Apple, Summer Control of Obliquebanded Leafroller, 1991

Treatments were applied to single-tree plots of apple trees in two orchards in Wayne Co. NY: (1) 'Spyjohn' trees in the,Dathyn orchard were ca 15 years old, 4.8 m high, and planted at a spacing of 5.8 by 6.4 m apart. (2) 'Wayne' apples in the Mills Orchard were ca 20 years old, 5.2 m high, and planted at a spacing of 10.7 by 11.9m apart. Treatments were arranged in a randomized block design and replicated on 4 trees. All sprays were applied dilute to runoff (3,656 1/ha) at a pressure of 32 kg/cm2. Summer infestations of larvae were compared by examining up to 50 actively growing terminals (Mills Orchard) or 100 fruit clusters (Dathyn Orchard) for live larvae after the first spray of the early treatments (20 Jun) or after the last treatment (10 Jul) was applied. Fruit damage was estimated by sampling between 100 and 300 fruit/ tree around the periphery from the ground to eye level on 12-14 Aug, and again on 9-11 Sep. The following pest phenology parameters after the first catch of males in pheromone traps (3 Jun) were used to time sprays: 19-20 Jun to coincide with predicted first hatch of eggs; 27-28 Jun (620-628 degree days, base temperature = 43°F) to coincide with a cumulative egg hatch of approximately 40%; and 9-10 Jul, in accordance with standard practices to retreat at 10-14 day intervals to maintain continuous effective residues while larvae are active.