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Effect of cover crop on apple leafroller populations, leafroller parasitism and selected arthropods in an orchard managed without insecticides Mullinix, Mark Kent
Abstract
In Washington State the Pandemis leafroller, Pandemis pyrusana (Kerefoll) and obliquebanded leafroller, Choristoneura rosaceana (Harris) are serious pests in orchards in which mating disruption is used to control codling moth, Cydia pomenella. Resistance to organophosphate insecticides exacerbates the problem. Additionally, many question the dependence on insecticides and call for ecologically-based pest management. Parasitoid and predator conservation and augmentation via insecticide reduction and habitat manipulation are tactics proposed to achieve biological control. The objectives of these studies were to: 1) evaluate and compare development of leafroller populations and their biological control by parasitoids in an apple orchard with either a grass or alfalfa cover and in which no insecticides were used; 2) evaluate the influence of cover crops on the general orchard arthropod population in an orchard managed without insecticides; 3) evaluate the use of alfalfa as an orchard cover crop on fruit tree growth and development; and 4) conduct initial testing of strategies for augmenting the leafroller parasitoid Colpoclypeous florus. Experiments were conducted in an East Wenatchee, Washington apple orchard, over four years. Plots were approximately 0.5 ha in size and were sown to either grass cover or alfalfa. Insecticide applications were eliminated. In the absence of broad-spectrum insecticides leafroller populations initially rose to high levels and then dramatically declined. A granulovirus may have been primarily responsible for the decline. Leafroller parasitoids also contributed to leafroller biological control though not extensively. There were no differences in leafroller populations between ground cover treatments. In some instances parasitism was slightly greater in the alfalfa cover plots but this did not seem of any practical significance. Six species were identified in the parasitoid complex. No secondary arthropod pest achieved pest status in either ground cover during the study. Codling moth however became a serious problem in year four. Attempts to augment C. floras populations by seeding parasitized Ancylis comptana fragaria failed. Attempts to establish Xenotemna pallorana on the alfalfa cover to serve as an alternate host for C. floras were likewise unsuccessful. Alfalfa as a cover crop imposed no adverse effects on tree growth and development during the duration of these studies.
Item Metadata
Title |
Effect of cover crop on apple leafroller populations, leafroller parasitism and selected arthropods in an orchard managed without insecticides
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Creator | |
Publisher |
University of British Columbia
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Date Issued |
2003
|
Description |
In Washington State the Pandemis leafroller, Pandemis pyrusana (Kerefoll) and
obliquebanded leafroller, Choristoneura rosaceana (Harris) are serious pests in orchards
in which mating disruption is used to control codling moth, Cydia pomenella. Resistance
to organophosphate insecticides exacerbates the problem. Additionally, many question
the dependence on insecticides and call for ecologically-based pest management.
Parasitoid and predator conservation and augmentation via insecticide reduction and
habitat manipulation are tactics proposed to achieve biological control.
The objectives of these studies were to: 1) evaluate and compare development of
leafroller populations and their biological control by parasitoids in an apple orchard with
either a grass or alfalfa cover and in which no insecticides were used; 2) evaluate the
influence of cover crops on the general orchard arthropod population in an orchard
managed without insecticides; 3) evaluate the use of alfalfa as an orchard cover crop on
fruit tree growth and development; and 4) conduct initial testing of strategies for
augmenting the leafroller parasitoid Colpoclypeous florus. Experiments were conducted
in an East Wenatchee, Washington apple orchard, over four years. Plots were
approximately 0.5 ha in size and were sown to either grass cover or alfalfa. Insecticide
applications were eliminated.
In the absence of broad-spectrum insecticides leafroller populations initially rose to high
levels and then dramatically declined. A granulovirus may have been primarily
responsible for the decline. Leafroller parasitoids also contributed to leafroller biological
control though not extensively. There were no differences in leafroller populations
between ground cover treatments. In some instances parasitism was slightly greater in
the alfalfa cover plots but this did not seem of any practical significance. Six species
were identified in the parasitoid complex. No secondary arthropod pest achieved pest
status in either ground cover during the study. Codling moth however became a serious
problem in year four. Attempts to augment C. floras populations by seeding parasitized
Ancylis comptana fragaria failed. Attempts to establish Xenotemna pallorana on the
alfalfa cover to serve as an alternate host for C. floras were likewise unsuccessful.
Alfalfa as a cover crop imposed no adverse effects on tree growth and development
during the duration of these studies.
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Extent |
14061930 bytes
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Genre | |
Type | |
File Format |
application/pdf
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Language |
eng
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Date Available |
2009-11-27
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Provider |
Vancouver : University of British Columbia Library
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Rights |
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.
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DOI |
10.14288/1.0091658
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URI | |
Degree | |
Program | |
Affiliation | |
Degree Grantor |
University of British Columbia
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Graduation Date |
2004-05
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Campus | |
Scholarly Level |
Graduate
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Aggregated Source Repository |
DSpace
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Item Media
Item Citations and Data
Rights
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.