How to Manage Pests
UC Pest Management Guidelines
Scientific Name: Archips argyrospila
(Reviewed 6/10, updated 6/10, pesticides updated 9/15)
In this Guideline:
Description of the Pest
Adult fruittree leafroller moths are about 0.5 inch long, with rusty brown wings marked with areas of white and gold. When at rest the adults show the typical bell-shaped pattern common to the family Tortricidae. The eggs are laid in masses on limbs and twigs and are covered with a gray secretion that turns white upon aging. Larvae are green with a black head. The intensity of the green color varies from a light green in young larvae to a darker green as they mature. Fruittree leafroller larvae are difficult to distinguish from the more damaging obliquebanded leafroller larvae.
The fruittree leafroller overwinters in the egg stage. Eggs usually hatch in early spring. Larvae feed within opening buds. As they mature they tie leaves together and feed on leaves, blossoms, and small fruit. Adults emerge in May or June. These adults then lay egg masses that overwinter. There is one generation per year.
Fruittree leafroller damage consists of feeding on blossoms as well as leaves and developing fruit. Rarely are populations heavy enough to cause a reduction in the crop, but this pest can leave unsightly surface feeding scars on the fruit that increase in size as the fruit enlarges, causing it to be culled before packing.
Delayed-dormant treatments and bloom time applications for other pests help keep leafroller populations under control. However, regular monitoring each season is important so that prompt action can be taken if damaging populations develop. In spring, watch for the presence of fruittree leafroller larvae while monitoring for other pests. This is especially important in orchards where bloom time sprays and pheromone confusion are used to control peach twig borer and oriental fruit moth.
A number of parasites, including species of Macrocentrus, Apanteles, and Exochus, attack leafroller larvae. General predators such as lacewings, assassin bugs, and minute pirate bugs may feed on eggs and larvae. Preservation of natural enemy populations is an important part of keeping leafroller numbers low. Use selective materials that are least disruptive of biological control when treating other pests.
Organically Acceptable Methods
Fruittree leafroller can be managed organically with certain oil sprays during the dormant season followed by bloom treatments of Bacillus thuringiensis or the Entrust formulation of spinosad. These treatments are also used to manage other leafrollers and peach twig borer. Always check with your certifier as to which oils are organically acceptable.
Monitoring and Treatment Decisions
Although a separate treatment for fruittree leafroller control is seldom needed, inspect orchards during the dormant period for unusually large numbers of egg masses. Egg masses are about the size of a thumbprint and laid on smooth wood. Also check flowers during bloom for the presence of the fruittree leafroller and other larvae (see EARLY-SEASON MONITORING for details). If damaging populations are observed, a number of environmentally friendly chemicals are effective in controlling this pest, including Bacillus thuringiensis, spinetoram (Delegate), spinosad (Entrust, Success), and methoxyfenozide (Intrepid).
Take a fruit damage sample at harvest to assess the effectiveness of the current year's IPM program and to determine the needs of next year's program. (For procedures seeFRUIT EVALUATION AT HARVEST.) Record results for harvest sample.
UC IPM Pest Management Guidelines: Nectarine
Insects and Mites
K. R. Day, UC Cooperative Extension, Tulare County
Acknowledgment for contributions to Insects and Mites:W. J. Bentley, UC IPM Program, Kearney Agricultural Center, Parlier
R. E. Rice, Kearney Agricultural Center, Parlier
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