Apple, Comparison of Schedules Against OBLR, 1994

Abstract

Abstract Treatments were applied with a truck-mounted airblast sprayer to 0.25 acre plots of apple trees in two orchards. In the LaMont orchard the ‘Tdared’ trees were ca. 12 years old, 12 ft high, and planted 12 by 30 ft apart. In the Brown orchard the ‘Tdared’ trees were ca. 13 ft high and planted 15 by 18 ft apart. Treatments were arranged in a RCB design and replicated twice in each orchard. Two control schedules were compared: An early schedule in which the first spray was applied at the estimated first egg hatch, followed by two more protective sprays, and a standard schedule in which the first spray was applied at 640 DD (base temperature = 50°F) after the first male flight followed by a second protective spray. Sprays were applied in 100 gpa of water except for the last sprays in the LaMont orchard, which were applied in 200 gpa of water. Summer populations of larvae were compared by examining 20-50 growing terminals from each of five randomly selected trees per plot for live larvae on 12-14 Jul and 2 Aug. Fruit damage from the first summer generation of larvae was estimated on 19-22 Aug by sampling 100-150 apples from each of 5 randomly selected trees per plot. Apples were also examined at harvest and classified in USDA grades of Fancy, #1, and culls to evaluate the severity of damage.