How to Manage Pests

UC Pest Management Guidelines

Almond

Peach Twig Borer

Scientific name: Anarsia lineatella

(Reviewed 3/09, updated 7/14)

In this Guideline:


Description of the pest

Peach twig borer is a major pest in several tree crops. Adult moths have steel gray mottled forewings. Females lay eggs on twigs, fruit, and leaves. Eggs hatch in 4 to 18 days. Larvae are small, brown caterpillars with white intersegmental bands and a black head capsule. They go through four to five instars. Overwintering larvae are sheltered in tiny cells (hibernacula) that they bore under the bark of limb crotches on 1- to 4-year-old wood, or in bark cracks on larger limbs and the trunk. Pupae are dark brown, without a cocoon, and are found in tree crevices, between hull and shell, in curled leaves, or in debris on the ground. There are four generations per year.

Damage

Larvae damage both growing shoots and nuts, causing shallow channels and surface grooves on the nutmeat. Peach twig borer damage can be masked by navel orangeworm feeding, which often occurs on nuts previously damaged by peach twig borer.

MANAGEMENT

Some orchards will require a treatment for peach twig borer.

  • Use past history, including harvest samples from the previous year, to determine if your orchard will require treatment.
  • Preferred treatment timing is during the dormant period (combined with oil sprays if there is concern for San Jose scale, European red mite, or brown almond mites) or at full bloom and petal fall (may be combined with bloomtime fungicide sprays, but check restrictions on compatibility).
  • Treatments during the dormant season with environmentally-sound insecticides such as spinosad (Entrust, Success) and diflubenzuron (Dimilin) are acceptable.
  • Avoid applications of organophosphates during the dormant season, as these applications threaten water quality when they run off during winter rainfall.
  • Be particularly cautious when using insecticides for peach twig borer during bloom. Insecticide residues may be picked up in the almond pollen, which is taken back to the hive by foraging bees and fed to bee larvae. The impact of these residues on bee larvae is not fully known. Therefore as a guide, applications of insecticides during bloom should be avoided until more is known about the impacts on bee larvae. One exception is Bacillus thuringiensis (Bt), which can be used safely during bloom when pollinators are present.
  • Place pheromone traps out around April 1, and monitor for shoot strikes to catch any in-season problems.
Biological Control

Peach twig borer has about 30 species of natural enemies. Among those commonly found in California are the chalcid wasps Paralitomastix varicornis and Hyperteles lividus. Another commonly found parasite is Macrocentrus ancylivorus, which attacks both peach twig borer and Oriental fruit moth. In some years and orchards, these natural enemies destroy a significant portion of larvae, but they may not reduce twig borer populations below economically damaging levels. Ants, Formica spp., also can be found preying on peach twig borer larvae.

Organically Acceptable Methods

Applications of delayed dormant oil, Bacillus thuringiensis at bloom, or spinosad (Entrust) after bloom are all organically acceptable methods of managing this pest.

Monitoring and Treatment Decisions

Peach twig borer can be successfully managed with environmentally sound insecticides such as spinosad (Entrust, Success), diflubenzuron (Dimilin), Bacillus thuringiensis, methoxyfenozide (Intrepid), and spinetoram (Delegate). Although dormant treatments with organophosphate insecticides are effective and easy to time, they should be avoided because of their potential negative impacts on water quality.

Bloom Sprays

To effectively time bloom sprays with Bacillus thuringiensis, monitor to determine when larvae are emerging from overwintering hibernacula on limb crotches or on tree trunks. The first application must be made when 20 to 40% of larvae have emerged and the second application 7 to 10 days later or when 80 to 100% of larvae have emerged from overwintering hibernacula. If emergence is spread out, a third spray may be needed when emergence finally reaches 80 to 100%. A less-precise method is to apply the first spray between popcorn and full bloom on Nonpareil and a second spray at Nonpareil petal fall, unless there is an extended bloom period, in which case a third application may be needed.

