Apple, Effectiveness of Several Pesticides at 6X Concentration Applied to Alternate Middles in Controlling Apple Pests, 1980

Each pesticide, or pesticide combination, was applied to two rows of 6 year old apple trees on as close to a weekly schedule as possible. Application was with a Swanson air blast sprayer calibrated to deliver 25 gpa (233.55 liters/ha) from each side, at 2 mph (3.22km/hr) and 100 pst (7.02kg/cm2) pump pressure. Sides of the trees sprayed were alternated on each successive spray date after bloom (May 22 and thereafter). Each treatment and the control contained four trees (16 total) of each of the cultivars Triple Red Delicious, Yellow Delicious, Commander Red York and Double Red Stayman. All plots were sprayed (one side only) on Apr 8, 25, May 12, 22, 28, Jun 4, II, 18, 25, Jul 2, 9, 16, 24, 30, Aug 6, 13. Fruit yield was much reduced by two severe frosts of 26°F (-3.34°C) and 24°F (-4.45°C) during bloom. This reduced the reliability of fruit injury data since the same fruit was counted on successive sample dates out of necessity. Effectiveness of the materials was evaluated against several pests as follows: fruit damage was evaluated by counting injuries per 50 apples (where possible) on each of four trees of each of four cultivars. For analysis data from each cultivar were combined. Terminal injury by apple aphids was recorded as number infested out of ten terminals per tree for 16 trees per treatment (four trees of each of four cultivars). Mites and mite eggs were sampled by collecting 20 leaves per tree from each of 4 trees of each of 4 cultivars, brushed onto glass plates and counted with a binocular microscope following the Henderson-McBurnie method. Data were recorded as mites or mite eggs per leaf.