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First Cover
Blister spot on Crispin (Mutsu). Crispin apples are highly susceptible to the blister spot bacterial infections about 2 weeks after petal fall for a period of 2-4 weeks. The causal bacteria overwinter in the infected buds and multiply on the leaf surface in spring. Rain washes the bacteria onto the fruit where they infect through the lenticels to cause the reddish spot. A brief shower is all that is required to distribute the bacteria to new infection sites. The standard recommendation for control of this disease is to apply streptomycin at 1/2 pound per 100-gallon-dilute rate 10 to 14 days after petal fall. If the weather pattern of rain continues, two additional sprays should be applied at weekly intervals. Resistance of the bacteria to streptomycin has been documented in commercial orchards in the northeastern United States. Do not use more than necessary or up to three applications.
Fire blight. Do not use streptomycin on apple trees within 50 days of harvest.
Codling moth. If present, codling moth can be controlled with various products, including either the broad-spectrum insecticides (e.g., Avaunt, azinphos-methyl, Imidan) applied at 250 and 550 degree days after biofix, or the more selective insecticides and virus products, including Assail, Calypso, Intrepid, Rimon, and Cyd-X. In orchards with suspected organophosphate resistance, a high rate of Assail (3.4 ounces), Calypso (4.0-8.0 fluid ounces), Intrepid (16 fluid ounces), or Rimon (20-30 fluid ounces) should be used. Rimon should be applied at 75-100 degree days following biofix and again 14-17 days later. Intrepid should be applied at 150 and 450 degree days after biofix. Applications of Cyd-X (2-6 ounces per acre) should commence at 250 degree days and repeated every 7-9 days during the first brood egg hatch period.
Cork and bitter pit in fruit. See Part I.
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, refer to Table 5-3 and Part II: Diseases, Pests, and Natural Enemies, for management recommendations.