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How to Manage Pests

UC Pest Management Guidelines


Variegated cutworm, Peridroma saucia, larva.

Dry Beans

Cutworms

Scientific names:
Black cutworm: Agrotis ipsilon
Variegated cutworm: Peridroma saucia, and others

(Reviewed 8/07, updated 12/08)

In this Guideline:


DESCRIPTION OF THE PESTS

Adults are moths approximately 1 inch long with a wing span of 1.25 to 2 inches and vary widely in coloration. Eggs are somewhat flattened on top, white to dull or off-white in color, and ribbed. They are generally deposited in massed rows. Eggs may be deposited on crop foliage, but are frequently found on weeds. Fully grown larvae range from 1 to 1.75 inches in length.

Cutworms are most active and cause the most damage during spring and early summer months. The larvae normally hide under debris on the soil surface during the day, but are active, voracious feeders at night. Some cutworms climb into the host plant to feed, but many stay on the ground, cutting seedling host plants off at or just below the soil surface.

DAMAGE

Cutworms cut young plants off at the base or near the ground level. Usually, it is necessary to dig in the soil to find cutworm larvae and to determine the extent of the infestation and the size of the cutworms involved.

MANAGEMENT

Cultural Control
Eliminate weeds 2 weeks before planting both within and adjacent to the field to minimize cutworm problems.

Organically Acceptable Methods
Cultural control is acceptable in an organically certified crop.

Treatment Decisions
Start inspecting plants for cutworm damage along with other pest damage when the crop emerges. If the cutworm population is reducing the plant stand, treat during the seedling stage. Frequently, the damage is most serious at the edges of a field, but stand loss may occur in a spotty pattern throughout the field.

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) 5% Bait 30 lb 12 see label
  MODE OF ACTION GROUP NUMBER1: 1A
  COMMENTS: Ground or air application. Avoid direct application to lakes, streams, ponds. Do not apply when weather conditions favor drift from treated areas. Do not contaminate water, food, or feed when cleaning equipment or disposing of wastes.
 
** Mix with sufficient water to obtain full 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.
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: Dry Beans
UC ANR Publication 3446
Insects and Mites
L. D. Godfrey, Entomology, UC Davis
R. F. Long, UC Cooperative Extension, Yolo County

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