Articles
Effect of flailing on overwintering filbertworm larvae and aphid parasitoids
Article number
1379_55
Pages
379 – 384
Language
English
Abstract
In Oregon hazelnuts, flail mowing is a common practice for orchard floor management.
Orchards are typically flailed throughout the season to manage weeds, prepare the ground for harvest and manage leaf litter.
A key pest of hazelnuts, Cydia latiferreana (filbertworm), overwinters of the orchard floor as a fifth instar larva protected within a hibernaculum of silk and debris.
Hibernacula are present on the orchard floor from October through May.
Field observations have suggested that flailing is an important management technique for filbertworm populations.
In addition, growers have expressed concern over the effect of flailing on another important insect, Trioxys pallidus. This hymenopteran parasitoid is the primary natural enemy of Myzocallis coryli (filbert aphid), a secondary pest in hazelnut orchards.
It overwinters as an aphid mummy on leaf litter on the orchard floor.
Field trials were conducted from 2018 to 2021 to determine the effect of spring and winter flailing on overwintering populations of both insects.
Spring flailing had a significant effect on overwintering larval survival and pupation in filbertworm.
Across all years, mean larval survival and mean pupation in un-flailed plots were 1.5 times greater than in those flailed in spring.
Both winter and spring flailing had a significant effect on emergence of T. pallidus from overwintering aphid mummies reducing parasitoid emergence by 33 and 40%, respectively.
Growers should consider timing of flailing to maximize impact on filbertworm populations and conserve T. pallidus populations.
In orchards with high aphid pressure, growers should consider providing a refuge from flailing for overwintering parasitoids.
Orchards are typically flailed throughout the season to manage weeds, prepare the ground for harvest and manage leaf litter.
A key pest of hazelnuts, Cydia latiferreana (filbertworm), overwinters of the orchard floor as a fifth instar larva protected within a hibernaculum of silk and debris.
Hibernacula are present on the orchard floor from October through May.
Field observations have suggested that flailing is an important management technique for filbertworm populations.
In addition, growers have expressed concern over the effect of flailing on another important insect, Trioxys pallidus. This hymenopteran parasitoid is the primary natural enemy of Myzocallis coryli (filbert aphid), a secondary pest in hazelnut orchards.
It overwinters as an aphid mummy on leaf litter on the orchard floor.
Field trials were conducted from 2018 to 2021 to determine the effect of spring and winter flailing on overwintering populations of both insects.
Spring flailing had a significant effect on overwintering larval survival and pupation in filbertworm.
Across all years, mean larval survival and mean pupation in un-flailed plots were 1.5 times greater than in those flailed in spring.
Both winter and spring flailing had a significant effect on emergence of T. pallidus from overwintering aphid mummies reducing parasitoid emergence by 33 and 40%, respectively.
Growers should consider timing of flailing to maximize impact on filbertworm populations and conserve T. pallidus populations.
In orchards with high aphid pressure, growers should consider providing a refuge from flailing for overwintering parasitoids.
Publication
Authors
B. Miller, R. Blood, R. Chave, V.M. Walton
Keywords
Cydia latiferreana, Trioxys pallidus, hazelnut, cultural control, conservation biological control
Groups involved
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