Powdery Mildew (Pears)

General Description

White powdery fungus growth on terminal shoots of pears is less evident than in apples. However pears are susceptible to fruit infection, which appears as black marks and russeting on young fruit (Fig. 1). Powdery mildew does not overwinter in pear buds, as it does on apple. Primary inoculum affecting pears originates from nearby apple orchards.








Figure 1. Pear fruit damaged by powdery mildew. (AAFC)


Cultural Control

Avoid planting Anjou pears near susceptible apple cultivars. Bartlett and Flemish Beauty are more resistant to powdery mildew.

Chemical Control

Fruit - Apply a fungicide registered for powdery mildew on pear at the pink stage to protect fruit from russeting. Additional sprays may be necessary under high disease pressure. 


  • Lime sulphur may cause fruit russet and disrupts integrated mite control. To minimize the risk of fruit damage, do not use past full bloom.
  • Sovran may severely injure certain varieties of cherries. Do not allow drift onto cherries.
  • Senator may harm predatory mites. If several sprays are applied, follow mite counts closely for indications of spray interference with predatory mite population. 

Updated July, 2018