Powdery Mildew (Peaches and Nectarines)

General Description

Powdery mildew, caused by the fungus Sphaerotheca pannosa, appears in late spring or early summer as white mildew spots on the fruit (Fig. 1) and foliage. Later the spots on the fruit turn a tan colour. When severe, it may crack the fruit.

 

 

 

 

 

 

Figure 1. Nectarine infected with powdery mildew fungus. 

Management

Cultural Control

  • Provide good air circulation through trees.

  • Cling peaches, nectarines and seedling peaches are especially susceptible and can serve as a source of infection.

  • Wild and cultivated roses can be a source of infection for powdery mildew on peaches and nectarines. They are affected by the same species of powdery mildew.

  • In some areas apple powdery mildew (Podosphaera leucotricha) can also cause injury to peach and nectarine fruit.  This appears as rusty spots. Avoid locating peach or nectarine blocks next to highly susceptible apple varieties. 

Chemical Control

A fungicide applied at husk fall and during early fruit development will prevent powdery mildew damage to most peach and nectarine fruit.  On very susceptible varieties provide coverage from full bloom to pit hardening. 

Fungicides registered for control or suppression of powdery mildew on peach include:

Updated July, 2018

Funding for this project was provided in part by Agriculture and Agri-Food Canada and the B.C. Ministry of Agriculture through programs delivered by the Investment Agriculture Foundation of B.C.

Agriculture and Agri-Food Canada, the B.C. Ministry of Agriculture and the Investment Agriculture Foundation of BC, are pleased to participate in the delivery of this project. We are committed to working with our industry partners to address issues of importance to the agriculture and agri-food industry in British Columbia. Opinions expressed in this publication are those of the BCFGA and not necessarily those of the Investment Agriculture Foundation, the B.C. Ministry of Agriculture or Agriculture and Agri-Food Canada.

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