Peach twig borer can be very damaging to developing scaffolds in the second growing season, so a dormant spray is recommended in the first dormant season when monitoring indicates peach twig borer hibernacula.

Spring Sprays

Spring sprays are usually not needed if the dormant spray or bloom spray has been successful, or there is no history of peach twig borer problems. If broad-spectrum insecticides are applied in May, they can cause outbreaks of mites and other secondary pests. Softer pesticides such as spinosad (Entrust, Success), spinetoram (Delegate), chlorantraniliprole (Altacor), and flubendiamide (Belt) have recently become available that have less impact on natural enemies.

Place peach twig borer pheromone traps in orchards, one per 20 acres (but never less than two traps in smaller orchards) by March 20 in the southern Central Valley and April 1 in northern areas. Hang traps 6 to 7 feet high in the northern quadrant of the tree, 1 to 3 feet from the outer canopy. Monitor twice a week; replace pheromone caps at the interval recommended by the manufacturer and replace trap bottoms after 100 moths have been counted and removed.

If shoot strike monitoring (below) indicates treatment is necessary, use trap catches and degree-days to time a May spray. Optimum timing for first-generation larvae (the May spray) is between 400 and 500 degree-days after the first male is trapped in April when using spinosad (Entrust, Success), spinetoram (Delegate), or the organophosphates;when using an IGR (Intrepid), make the application at 300-400 degree-days. Accumulate degree-days for peach twig borer using a lower threshold of 50°F and an upper threshold of 88°F.

Monitor trees of any age for shoot strikes in mid-April. Shoot strikes are easiest to see on young trees and on water sprouts. If several strikes are seen in each tree by late April, a spring spray timed with pheromone traps and degree-days may be required. When examining shoot strikes, determine if they are caused by peach twig borer or Oriental fruit moth by looking for the larvae. Although Oriental fruit moth larvae mine deeper into a shoot than peach twig borer larvae, distinguishing the damage can be difficult. Cut the shoot lengthwise to find the larva and identify it: Oriental fruit moth larvae are white or pink with a brown head and peach twig borer larvae are dark brown with white portions between each body segment and a black head. Also, peach twig borer shoot strikes occur earlier in the season than do Oriental fruit moth strikes.

If navel orangeworm is also a problem, it may be possible to time the May spray to control both pests if navel orangeworm egg hatch occurs at about the same time as optimum time for the peach twig borer spray. If not, wait and spray the navel orangeworm at hullsplit and time the May spray for peach twig borer. (Control of peach twig borer during hullsplit is difficult.)

Common name Amount per acre** R.E.I.‡ P.H.I.‡
(example trade name) (conc.) (dilute)
(hours) (days)

  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.
 
DORMANT
 
A. SPINOSAD
  (Entrust)# 2–3 oz 0.5–0.75 oz 4 1
  (Success) 6–8 oz 1.5–2 oz 4 1
  MODE-OF-ACTION GROUP NUMBER1: 5
  COMMENTS: Apply with a narrow range oil to suppress overwintering mite and scale populations. Does not appear to be disruptive of natural enemies except predaceous thrips and some parasitoids.
 
B. SPINETORAM
  (Delegate WG) 1.5–3.5 oz 0.375–0.9 oz 4 1
  MODE-OF-ACTION GROUP NUMBER1: 5
  COMMENTS: Apply with a narrow range oil to suppress overwintering mite and scale populations. Apply at night to avoid foraging bees.
 
C. NARROW RANGE OIL
  (Superior, Supreme) Label rates See label See label
  MODE OF ACTION: Contact including smothering and barrier effects.
  COMMENTS: Cover all parts of the tree. Do not use oil on water-stressed trees or following periods of dry winds.
  . . . PLUS. . .        
  DIFLUBENZURON*
  (Dimilin 2L) 16 oz 4 oz 12 28
  MODE-OF-ACTION GROUP NUMBER1: 15
  COMMENTS: Apply at volume sufficient to ensure good coverage; use with a narrow range oil at 1.5 to 4% by volume.
 
