Agriculture: Apple Pest Management Guidelines

Most Effective Treatment Timings For Key Diseases

Note: Not all indicated timings may be necessary for disease control.

Disease Fall Delayed dormant Green tip Pink bud Petal Fall/ Cover Sprays
Scab1 ++2 ++2 +++ +++ +++
Powdery mildew3 +++ +++
Fire blight + ++ +++ +++4

Rating: +++ = most effective, ++ = moderately effective, + = least effective, and — = ineffective
1Protection of early tissue is important. Additional applications should be made according to infection periods as determined by the Mills table.
2 Disruption of pseudothecial (ascostroma) development (fall) and inactivation of overwintering twig lesions (delayed dormant); effects of these treatments on disease control is uncertain.
3 Early applications are most effective; additional applications are made if mildew continues.
4 Start management program at the beginning of bloom and continue through bloom including "rat-tail" bloom throughout spring. Several models are available for forecasting infection periods and treatment timing. Models include: Maryblyt, Cougar Blight, etc.

Acknowledgment: Adaskaveg et al., 2017. Efficacy and Timing of Fungicides, Bactericides, and Biologicals for Deciduous Tree Fruit, Nut, Strawberry, and Vine Crops (PDF).

Text Updated: 06/17