title: Evaluation of a matrix to calculate fungicide resistance risk.
abstract: BACKGROUND
  In the European Union, assessments of resistance risk are required by the regulatory authorities for each fungicide product and are used to guide the extent of anti-resistance strategies. This paper reports an evaluation of a widely used 'risk matrix', to determine its predictive value. Sixty-seven unique cases of fungicide resistance in Europe were identified for testing the risk assessment scheme, where each case was the first occurrence of resistance in a pathogen species against a fungicide group.
  
  
  RESULTS
  In most cases, high-, moderate- and low-risk categories for fungicide, pathogen and agronomic systems were each associated with significant differences in the number of years from fungicide introduction to the first detection of resistance (FDR time). The combined risk, calculated by multiplying the individual risk factors using the risk matrix, had useful predictive power (72.8% of FDR time variance accounted for; VAF) for all fungicides, but only limited predictive power (25.8% VAF) for single-site acting fungicides (the predominant type).
  
  
  CONCLUSIONS
  The resistance risk matrix has significant, but limited, predictive value. New fungicide modes of action, or pathogens that have become newly prevalent, cannot be assigned to risk categories until new methods of resistance risk assessment are developed.
authors.affiliation: ADAS Boxworth, Cambridge, UK.
authors.forename: Michael K
authors.initials: MK
authors.lastname: Grimmer
authors.forename: Frank
authors.initials: F
authors.lastname: van den Bosch
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Powers
authors.forename: Neil D
authors.initials: ND
authors.lastname: Paveley
mesh_terms: D018556:Crops, Agricultural; D025141:Drug Resistance, Fungal; D005062:European Union; D005658:Fungi; D005659:Fungicides, Industrial / Q000494:pharmacology*; D010935:Plant Diseases / Q000382:microbiology; D018570:Risk Assessment / Q000379:methods
chemical_list: D005659:Fungicides, Industrial
keywords: fungicide resistance; insensitivity; pathogen evolution; risk assessment