Summary of main apple diseases and fungicide resistance

The current incidence of fungicide resistance in apple diseases is summarised in the following table.

Fungal disease Resistance identified Fungicides where identified and resistance type

(incidence)
Apple scab Yes dodine                                  resistant/sensitive (L)

carbendazim            }           resistant/sensitive (WS)

thiophanate-methyl  }

pyrimethanil                        reduced sensitivity (L)

kresoxim-methyl (QoI)       resistant / sensitive (not UK)
DMI (triazole)                     reduced sensitivity (L)
Apple powdery mildew Yes? DMI (triazole)                    reduced sensitivity                                                   .                                         (localised)
Blossom wilt (Monilinia laxa f.sp. mali) None  
Nectria canker None  
Crown rot/collar rot (Phytophthora cactorum) None  
Silver leaf None  
Sooty blotch None  
Fly speck None  
Gloeosporium rot Yes carbendazim           }            resistant/sensitive (WS)

thiophanate-methyl }
Penicillium rot Yes carbendazim           }            resistant/sensitive (WS)

thiophanate-methyl }
Botrytis rot Yes carbendazim           }            resistant/sensitive (WS)

thiophanate-methyl }

iprodione                              resistant/sensitive (rare)
Phytophthora rot Yes? metalaxyl                              reduced sensitive (rare)
  None  
  None  
  None  
  None?  

Key WS = widespread, L = low incidence