How to Manage Pests

UC Pest Management Guidelines

Tomato

Loopers

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

(Reviewed 12/13, updated 12/13)

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 not serious enough 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. When insecticides are required, 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 lepidopteran 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 when tomatoes are at mid- to late-stage vegetative growth to maintain the plant canopy. Spot treat only severely infested areas.

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

  Calculate impact of pesticide on air quality
The following materials 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.
 
A. BACILLUS THURINGIENSIS spp. KURSTAKI#
  (various products) Label rates 4 0
  MODE-OF-ACTION GROUP NUMBER1: 11A
  COMMENTS: This insecticide is most effective against newly hatched larvae, so proper treatment timing is essential. This insecticide is also somewhat effective on on other lepidopteran pests.
 
B. CHLORANTRANILIPROLE
  (Coragen) 3.5–5 fl oz 4 1
  MODE-OF-ACTION GROUP NUMBER1: 28
  COMMENTS: Can be applied as foliar spray or by drip chemigation. Read label for treatment intervals.
 
C. METHOXYFENOZIDE
  (Intrepid 2F) 8–16 fl oz 4 1
  MODE-OF-ACTION GROUP NUMBER1: 18A
  COMMENTS: Low toxicity to beneficials. Apply at the beginning of egg hatch. When traps indicate moth flights have begun, sample leaves for eggs. Treat when eggs are first detected.
 
D. FLUBENDIAMIDE
  (Synapse WG) 2–3 oz 12 1
  MODE-OF-ACTION GROUP NUMBER1: 28
  COMMENTS: Do not spray directly or allow to drift onto blooming crops or weeds where bees are foraging.
 
E. SPINETORAM
  (Radiant SC) 5–10 fl oz 4 1
  MODE-OF-ACTION GROUP NUMBER1: 5
  COMMENTS: Apply as a foliar spray.
 
F. SPINOSAD
  (Entrust)# 1.25–2.5 fl oz 4 1
  (Success) 4–8 fl oz 4 1
  MODE-OF-ACTION GROUP NUMBER1: 5
  COMMENTS: Use higher rate for larger worms and heavy infestations. Best control is achieved when aimed at newly hatched larvae and coverage is thorough. Less toxic to natural enemies than many other choices. For resistance management, do not apply more than 0.45 lb a.i./acre per season.
 
G. NOVALURON
  (Rimon 0.83EC) 9–12 fl oz 12 1
  MODE-OF-ACTION GROUP NUMBER1: 1A
  COMMENTS: Apply at egg hatch to the second instar. Use higher rates when larvae are large or foliage canopy is tall or dense.
 
H. EMAMECTIN BENZOATE*
  (Proclaim) 2.4–4.8 oz 12 7
  MODE-OF-ACTION GROUP NUMBER1: 6
 
I. INDOXACARB
  (Avaunt) 3.5 oz 12 3
  MODE-OF-ACTION GROUP NUMBER1: 22
 
J. METHOMYL*
  (Lannate SP) 0.5–1 lb 48 1
  MODE-OF-ACTION GROUP NUMBER1: 1A
  COMMENTS: Will also control fruitworm, yellowstriped armyworm, cutworms, and cabbage looper. Primary use of methomyl should be if older larvae, which are difficult to control with other insecticides, are present. Some resistance has been documented. Do not use if psyllids are in the field as carbamates tend to promote development of their populations; also if leafminers are present, it may cause outbreaks by destroying their natural enemies.
 
K. ESFENVALERATE*
  (Asana XL) 5.8–9.6 fl oz 12 1
  MODE-OF-ACTION GROUP NUMBER1: 3A
  COMMENTS: Use only under heavy pest pressure and close to harvest. Some resistance has been documented. May cause outbreaks of Liriomyza spp. Leafminers and tomato russet mite. In some areas where tomatoes are grown, resistance to this material is a problem. Do not spray directly or allow to drift onto blooming crops or weeds where bees are foraging.
 
L. FENPROPATHRIN*
  (Danitol 2.4EC) 10.66 fl oz 24 3
  MODE-OF-ACTION GROUP NUMBER1: 3A
  COMMENTS: Use only under heavy pest pressure and close to harvest. May cause outbreaks of Liriomyza spp. leafminers and tomato russet mites.
 
** 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.
# 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

E. T. Natwick, UC Cooperative Extension, Imperial County
C. S. Stoddard, UC Cooperative Extension, Merced and Madera counties
F. G. Zalom, Entomology, UC Davis
J. T. Trumble, Entomology, UC Riverside
G. Miyao, UC Cooperative Extension, Solano and Yolo counties
J. J. Stapleton, UC IPM Program and Kearney Agricultural Center, Parlier (false chinch bug)
Acknowledgments for contributions to Insects and Mites:
C. G. Summers, Entomology, UC Davis and Kearney Agricultural Center, Parlier
C. F. Fouche, UC Cooperative Extension, San Joaquin County
N. C. Toscano, Entomology, UC Riverside

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