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UC Pest Management Guidelines


Fruittree leafroller larva.

Apple

Fruittree Leafroller

Scientific name: Archips argyrospila

(Reviewed 8/06, updated 3/09)

In this Guideline:


DESCRIPTION OF THE PEST

Fruittree leafroller overwinters in the egg stage in irregular masses of 30 to 100 eggs cemented over with a secretion. Young larvae are light green caterpillars with black heads and are first seen at bud break. The mature larva is about an inch long and has a green body and black head. The black head helps distinguish fruittree leafroller from other leafrollers. There is one generation per season.

DAMAGE

The fruittree leafroller feeds principally on leaves, but also feeds on blossoms, flower buds, and fruits during bloom. Tiny larvae work their way into opening leaf buds to feed. Once the tree has leafed out, larvae tie up leaves and live within leafrolls, feeding on leaves or fruit. Larvae damage fruit in much the same way as green fruitworms, resulting in shallow cavities in the fruit. Damaged fruits that remain on the tree develop deep bronze-colored scars with roughened, netlike surfaces.

MANAGEMENT

Generally fruittree leafrollers are the first caterpillars seen in samples taken after green tip and have about 2 weeks to feed before the first codling moth spray goes on. Young larvae are easiest to control because they have not yet constructed a nest out of leaves, which protects them from insecticides.

Biological Control

Natural enemies specific for fruittree leafroller are not known, but a number of general predators, such as lacewing and lady beetle larvae, and parasites feed on fruittree leafroller larvae. Although these natural enemies help keep fruittree leafroller populations at low, nondamaging levels; occasional outbreaks still occur, especially in the San Joaquin and inner coastal valleys.

Organically Acceptable Methods

Applications of approved narrow range oil, Bacillus thuringiensis, and the Entrust formulation of spinosad are organically acceptable.

Monitoring and Treatment Decisions

Fruittree leafroller usually is effectively controlled by a dormant oil spray. Make an application thorough enough to cover egg masses. Check results by sampling for leafrollers at green tip. Examine 100 fruit clusters per block. If no worms are found, resample in 1 week. If more than one worm is found, treatment before pink bud may be necessary to prevent damage. Often infestations are usually confined to small, localized areas of the orchard and can be spot treated.

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

  Calculate impact of pesticide on air quality
When choosing a pesticide, consider information relating to impact on natural enemies and honey bees and environmental impact. Not all registered pesticides are listed. Always read label of product being used.
 
DELAYED DORMANT
A. NARROW RANGE OIL# 6 gal 2 gal 4 0
  MODE OF ACTION: Contact including smothering and barrier effects.
  COMMENTS: Check with certifier to determine which products are organically acceptable.
   
B. NARROW RANGE OIL 4 gal 1.5 gal 4 0
  MODE OF ACTION: Contact including smothering and barrier effects.
  . . . PLUS . . .
  CHLORPYRIFOS*      
  (Lorsban) 4EC Label rates 4 days 0
  MODE OF ACTION GROUP NUMBER1: 1B
  COMMENTS: Avoid drift and runoff into surface waters or choose alternative materials. Chlorpyrifos has been found in surface waters at levels that violate federal and state water quality standards.
           
C. METHIDATHION*
  (Supracide) 2EC 3 qt 1 qt 3 days 0
  MODE OF ACTION: An organophosphate (Group 1B)1 insecticide.
         
PINK BUD to PETAL FALL
A. BACILLUS THURINGIENSIS ssp. KURSTAKI#
  (various products) Label rates 4 0
  MODE OF ACTION GROUP NUMBER1: 11.B2
  COMMENTS: Least harmful to beneficials. Bt is a stomach poison and must be consumed by the leafroller; therefore it is most effective when applied during warm, dry weather when larvae are actively feeding. Effective against young larvae. Requires more than 1 treatment; apply second application 7–10 days after first.
   
B. SPINOSAD
  (Entrust)# 2–3 oz 0.5–0.75 oz 4 7
  (Success) 6–10 fl oz 2–3.3 fl oz 4 7
  MODE OF ACTION GROUP NUMBER1: 5
  COMMENTS: Apply at petal fall. To prevent the development of resistance to this product, rotate to a material with a different mode of action after treating two consecutive generations. Do not apply more than 3 sprays/season directed at leafrollers. Do not apply more than 9 oz/acre/crop of Entrust or 29 fl oz of Success/acre/crop.
 
C. METHOXYFENOZIDE
  (Intrepid) 2F 16 fl oz 4 14
  MODE OF ACTION GROUP NUMBER1: 18A
  COMMENTS: Functions both as an ovicide (when applied to eggs and when eggs are laid on residues) and as a larvicide (must be ingested for it to be effective). For each generation, begin applications at early egg hatch before webbing and sheltering begin. Make a second application in 10–14 days. Spray coverage is extremely important. Ground application should use 200 gal water/acre with a sprayer speed of 1.5 mph. The addition of a spray adjuvant is recommended to enhance spray coverage.
   
D. CHLORANTRANILIPROLE
  (Altacor) 3–4.5 oz 4 14
  MODE OF ACTION GROUP NUMBER1: 28
  COMMENTS: Do not apply dilute applications of more than 200 gal/acre; use 100–150 gal/acre for best results.
   
E. SPINETORAM
  (Delegate) WG 4.5–7 oz 4 7
  MODE OF ACTION GROUP NUMBER1: 5
   
** For dilute application, 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 the label allows.
+ 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.
* Permit required from county agricultural commissioner for purchase or use.
# 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/.

[Precautions]

PUBLICATION

[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Apple
UC ANR Publication 3432
Insects and Mites

  • J. L. Caprile, UC Cooperative Extension, Contra Costa County
  • L. R. Wunderlich, UC Cooperative Extension, El Dorado County
  • P. M. Vossen, UC Cooperative Extension, Sonoma and Marin counties
  • W. W. Coates, UC Cooperative Extension, San Benito County
  • H. L. Andris, UC Cooperative Extension, Fresno County
  • L. G. Varela, UC IPM Program, Sonoma County
  • W. J. Bentley, UC IPM Program, Kearney Agricultural Center, Parlier
Acknowledgment for contributions to Insects and Mites:
  • C. Pickel, UC IPM Program, Sutter and Yuba counties

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