D. CHLORANTRANILIPROLE (RYNAXYPYR)
  (Altacor) 1.5–3.5 oz 0.375–0.9 oz 4 10
  MODE-OF-ACTION GROUP NUMBER1: 28
  COMMENTS: Apply with a narrow range oil to suppress overwintering mite and scale populations.
 
E. ACETAMPRID
  (Assail 30SG) 5.3–9.6 oz 12 14
  MODE-OF-ACTION GROUP NUMBER1: 4A
  COMMENTS: Apply with a narrow range oil to suppress overwintering mite and scale populations.
 
F. ESFENVALERATE*
  (Asana XL) 8–9.6 oz 2–2.2 oz 12 21
  MODE-OF-ACTION GROUP NUMBER1: 3A
  COMMENTS: Residue has been shown to impact predatory mites into the growing season.
 
G. BIFENTHRIN*
  (Brigade WSB) 8.0–32.0 oz 12 7
  MODE-OF-ACTION GROUP NUMBER1: 3A
  COMMENTS: Pyrethroid insecticides have a broad spectrum of activity against nontarget organisms.
 
H. CYFLUTHRIN*
  (Baythroid XL) 2.8 oz 0.7 oz 12 14
  MODE-OF-ACTION GROUP NUMBER1: 3A
  COMMENTS: Pyrethroid insecticides have a broad spectrum of activity against nontarget organisms.
 
I. LAMBDA-CYHALOTHRIN*
  (Warrior II with Zeon) 1.28–2.56 fl oz 0.32–0.64 fl oz 24 14
  MODE-OF-ACTION GROUP NUMBER1: 3A
  COMMENTS: Pyrethroid insecticides have a broad spectrum of activity against nontarget organisms.
 
DELAYED-DORMANCY OR PINK BUD
 
A. METHOXYFENOZIDE
  (Intrepid 2F) 12 oz 4 14
  MODE-OF-ACTION GROUP NUMBER1: 18
  COMMENTS: Apply in sufficient water to ensure good coverage. Apply with Latron or similar surfactant at 0.125 % volume by volume.
 
B. DIFLUBENZURON*
  (Dimilin 2L) 12 oz 3 oz 12 28
  MODE-OF-ACTION GROUP NUMBER1: 15
  COMMENTS: Apply in sufficient water to ensure good coverage. Apply with Latron or similar surfactant at 0.125 % volume by volume.
 
C. CHLORANTRANILIPROLE (RYNAXYPYR)
  (Altacor) 1.5–3.5 oz 0.375–0.9 oz 4 10
  MODE-OF-ACTION GROUP NUMBER1: 28
  COMMENTS: Apply with a narrow range oil to suppress overwintering mite and scale populations.
 
BLOOM
Note: Additional insecticides are labeled for use during bloom. However, due to concerns over pollinator safety (adult, developing brood in the hive, or both), applications of other insecticides by themselves or in combination with fungicides should be delayed until bloom is complete and hives are removed.
 
A. BACILLUS THURINGIENSIS ssp. KURSTAKI#
  (various products) Label rates 4 0
  MODE-OF-ACTION GROUP NUMBER1: 11A
  COMMENTS: Best if applied by ground, because thorough coverage of the shoot tips is essential. If it must be applied by air because of wet ground or other factors that preclude ground spray, fly about 20 ft over the tree canopy to allow better spray deposition on treetops. Make 2 applications during bloom: the first between popcorn and full bloom on Nonpareil, and the second at Nonpareil petal fall. Compatible with fungicide sprays. Will not control San Jose scale or European red mite eggs, or other pests normally controlled with oil sprays during the dormant or delayed-dormant periods.
 
SPRING
 
A. CHLORANTRANILIPROLE (RYNAXYPYR)
  (Altacor) 3.0–4.5 oz 4 10
  MODE-OF-ACTION GROUP NUMBER1: 28
  COMMENTS: Will not control San Jose scale or European red mite eggs, or other pests normally controlled with oil sprays during the dormant or delayed dormant periods.
 
