Whole-farm infestation trends and management programs for obliquebanded leafroller in apples


Abstract: Because of an incomplete understanding of the role of habitat, alternate hosts, and adult movement in NY fruit infestations by obliquebanded leafroller (OBLR), we wished to obtain a temporal and spatial picture of summer larval re-infestation patterns. In 2007, an unrealistically aggressive early season spray program was used to eradicate overwintered larvae on 3 commercial farms (17–32 acres) with a history of OBLR injury. Summer generation adults were monitored using a network of pheromone traps located at different orchard strata on all 4 ordinal sides. Weekly terminal and fruit samples were taken at each station. Although large numbers of adults were caught, larval terminal infestations and fruit damage remained low in all blocks. There were no substantial differences in adult catches, larval infestations or fruit damage in the different orchard strata. This suggested the utility of developing a sampling plan for the summer OBLR generation based on fruit damage rather than the traditional sampling of larvae on growing terminals. In 2008, methods above were repeated on 6 farms (20–40 acres) and participating growers agreed to leave small plots untreated with no sprays against summer larvae until the first damaged apple was observed. These small plots and at least two other areas being treated with standard programs were sampled 2 times/week until damage was detected. After a recommended spray, sampling continued but additional sprays were not recommended unless fruit damaged exceeded 1.5%. Pesticide spray recommendations were followed in only 6 of the 12 total sample-based plots, owing to cutbacks in some growers’ pest management programs resulting from early season hail damage to the crop. Nevertheless, fruit damage at harvest showed no significant differences between the sample-based program and the grower standard preventive program, either in total percent damage or in any USDA grade categories (X-Fancy, Utility, and Cull). A partial budget analysis will be conducted to determine grower returns in the standard vs. research plots.

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