How to Manage Pests

UC Pest Management Guidelines

Tomato

Green Peach Aphid and Other Early-Season Aphids

Scientific Names: Myzus persicae and others

(Reviewed 12/13, updated 12/13)

In this Guideline:


Description of the Pests

The green peach aphid and several other species are most commonly found on tomatoes early in the season. The green peach aphid is slender, dark green to yellow, with indefinite darker stripes on the abdomen, and no waxy bloom. This aphid is primarily an early-season pest and may transmit virus diseases to tomatoes.

Damage

Green peach aphid infestations may result in wilting, but this damage is usually not of great concern unless the crop is water-stressed. Research indicates that early-season infestations may delay maturity but usually do not result in yield loss unless other factors are also present that enhance the injury. More importantly, these aphids vector pathogens such as Alfalfa mosaic virus.

Management

Conserve natural enemies by avoiding early-season use of disruptive insecticides. If virus transmission is a major concern, it may be economical to reduce or delay the early-season influx and buildup of aphid populations with the use of reflective mulches in fresh market tomatoes. These aphids do not usually require treatment.

Biological Control

Many parasites and predators attack aphids. Among the more common predators are lady beetles and their larvae, lacewing larvae, and syrphid fly larvae. Populations of green peach aphids are reduced in winter by a parasitic fungus, Entomophthora aphidis. Many materials available for aphid control are highly disruptive of natural enemy populations.

Cultural Control

Winged aphids are repelled by silver- or aluminum-colored mulches, which can significantly reduce colonization and delay the buildup of damaging numbers by 4 to 6 weeks. If there is a high probability of severe virus pressure, place reflective polyethylene mulches on planting beds before seeding or transplanting. While this approach is mainly effective in delaying or reducing the incidence of virus diseases transmitted by winged aphids and whiteflies, reflective mulches can also delay the buildup of wingless aphids that arise as a result of colonization by winged individuals. The mulches lose their effectiveness when more than 60% of the surface is covered by foliage. Therefore, they are effective only for the first few weeks after seedling emergence or transplanting of either spring or fall tomatoes.

Organically Acceptable Methods

Cultural and biological controls and sprays of insecticidal soap, pyrethrin, or thyme oil are acceptable for use on organically certified produce.

Monitoring and Treatment Decisions

Green peach aphids may move into early-season tomato seedlings but rarely require treatment. Early-season aphids have many natural enemies, including lady beetles, lacewings, syrphids, and parasites that frequently bring them under control later in the season.

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. SPIROTETRAMAT
  (Movento) 4–5 fl oz 24 1
  MODE-OF-ACTION GROUP NUMBER1: 23
 
B. PYMETROZINE
  (Fulfill) 2.75 oz 12 0
  MODE-OF-ACTION GROUP NUMBER1: 9B
  COMMENTS: Thorough spray coverage is essential for good control.
 
C. THIAMETHOXAM
  (Actara) 3–5.5 oz 12 0
  (Platinum) 5–11 fl oz 12 30
  MODE-OF-ACTION GROUP NUMBER1: 4A
  COMMENTS: Do not spray directly or allow to drift onto blooming crops or weeds where bees are foraging.
 
D. FLONICAMID
  (Beleaf 50SG) 2–2.8 oz 12 0
  MODE-OF-ACTION GROUP NUMBER1: 9C
 
E. ACETAMIPRID
  (Assail 70WP) 1.2 oz 12 7
  MODE-OF-ACTION GROUP NUMBER1: 4A
 
F. IMIDACLOPRID
  (Admire Pro) 7–10.5 fl oz 12 21
  MODE-OF-ACTION GROUP NUMBER1: 4A
  COMMENTS: Effective against all early season aphid species. Most effective when soil or drip applied before or soon after transplanting. Do not apply to vegetables grown for seed.
 
G. DIMETHOATE      
  (Dimethoate 2.67EC) 1.5 pt 48 7
  (Dimethoate 400) 1 pt 48 7
  MODE-OF-ACTION GROUP NUMBER1: 1B
  COMMENTS: Do not use this product if leafminers are present because it is destructive of their parasites. Do not spray directly or allow to drift onto blooming crops or weeds where bees are foraging.
 
H. OXAMYL*
  (Vydate L) 2–4 pt 48 3
  MODE-OF-ACTION GROUP NUMBER1: 1A
  COMMENTS: Do not use if psyllids are in the field as carbamates tend to promote development of their populations.
 
J. MALATHION Label rates 12 1
  MODE-OF-ACTION GROUP NUMBER1: 1B
  COMMENTS: Do not use this product if leafminers are present because it is destructive of their parasites.
 
K. PYRETHRIN#
  (PyGanic 1.4ECII) Label rates 12 0
  MODE-OF-ACTION GROUP NUMBER1: 3
  COMMENTS: Short residual material. Always buffer pyrethrin to pH 5.5 or lower.
 
L. THYME OIL#
  (Proud) Label rates 0 0
  MODE OF ACTION: Contact including smothering and barrier effects.
  COMMENTS: Short residual material. Research has not been conducted against green peach aphid in California, but it has been shown to be effective against melon aphid. Do not use if sulfur was applied recently or will be in the near future.
 
M. INSECTICIDAL SOAP# 2.5 oz/gal water 12 0
  (M-Pede)
  MODE OF ACTION: A contact insecticide with smothering and barrier effects.
  COMMENTS: Can be used to reduce less than damaging populations, particularly when parasite activity is noted. Control is insufficient, however, when there is a high risk of virus transmission.
 
** 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/.

IMPORTANT LINKS

[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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