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UC Pest Management Guidelines


Adult lygus bug, Lygus hesperus.

Tomato

Lygus Bugs

Scientific name: Lygus hesperus and others

(Reviewed 1/08, updated 1/08)

In this Guideline:


DESCRIPTION OF THE PESTS

Adults are yellowish, brownish, or greenish bugs, about 0.3 inch (7–8 mm) in length, with a conspicuous triangle in the center of the back that is tinged brown, red, or yellow. Nymphs resemble adults, but are uniformly pale green with red-tipped antennae and have no wings. Lygus feed on the fruit or seeds of many flowering plants, including alfalfa and safflower. They can move to tomatoes when their primary hosts dry or are disturbed, such as when alfalfa is cut, safflower dries, or weedy fields of sugar beets are harvested.

For additional information on identifying lygus bugs, see A Field Key to the Most Common Lygus Species Found in Agronomic Crops of the Central San Joaquin Valley of California, UC ANR Publication 8104.

DAMAGE

On the surface of the fruit, lygus bug damage is similar to that of stink bug damage immediately after feeding. The area below the feeding site, however, dries instead of becoming corky, causing the surface of the fruit to crack slightly. Therefore, damage is not as apparent. Lygus feeding has not been associated with the transmission of yeast and fungal pathogens.

MANAGEMENT

Treatment is not recommended for tomatoes to be used for paste or juice. However, if large numbers of lygus are present in fields intended for fresh market or whole pack processing, treatment may be warranted. Check with your processor regarding the significance of lygus damage to their product.

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

  Calculate impact of pesticide on air quality
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. FENPROPATHRIN*
  (Danitol) 2.4 EC 10.66 fl oz 24 3
  MODE OF ACTION GROUP NUMBER1: 3
  COMMENTS: Do not use this product if leafminers are present because it is destructive of their parasites. Do not exceed 2.66 pt/acre/season.
 
B. ENDOSULFAN*
  (Thionex) 3 EC 0.66 qt 24 2
  MODE OF ACTION GROUP NUMBER1: 2A
  COMMENTS: Ground application recommended. Availability in many areas limited because of label
restrictions for fields near waterways.
 
C. METHOMYL*^
  (Lannate) 90WSP 0.5–1 lb 48 1
  (Lannate LV) 1.5–3 pt 48 1
  MODE OF ACTION GROUP NUMBER1: 1A
  COMMENTS: This material will also control armyworm and cabbage looper. 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.
 
D. 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.
 
E. DIMETHOATE
  (Dimethoate) E267 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.
 
 
**  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.
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/.
^ Do not apply when bees are present.

[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 County
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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