentioned fungicides are in general cross-resistant and have been grouped under the FRAC Code No. 7 in the revised FRAC Code List.

CODE TARGET SITE
OF ACTION
GROUP
NAME
CHEMICAL GROUP COMMON NAME COMMENTS
7 Complex II;
succinate-
dehydrogenase
  Phenyl-benzamides Benodanil
Flutolanil
Mepronil
Resistance
known for
several fungal
species in field
populations and
lab mutants.
Target site
mutations in sdh
gene, e.g. H/Y
(or H/L) at 257,
267, 272 or
P225L.

Medium-high risk.
Resistance
management
required
  Pyridinyl-ethyl-
benzamide
Fluopyram
  Furan-carboxamides Fenfuram
  Oxathiin-
carboxamides
Carboxin
Oxycarboxin
  Thiazole-
carboxamides
Thifluzamide
  Pyrazole-
carboxamides
Bixafen
Fluxapyroxad
Furametpyr
Isopyrazam
Penflufen
Penthiopyrad
Sedaxane
  Pyridine-
carboxamides
Boscalid

SDHI fungicides were discovered more than 40 years ago. Due to the limited disease and application spectrum of the “first generation” carboxamides, resistance under commercial conditions remained limited to a few diseases (basidiomycetes) and crops, e.g. Puccinia horiana, chrysanthemum rust, or Ustilago nuda, loose smut in barley.

In addition to these “first generation” molecules, the group of SDH inhibitors was meanwhile increased, with broad spectrum fungicides controlling a variety of diseases in various crops.

The target enzyme of SDH inhibitors is succinate dehydrogenase (SDH, so-called complex II in the mitochondrial respiration chain), which is a functional part of the tricarboxylic cycle and linked to the mitochondrial electron transport chain (Keon et al., 1991). SDH consists of four subunits (A, B, C and D) and the binding site of ubiquinone (and of SDHIs) is formed by the subunits B, C and D.

Baseline studies and monitoring programmes have been initiated and are ongoing. Several target site mutations have been detected both in lab generated mutants (Stammler et al, 2007) and field studies (FRAC).

The currently known facts on target site mutations are summarised in a separate document (Published and newer cases of SDHI resistance in fungi).

 
Detection of Resistance (other monitoring data sources, non-FRAC)

List of confirmed cases of field resistance to SDHI.

Crop Disease Geography Source, reference
Pistachio Alternaria
alternata
US,
California
Avenot HF, Michailides TJ (2007).
Resistance to boscalid in Alternaria
alternata
isolates from pistachio in
California.
Plant disease 91 (10), 1345-1350
Cucurbits Corynespora
cassiicola
Japan,
Ibaraki
Miyamoto T, Ishii H, Seko T, Tomita Y,
Kobori S & Ogawara T (2007).
Occurrence of boscalid-resistant
isolates of cucumber Corynespora leaf
spot fungus (C. cassiicola).
Japanese Journal of Phytopathology 74:
in press. (Japanese abstr.)
Cucurbits Podosphaera
xanthii
US, NY and
GA
M.T. McGrath (2008).
Fungicide sensitivity in Podosphaera
xanthii
and efficacy for cucurbit powdery
mildew in NY, USA, in 2003-2006.
Journal of Plant Pathology 90 (2,
Supplement), S 2.90

M. Miazzi and M.T. McGrath (2008).
Sensitivity of Podosphaera xanthii to
registered fungicides and experimentals
in GA and NY, USA, in 2007. Journal of
Plant Pathology (2008), 90 (2,
Supplement), S 2.90

A complete overview on resistant plant pathogenic organisms, including published cases of SDHI resistance,
can be viewed in the Publications area of the FRAC web site under (List of Resistant Plant Pathogens).

 
Monitoring Results and Use Recommendations
2013 Minutes of 2013 SDHI Meeting, Recommendations for 2014
2012 Minutes of 2012 SDHI Meeting, Recommendations for 2013
2011 Minutes of 2011 SDHI Meeting, Recommendations for 2012
 
Monitoring Methods
References

Keon JPR; White GA; Hargreaves JA (1991). Isolation, characterization and sequence of a gene conferring resistance to the systemic fungicide carboxin from the maize smut pathogen, Ustilago maydis. Current Genetics 19, 475-481

Stammler, G., Brix, H.-D., Glaettli, A., Semar, M., Schoefl, U. (2007). Biological properties of the carboxamide boscalid including recent studies on its mode of action. XVI International Plant Protection Congress 2007

 
 
Contact



Dr. Kristin Klappach

Chairwoman

BASF SE
Agricultural Research Station
Limburgerhof
D-67114 Limburgerhof, Germany
Tel: +49 62160- 27287
Fax: +49 62160- 6627287
Email: Dr. K. Klappach

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