How to Manage Pests

UC Pest Management Guidelines

Strawberry

Garden Tortrix

Scientific Name: Ptycholoma (=Clepsis) peritana

(Reviewed 6/08, updated 6/08)

In this Guideline:


DESCRIPTION OF THE PEST

The adult has the typical bell-shaped tortricid moth wings while at rest. It is buff-brown and about 0.25 inch (6 mm) long. Each of the forewings is marked with a dark brown diagonal stripe and a marginal spot producing a chevron pattern when at rest. The anterior edge of the brown stripe is bordered by a faint whitish line. This character and the overall lighter color distinguishes adult garden tortrix from moths of the orange tortrix.

The slender larvae are nearly 0.5 inch (12 mm) long when mature. Larvae have light brown-green bodies and light brown heads. The head has a small, distinct dark brown spot on each side. Larvae and pupae overwinter in trash around the base of the plant.

Adults aren't usually seen until March or April. Larvae hatching from eggs laid in spring on older leaves move down into the trash where they feed on dead and decaying leaves. They construct shelters by tying bits of trash together. As a result of overlapping generations, all stages are generally present in spring and summer.

DAMAGE

Larvae feed on dead and decaying leaves and fruit most of the time and generally cause no significant damage. However, as the population increases and the plant canopies close in, more ripening berries settle down into the trash among the tortrix larvae. When this happens, larvae will often spin a nest in creases along the berry's surface and may chew small, shallow holes in the berry, incidental to their scavenging. Thus, with the higher populations often attained by late spring or early summer, significant fruit losses can result from both larval contamination and secondary rots invading the feeding holes.

Contamination of South Coast fields just before the berries are sent to the processors during late June and July can be a serious problem. Up until the point when garden tortrix begins feeding on or webbing against the fruit, this insect serves a valuable function in breaking down and recycling old leaf and fruit litter.

MANAGEMENT

In areas with a chronic tortrix problem, such as the South Coast, it may be feasible to remove accumulated trash in spring around the plants with either blowers or suction devices to limit the potential for a large population buildup. In severe situations, extra help may be required to sort out contaminated or damaged berries during harvest.

Treatments may be required in May to early July if large populations are present, but larvae are difficult to control with sprays because they are located in the litter beneath the protective canopy of strawberry leaves. Directed sprays that penetrate the foliage canopy at sufficient volume are recommended. Because of overlapping generations, there is no best timing period.

Organically Acceptable Methods
Cleaning strawberry fields of dead vegetation as well as sprays of Bacillus thuringiensis and the Entrust formulation of spinosad are acceptable for use on organically certified strawberries.

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

Calculate impact of pesticide on air quality
Bee precaution pesticide ratings
The following materials are listed in order of usefulness in an IPM program, taking into account efficacy and impact on natural enemies and honey bees. When choosing a pesticide, also consider information relating to environmental impact. Not all registered pesticides are listed. Always read label of product being used.
 
A. SPINOSAD
  (Entrust)# 1.25–1.5 oz 4 1
  (Success) 6 fl oz 4 1
  MODE OF ACTION GROUP NUMBER1: 5
  COMMENTS: Most effective against younger larvae. Rotate to an insecticide with a different mode of action after two successive applications. Maintaining proper pH of the spray tank water is critical for maximum efficacy.
 
B. BACILLUS THURINGIENSIS ssp. KURSTAKI#
  (various products) Label rates 4 0
  MODE OF ACTION GROUP NUMBER1: 11.B2
  COMMENTS: Treat when armyworms are still small. To be effective, Bt must be applied no later than the 2nd instar.
 
C. METHOXYFENOZIDE
  (Intrepid 2F) 6­–12 fl oz 4 3
  MODE OF ACTION GROUP NUMBER1: 18
  COMMENTS: Use allowed under a Supplemental Label.
 
D. DIAZINON* 12.75 fl oz/100 gal water 3 days 5
  MODE OF ACTION GROUP NUMBER1: 1B
  COMMENTS: Do not allow this material to run off into surface waters.
 
+ 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.
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: Strawberry
UC ANR Publication 3468

Insects and Mites

  • F. G. Zalom, Entomology, UC Davis
  • M. P. Bolda, UC Cooperative Extension, Santa Cruz County
  • S. K. Dara, UC Cooperative Extension, Santa Barbara County
  • S. Joseph, UC Cooperative Extension, Monterey County
Acknowledgment for contributions to the Insects and Mites:
  • P. A. Phillips, UC IPM Program and UC Cooperative Extension, Ventura County
  • N. C. Toscano, Entomology, UC Riverside

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