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How to Manage Pests

UC Pest Management Guidelines


Variegated cutworm larva.

Lettuce

Cutworms

Scientific Names:
Black cutworm: Agrotis ipsilon
Variegated cutworm: Peridroma saucia
Granulate cutworm: Feltia ubterranean

(Reviewed 8/07, updated 10/09)

In this Guideline:


DESCRIPTION OF THE PESTS

Cutworm larvae frequently roll into a C-shape when disturbed. Black cutworm larvae are greasy gray to brown with several black bumps or tubercles on each segment. They may tunnel beneath the soil dragging parts of plants with them. The variegated cutworm larva is from 1.5 to 2 inches long, yellow to brown, with a row of four to six dull yellow or pink diamond-shaped spots down the back. The granulate cutworm varies in color, but is lighter than the black cutworm, and does not tunnel. Adult cutworm moths have dark gray or brown front wings with irregular spots or bands, and lighter hind wings.

DAMAGE

Cutworms usually cut seedlings off at or just below the soil line. They may also bore into heads, and some species may damage leaves.

MANAGEMENT

Before planting, check for cutworms in surrounding weeds. After the crop is up, look around for wilted plants or plants with severed stems. Dig around the base of injured plants and sift soil for these pests. Cutworms hide during the day and are found on the plants mostly at night.

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

  Calculate impact of pesticide on air quality
When choosing a pesticide, consider information relating to the impact on natural enemies and honey bees and environmental impact. Not all registered pesticides are listed. Always read label of product being used.
 
A. CARBARYL
  (Sevin Bait 5%) 30–40 lb 12 See label
  MODE OF ACTION GROUP NUMBER1: 1A
 
B. CYPERMETHRIN*
  (Ammo) Label rates 12 5
  MODE OF ACTION GROUP NUMBER1: 3
  COMMENTS: For use on head lettuce only. Apply through chemigation. Do not use if leafminers are present.
 
C. PERMETHRIN*
  (Ambush, Pounce) Label rates 12 1
  MODE OF ACTION GROUP NUMBER1: 3
  COMMENTS: Do not use if leafminers are present.
 
D. ESFENVALERATE*
  (Asana XL) Label rates 12 7
  MODE OF ACTION GROUP NUMBER1: 3
  COMMENTS: For use on head lettuce only. Do not use if leafminers are present.
 
** Mix with enough water to provide complete coverage.
+ 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: Lettuce
UC ANR Publication 3450
Insects and Other Arthropods
E. T. Natwick, UC Cooperative Extension, Imperial County
Acknowledgment for contributions to Insects and Mites:
W. E. Chaney, UC Cooperative Extension, Monterey County
N. C. Toscano, Entomology, UC Riverside

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