How to Manage Pests

UC Pest Management Guidelines

Apricot

Obliquebanded Leafroller

Scientific name: Choristoneura rosaceana

(Reviewed 10/14, updated 10/14)

In this Guideline:


DESCRIPTION OF THE PEST

Obliquebanded leafroller overwinter as third-instar larvae under loose scales or pieces of bark. The overwintered larvae pupate in spring and the first generation of adults emerges in late March or April. Larvae are yellowish green with brown to black heads. As they mature, larvae construct tubular shelters from a single leaf. Adults are reddish brown moths with dark brown bands on the wings. There are two or three generations a year in the Central Valley; it is rarely found in Central Coast orchards.

DAMAGE

Infestations of obliquebanded leafroller can occasionally reach damaging levels in apricots. Larvae feed on flower parts and on fruit early in the season, causing deep depressions that eventually become rough and russeted by harvest.

MANAGEMENT

Delayed dormant treatments and bloom applications for other pests help keep leafroller numbers under control. However, regular monitoring each season is important so that prompt action can be taken if damaging numbers develop.

Biological Control

A number of parasites, including species of Macrocentrus, Cotesia (=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

Use biological controls, delayed-dormant oil sprays combined with the Entrust formulation of spinosad, bloom sprays of Bacillus thuringiensis, and springtime sprays of Entrust on organically grown apricots.

Monitoring and Treatment Decisions

Check the orchard in early spring for the presence of larvae and rolled leaves. The best timing for control of overwintering larvae is at full bloom or early petal fall. Fruit harvested before June 15 will not need additional treatments. Fruit harvested after June 15 will need to be monitored for the summer generation.

Place pheromone traps in the orchard of late-maturing varieties in mid- to late April to determine when to make a summer treatment. Using a lower threshold of 43°F and an upper of 85°F, begin accumulating degree-days when the first moths are trapped (generally late April in the southern San Joaquin Valley to May in the central San Joaquin Valley).

Monitor fruit and leaves for caterpillars when about 500 degree-days have accumulated. Currently there are no treatment thresholds. If a decision is made to apply pesticide, make an application at 600 to 700 degree-days from the biofix (i.e., when the first moths were trapped).

Treatments using degree-day timing benefit management of obliquebanded leafroller on late harvested (June through July) varieties or pest abundance the following year. For fruit harvested in May and June, larval treatment is necessary.

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 (see FRUIT SAMPLING AT HARVEST). Record results (example formPDF).

Common name Amount to Use** REI‡ PHI‡
(Example trade name) (conc.) (dilute)
(hours) (days)

UPDATED: 10/14
Calculate impact of pesticide on air quality
The following are ranked with the pesticides having the greatest IPM value listed first—the most effective and least harmful to natural enemies, honey bees and the environment are at the top of the table. When choosing a pesticide, consider information relating to air and water quality, resistance management, and the pesticide's properties and application timing. Not all registered pesticides are listed. Always read the label of the product being used.
 
BLOOM
 
A. BACILLUS THURINGIENSIS ssp. KURSTAKI#
  (various products) Label rates 4 0
  MODE-OF-ACTION GROUP NUMBER1: 11A
  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. Most effective against young larvae. Requires more than one treatment; apply second application 7 to 10 days after first.
 
B. CHLORANTRANILIPROLE
  (Altacor) 3–4.5 oz 0.75–1.125 oz 4 10
  MODE-OF-ACTION GROUP NUMBER1: 28
  COMMENTS: Do not apply more than 9 oz/acre per year or make more than three applications a year. Do not apply with less than 100 or more than 200 gallons water/acre.
 
C. FLUBENDIAMIDE
  (Belt SC) 3–4 fl oz 0.75–1 fl oz 12 7
  MODE-OF-ACTION GROUP NUMBER1: 28
  COMMENTS: Do not apply more than 4 fl oz/acre per 7-day interval, more than 12 fl oz/acre per season, and more than three times per season.
 
PETAL FALL and AFTER
 
A. SPINOSAD
  (Entrust)# 1.25–2.5 oz 0.42–0.83 oz 4 14
  (Success) 4–8 fl oz 1.3–2.7 fl oz 4 14
  MODE-OF-ACTION GROUP NUMBER1: 5
  COMMENTS: Most effective when applied at petal fall. This product is toxic to bees for 3 hours following treatment; do not spray directly or allow to drift onto blooming crops or weeds where bees are foraging. Apply in the late evening after bees have stopped foraging. Do not apply more than 29 fl oz/acre per year of Success or 9 oz/acre per year of Entrust.
 
B. SPINETORAM
  (Delegate WG) 4.5–7 oz 1.125–1.75 oz 4 14
  MODE-OF-ACTION GROUP NUMBER1: 5
  COMMENTS: This product is toxic to bees for 3 hours following treatment; do not spray directly or allow to drift onto blooming crops or weeds where bees are foraging. Apply in the late evening after bees have stopped foraging. Do not apply more than 28 oz/acre per year or make more than four applications per year.
 
C. CHLORANTRANILIPROLE
  (Altacor) 3–4.5 oz 0.75–1.125 oz 4 10
  MODE-OF-ACTION GROUP NUMBER1: 28
  COMMENTS: Do not apply more than 9 oz/acre per year or make more than three applications a year. Do not apply with less than 100 or more than 200 gallons water/acre.
 
D. FLUBENDIAMIDE
  (Belt SC) 3–4 fl oz 0.75–1 fl oz 12 7
  MODE-OF-ACTION GROUP NUMBER1: 28
  COMMENTS: Do not apply more than 4 fl oz/acre per 7-day interval, more than 12 fl oz/acre per season, and more than three times per season.
 
E. METHOXYFENOZIDE
  (Intrepid 2F) 8–16 fl oz 2–4 fl oz 4 14
  MODE-OF-ACTION GROUP NUMBER1: 18
  COMMENTS: Do not apply more than 16 fl oz/acre per application or more than 64 fl oz/acre per season.
 
F. PHOSMET
  (Imidan 70-W) 2.125–4.25 lb 1 lb 7 days 14
  MODE-OF-ACTION GROUP NUMBER1: 1B
 
G. DIAZINON*
  (Diazinon 50W) 1 lb/100 gal 4 days 21
  MODE-OF-ACTION GROUP NUMBER1: 1B
  COMMENTS: Avoid drift and tailwater runoff into surface waters. Where apricots are grown adjacent to waterways, do not use this material. Do not apply more than 4 lbs product per application.
 
** For concentrate applications, use the amount given in 80 to 100 gal water/acre or lower if the label allows; for dilute application, amount is per 100 gal water to be applied in 300 to 400 gal water/acre, according to label.
Restricted entry interval (REI) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Preharvest interval (PHI) 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.
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 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 website at http://www.irac-online.org/.
* Permit required from county agricultural commissioner for purchase or use.

IMPORTANT LINKS

[Precautions]

PUBLICATION

[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Apricot
UC ANR Publication 3433

Insects and Mites

W. W. Coates, UC Cooperative Extension, San Benito County
R. A. Van Steenwyk, Insect Biology, UC Berkeley
W. J. Bentley, UC IPM Program, Kearney Agricultural Center, Parlier
K. R. Day, UC Cooperative Extension, Tulare County
K. A. Kelley, UC Cooperative Extension, Stanislaus County
J. L. Caprile, UC Cooperative Extension, Contra Costa County

Acknowledgment for contributions to Insects and Mites:
L. C. Hendricks, UC Cooperative Extension, Merced County

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