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UC Pest Management Guidelines


Fruittree leafroller larva.

Nectarine

Fruittree Leafroller

Scientific Name: Archips argyrospila

(Reviewed 6/10, updated 6/10)

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.

DAMAGE

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.

MANAGEMENT

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.

Biological Control
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, see FRUIT EVALUATION AT HARVEST. Record results (115 KB, PDF) for harvest sample.

Common name Amount/Acre** R.E.I.+ P.H.I.+
(trade name) (conc.) (dilute) (hours) (days)

  Calculate impact of pesticide on air quality
The following materials are listed in order of usefulness in an IPM program, taking into account efficacy, impact on natural enemies and honey bees, and impact of the timing on beneficials. When choosing a pesticide, also consider information relating to environmental impact. Not all registered pesticides are listed. Always read label of product being used.
 
DORMANT or DELAYED DORMANT
A. NARROW RANGE OIL#
  (440 or higher) 4–6 gal 1–1.5 gal 4 0
  MODE OF ACTION: Contact including smothering and barrier effects.
  COMMENTS: Choose a narrow range oil with a 50% distillation point of 440 or higher for dormant season use. Always check with your certifier as to which oils are organically acceptable. Oil used alone will provide only partial control. Best when followed by an application of Bacillus thuringiensis or other environmentally sound insecticides at bloom.
 
B. NARROW RANGE OIL
  (440 or higher) 4–6 gal 1–1.5 gal 4 0
  MODE OF ACTION: Contact including smothering and barrier effects.
  . . . PLUS . . .
  DIFLUBENZURON*
  (Dimilin 2L) 12 oz 3 oz 12 0
  MODE OF ACTION GROUP NUMBER1: 15
  COMMENTS: Apply in sufficient water to ensure good coverage. Choose a narrow range oil with a 50% distillation point of 440 or higher for dormant season use. Apply with narrow range oil at 1.5% oil by volume.
  . . . or . . .
  SPINOSAD
  (Entrust)# 1.25–2.5 oz 0.3–0.6 oz 4 1
  (Success) 4–8 oz 1–2 oz 4 1
  MODE OF ACTION GROUP NUMBER1: 5
  . . . or . . .
  SPINETORAM
  (Delegate WG) 3 oz 0.75 oz 4 1
  MODE OF ACTION GROUP NUMBER1: 5
 
BLOOM
A. SPINETORAM
  (Delegate WG) 4.5–7 oz 1.125–1.75 oz 4 1
  MODE OF ACTION GROUP NUMBER1: 5
 
B. SPINOSAD
  (Entrust)# 1.71–2.5 oz 0.43–0.6 oz 4 1
  (Success) 6–8 oz 1.5–2 oz 4 1
  MODE OF ACTION GROUP NUMBER1: 5
  COMMENTS: Most affective when applied at petal fall. This product is toxic to bees for 3 hours following treatment; apply in the late evening after bees have stopped foraging. Do not apply more than 29 oz/acre/year of Success or 9 oz/acre/year of Entrust.
 
C. METHOXYFENOZIDE
  (Intrepid 2F) 8–16 oz 2–4 oz 4 7
  MODE OF ACTION GROUP NUMBER1: 18
  COMMENTS: Apply at petal fall. Do not apply more than 16 fl oz/acre/application or 64 fl oz/acre/season.
 
D. CHLORANTRANILIPROLE
  (Altacor) 3–4.5 oz 0.75–1.125 oz 4 10
  MODE OF ACTION GROUP NUMBER1: 28
  COMMENTS: Do not used more than 4.5 fl oz/acre/application or more than 9 fl oz/acre/season.
 
E. BACILLUS THURINGIENSIS ssp. KURSTAKI#
  (various products) Label rates 4 0
  MODE OF ACTION GROUP NUMBER1: 11
  COMMENTS: Make two applications during bloom: the first between popcorn and the beginning of bloom and the second 7–10 days later, but no later than petal fall. Compatible with fungicide sprays, and can be tank mixed with them. Good coverage is essential. Ground application using a concentrate rate (80–100 gal water maximum) is preferred. If aerial applications must be made because conditions do not permit ground application, a concentrate rate (5 gal or less) is preferred. Fly material on at a height of about 20 ft over the canopy using appropriate nozzles to allow better deposition on the treetops. Precede this treatment with an oil spray during the delayed dormant season to control San Jose scale and European red mite eggs
 
** For dilute applications, rate is per 100 gal water to be applied in 300-500 gal water/acre, according to label; for concentrate applications, use 80-100 gal water/acre, or lower if label allows.
* Permit required from county agricultural commissioner for purchase or use.
+ Restricted entry interval (R.E.I.) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Preharvest interval (P.H.I.) is the number of days from treatment to harvest. In some cases the REI exceeds the PHI. The longer of two intervals is the minimum time that must elapse before harvest.
# Acceptable for use on organically grown produce.
Not recommended or not on label.
1 Rotate chemicals with a different mode-of-action Group number, and do not use products with the same mode-of-action Group number more than twice per season to help prevent the development of resistance. For example, the organophosphates have a Group number of 1B; chemicals with a 1B Group number should be alternated with chemicals that have a Group number other than 1B. Mode of action Group numbers are assigned by IRAC (Insecticide Resistance Action Committee). For additional information, see their Web site at http://www.irac-online.org/.

IMPORTANT LINKS

[Precautions]

PUBLICATION

[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Nectarine
UC ANR Publication 3451
Insects and Mites
W. J. Bentley, UC IPM Program, Kearney Agricultural Center, Parlier
K. R. Day, UC Cooperative Extension, Tulare County
Acknowledgment for contributions to Insects and Mites:
R. E. Rice, Kearney Agricultural Center, Parlier

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