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/White bud Pink bud/Full bloom Petal Fall/ Cover Sprays
Fire blight               0               1               2               3               34
Powdery mildew3               0               0               1               3               3
Scab1               22               22               3               3               3
Rating: 3 = most effective, 2 = moderately effective, 1 = least effective, and 0 = ineffective
1 Protection 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., 2022. Fungicides, Bactericides, Biocontrols, and Natural Products for Deciduous Tree Fruit and Nut, Citrus, Strawberry, and Vine Crops in California. (PDF)

Text Updated: 03/22
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