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Bloom
Use the same materials as in the pink spray. Do not go over 5 days between half-sprays, and shorten this period in wet weather. Apply the bloom spray at a tractor speed 0.5 mph faster.
Apple scab. Peak release of primary apple scab spores (ascospores) usually occurs around bloom stage in Pennsylvania.
Powdery mildew. If powdery mildew is a problem, refer to Table 5-2 and Part II, Diseases, Pests, and Natural Enemies, for management recommendations.
Cedar apple rust. If cedar apple rust is historically a problem in an orchard, refer to Table 5-3 and Part II, Diseases, Pests, and Natural Enemies, for management recommendations.
Fire blight. Conditions favorable for infection include (1) open blossoms or succulent new growth, (2) an average daily temperature of 65°F or higher, plus (3) rainfall or a relative humidity of 60 percent or higher. Apply first streptomycin spray anytime after first blossoms open when above conditions exist or are expected within 24 hours. Repeat sprays at 5- to 7-day intervals through late bloom. A minimum of two applications is necessary to provide control.
Use streptomycin formulations at 4 to 8 ounces per 100 gallons dilute (60 to 100 ppm) or 1.5 pounds per acre concentrate (use at least 50 gal mixture/A), plus 1 pint Regulaid in each 100 gallons of spray. Streptomycin formulations are much more effective when applied during slow drying conditions such as at night. Refer to Part II: Diseases, Pests, and Natural Enemies, for more information on fire blight.
Gypsy moth. For gypsy moth control during bloom, refer to Bacillus thuringiensis (Bt) in Part III.
Obliquebanded leafroller. If obliqueband leafroller larvae are problematic, use a Bacillus thuringiensis (Bt) product listed in Part III.
Boron nutrition. Boron should be applied in an annual maintenance program. Each year apply a single spray of 1.0 pound of Solubor per 100 gallons (4 lb/acre) sometime during the period of full bloom through the first cover spray. In cases of documented deficiency, refer to Foliar Application of Nutrients in Part I.