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(A46) APPLE: Malus domestica Borkhausen, 'Idared', 'Empire', 'Cortland', 'McIntosh' COMPARISON OF INSECTICIDES AGAINST OBLIQUEBANDED LEAFROLLER ON APPLE, H. Reissig, D. Combs, and C. Smith Department of Entomology NYS Agriculture Experiment Station Geneva, NY 14456 Phone: (315)-787-2336 Obliquebanded leafroller (OBLR): Choristoneura rosaceana (Harris) Treatments for comparison of insecticides were applied with a Durand-Wayland Silverliner 300 air-blast sprayer calibrated to deliver 100 gpa to plots of apple trees in two orchards: (1) Lagoner's Orchard-'Empire' trees, which were 9 ft high and planted 7.5 by 18 ft apart, and 'Cortland' trees, which were 7 ft high and planted 8 by 18 ft apart; and (2) Orbaker Orchard-'McIntosh' trees, which were 9 ft tall and planted 10 by 18 ft apart, and 'Idared' trees, which were 9 ft tall and planted 6 by 20 ft apart. Plots were rectangles (» 0.1 acres) of three adjacent rows with either 5 or 10 trees in each row. Treatment blocks along with untreated check plots were arranged in an RCB design and replicated twice in each orchard (one replication set up in each cultivar of apples). Summer populations of larvae were compared in different plots by examining 20- 100 growing terminals from two trees in the middle of the center row of each plot for live larvae on 30 Jul after the majority of egg masses had hatched. Harvest evaluations were conducted on 7-12 Sep by randomly selecting 200 apples from the center two trees in each replication and inspecting them for damage based on the USDA rating system. The initial levels of infestation in terminals from the summer generation of OBLR (20.0 and 50.0% infested terminals, respectively, in the Lagoner and Orbaker untreated check plots) were considerably higher in both research orchards than those observed in the previous season. However, as commonly observed in previous studies, levels of fruit damage in the research orchard were not highly correlated with infestations of the summer generation of larvae in terminals, since 30.0 and 7.8% of the fruit was damaged in untreated check plots as found at harvest, respectively, in the Lagoner and Orbaker orchards. The average fruit damage levels were generally higher among all the treatments at the Lagoner site than in those at the Orbaker site. Only three of the treatments applied in the Lagoner orchard, SpinTor, Proclaim, and the combination of Avaunt and Intrepid, significantly reduced fruit damage below that observed in the untreated check plots. Apple cultivar and tree canopy size may also have affected the efficacy of the treatments in the different orchards, since the Empire and Cortland trees in the Lagoner block were larger and had denser canopies than the McIntosh and Idared trees on the Orbaker farm. All treatments of Avaunt alone did not give adequate control, and damage was similar to that in the untreated check plots when data from the two orchards were combined. However, when the material was used in a mixture with the other chemicals, efficacy was improved, and the most effective chemical in these mixtures was Intrepid. As previously observed, Intrepid provided slightly better control of OBLR fruit damage than Confirm, particularly in the Lagoner orchard, in which OBLR pressure was higher. SpinTor was slightly more effective than Confirm or Intrepid in protecting fruit in the Lagoner Orchard. Fruit damage in the plots treated with the synthetic pyrethroids Asana and Warrior was very similar to that in the check plots in the Lagoner orchard, which indicates that the OBLR populations in this orchard were uniformly resistant to all of these materials. In contrast, the pyrethroids were as effective as the better standard and experimental materials in the Orbaker orchard and significantly reduced fruit damage below that in the check plots. The current materials tested that are considered standards, Confirm, SpinTor, and Lannate, all reduced fruit damage below that in the untreated checks, although SpinTor was the only material that gave a significant reduction in both test orchards. SpinTor provided the best overall performance in the trial, reducing fruit damage to < 7% when the data from both orchards was combined. This indicates that growers are already using the most efficient tool for OBLR control. Proclaim also gave good control when the orchards were combined. Although this product is not yet registered, it may provide a material available for future consideration. Manufacturers suggest that this product be applied with oil as an adjuvant, but because one of the growers used Captan in the test orchard, Latron B-1956 was substituted with apparently no loss of efficacy.
Arthropod Management Tests – Oxford University Press
Published: Jan 1, 2002
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