B. FLUBENDIAMIDE
  (Belt) 3.0–4.0 oz 12 14
  MODE-OF-ACTION GROUP NUMBER1: 28
 
C. SPINETORAM
  (Delegate WG) 3–7 oz 0.75–1.75 oz 4 1
  MODE-OF-ACTION GROUP NUMBER1: 5
  COMMENTS: Apply at night to target active adult moths and to avoid foraging bees.
 
D. EMAMECTIN BENZOATE
  (Proclaim) 3.2–4.8 oz 0.8–1.2 oz See label 14
  MODE-OF-ACTION GROUP NUMBER1: 6
 
E. SPINOSAD
  (Entrust)# 1.25–3 oz 0.3–0.75 oz 4 1
  (Success) 4–8 oz 1–2 oz 4 1
  MODE-OF-ACTION GROUP NUMBER1: 5
  COMMENTS: A fermentation-derived insect control product. Does not appear to be disruptive of natural enemies except predaceous thrips and some parasitoids.
 
F. FLUBENDIAMIDE + BUPROFEZIN
  (Tourismo) 10–14 fl oz 12 60
  MODE-OF-ACTION GROUP NUMBER1: 28 + 16
 
G. BACILLUS THURINGIENSIS ssp. KURSTAKI#
  (various products) Label rates 4 0
  MODE-OF-ACTION GROUP NUMBER1: 11A.
  COMMENTS: Make two applications: one at 300-350 DD from biofix and the other at 450-500 DD. 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.
 
H. CHLORPYRIFOS*
  (Lorsban 4E) 4 pt 24 14
  MODE-OF-ACTION GROUP NUMBER1: 1B
  COMMENTS: Do not apply more than 3 foliar applications per season. Do not allow livestock to graze in treated orchards. Avoid drift or tailwater runoff into surface waters. May applications also control navel orangeworm.
 
I. ACETAMPRID
  (Assail 30SG) 5.3-9.6 oz 12 14
  MODE-OF-ACTION GROUP NUMBER1: 4A
  COMMENTS: Apply with a narrow range oil to suppress overwintering mite and scale populations.
 
** For dilute applications, rate is per 100 gal water to be applied in 300 to 500 gal water/acre, depending on the label; for concentrate applications, use 80 to 100 gal water/acre, or lower if the 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 R.E.I. exceeds the P.H.I. The longer of these two intervals is the minimum time that must elapse before harvest may occur.
# 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 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/.
Not recommended or not on label.

IMPORTANT LINKS

[Precautions]

PUBLICATION

[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Almond
UC ANR Publication 3431

Insects and Mites

  • F. G. Zalom, Entomology, UC Davis
  • C. Pickel, UC IPM Program, UC Cooperative Extension, Sutter/Yuba counties
  • W. J. Bentley, UC IPM Program, Kearney Agricultural Center, Parlier
  • D. R. Haviland, UC IPM Program, UC Cooperative Extension, Kern County
  • R. A. Van Steenwyk, Insect Biology, UC Berkeley
Acknowledgment for contributions to Insects and Mites:
  • R. E. Rice, Kearney Agricultural Center, Parlier
  • L. C. Hendricks, UC Cooperative Extension, Merced County
  • R. L. Coviello, UC Cooperative Extension, Fresno County
  • M. W. Freeman, UC Cooperative Extension, Fresno County

Top of page


Statewide IPM Program, Agriculture and Natural Resources, University of California
All contents copyright © 2014 The Regents of the University of California. All rights reserved.

For noncommercial purposes only, any Web site may link directly to this page. FOR ALL OTHER USES or more information, read Legal Notices. Unfortunately, we cannot provide individual solutions to specific pest problems. See our Home page, or in the U.S., contact your local Cooperative Extension office for assistance.

Agriculture and Natural Resources, University of California

Accessibility   /PMG/r3300211.html revised: July 25, 2014. Contact webmaster.