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How to Manage Pests

UC Pest Management Guidelines

| More pests | More crops | About guidelines |

Cabbage looper larva.

Tomato

Loopers

Scientific names: Alfalfa looper: Autographa californica
Cabbage looper: Trichoplusia ni

(Reviewed 1/08, updated 1/08)

In this Guideline:

DESCRIPTION OF THE PESTS

Looper caterpillars are easily recognized because they crawl by arching their backs. Looper eggs are laid singly on the undersurface of mature leaves. They are similar to fruitworm eggs, but flatter, and have finer ridges radiating from the top.

DAMAGE

Loopers feed only on foliage, not on fruit. Damage is usually insufficient to require control measures so treatment is rarely recommended.

MANAGEMENT

Although common in tomato fields, looper populations are generally kept below damaging levels by naturally occurring parasites and a viral disease. Moderate numbers of loopers are considered more beneficial than harmful because they serve as alternative hosts for parasitic wasps that also attack tomato fruitworms and other pest caterpillars. Treatment is only necessary if feeding is extensive enough that sunburn of the fruit is a concern. Consider nondisruptive insecticides such as Bacillus thuringiensis to protect natural enemies.

Biological Control
There are several important naturally occurring parasites that help control loopers in tomatoes. One of these is Hyposoter exiguae, which also attacks tomato fruitworms and armyworms. Another parasitic wasp, Copidosoma truncatellum, commonly kills looper and other larvae by attacking the overwintering pupae. In southern California, looper eggs are often killed by Trichogramma; Trichogramma released for tomato fruitworm control often parasitize cabbage looper eggs as well. Alfalfa and cabbage loopers are also subject to disease caused by a nuclear polyhedrosis virus. Conserve these parasites by not treating with disruptive pesticides, particularly early in the season.

Organically Acceptable Methods
Biological control and sprays of Bacillus thuringiensis or the Entrust formulation of spinosad are acceptable for use on an organically certified crop.

Monitoring and Treatment Decisions
Determine the extent of damage in the field. If damage is severe enough to expose fruit to sunburn, treat mid- to late-season foliage to maintain the plant canopy. Spot treat only severely infested areas.

Common name Amount/Acre** R.E.I.+ P.H.I.+
(trade name)   (hours) (days)
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. BACILLUS THURINGIENSIS ssp. KURSTAKI#
  (various products) Label rates 4 0
  MODE OF ACTION GROUP NUMBER1: 11.B2
  COMMENTS: This material does not destroy natural enemies of tomato pests. It will also control hornworms and to some extent beet armyworms and tomato fruitworms.
 
B. INDOXACARB
  (Avaunt) 3.5 oz 12 3
  MODE OF ACTION GROUP NUMBER1: 22
 
C. SPINOSAD
  (Entrust)# 1–2 fl oz 4 1
  (Success) 3–6 fl oz 4 1
  MODE OF ACTION GROUP NUMBER1: 5
  COMMENTS: For resistance management, do not apply more than 3 times in any 21 day period. Do not apply more than 0.45 lb a.i./acre/season.
 
D. ESFENVALERATE*^
  (Asana XL) 0.66EC 5.8–9.6 fl oz 12 1
  MODE OF ACTION GROUP NUMBER1: 3
  COMMENTS: Do not feed or graze livestock on treated vines. Do not exceed 0.5 lb a.i./acre/season. Note: some bleaching or spotting may occur on the foliage of young plants. This does not affect yield or fruit quality. Do not use this product if leafminers are present because it is destructive of their parasites.
 
 
**  See label for dilution rates.
+ 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 until harvest can take place. 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 take place.
* Permit required from county agricultural commissioner for purchase or use.
^ Do not apply when bees are present.
# 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/.

[Precautions]

PUBLICATION

[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Tomato
UC ANR Publication 3470
Insects and Mites
F. G. Zalom, Entomology, UC Davis
J. T. Trumble, Entomology, UC Riverside
C. F. Fouche, UC Cooperative Extension, San Joaquin Co.
C. G. Summers, Entomology, UC Davis/Kearney Agricultural Center, Parlier
Acknowledgments for contributions to the insects and mites section:
N. C. Toscano, Entomology, UC Riverside

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Statewide IPM Program, Agriculture and Natural Resources, University of California
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