How to Manage Pests

UC Pest Management Guidelines

Cotton

Cutworms

Scientific Names:
Black cutworm: Agrotis ipsilon
Granulate cutworm: Agrotis subterranea
Variegated cutworm: Peridroma saucia

(Reviewed 5/13, updated 5/13)

In this Guideline:

DESCRIPTION OF THE PESTS

Cutworm larvae vary in color, but they are usually dull gray, blend in with the soil, and always appear smooth skinned. The black cutworm larva is gray to dark brown above and has a greasy appearance. Faint light stripes run lengthwise down the body. It lives in soil and is usually not seen until damage is found. The granulate cutworm is about an inch long when mature, dark gray in color, and the surface of its body is covered with black granules. It lives in the soil and cuts plants off below ground. The variegated cutworm is a dark gray caterpillar with a light stripe on the side and small yellow to orange spots on top of the abdominal segments.

Damage

Cutworm larvae chew young plants off at the base at or near ground level. Damage is usually limited to certain parts of a field and may reoccur each season in the same place. Usually several plants in the same row are damaged.

Management

Cutworms may become a problem if good field sanitation practices are not used and residue from a previous crop is allowed to remain in the field over the winter.

Cultural Control

Allow time for previous crop residues to decompose and destroy vegetation from weeds and cover crops for at least 3-4 weeks before planting to minimize the cutworm problem.

Monitoring and Treatment Decisions

Watch for cutworm injury by walking the field during the seedling stage. Pay special attention to field edges and any low or weedy areas. Use spot treatments, preferably with a ground rig, where treatment is necessary.

Common name		Amount per acre**	R.E.I.‡	P.H.I.‡
(example trade name)			(hours)	(days)
The following 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, also 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.	CHLORPYRIFOS*
	(Lorsban Advanced)	1.5–2 pt	24	14
	SELECTIVITY: Moderate
	PERSISTENCE: Pest: Moderate NE:2 Short
	MODE OF ACTION GROUP NUMBER1: 1B
	COMMENTS: Do not graze or feed trash to livestock.
B.	INDOXACARB
	(Steward)	Label rates	12	14
	SELECTIVITY: Moderate
	PERSISTENCE: Pest: Moderate NE:2 Moderate
	MODE OF ACTION GROUP NUMBER1: 22A
	COMMENTS: An oxadiazine. Use if granulate cutworm (Agrotis subterranea) is present.
**	Mix with sufficient 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/.
2	NE = natural enemies

PUBLICATION

UC IPM Pest Management Guidelines: Cotton
UC ANR Publication 3444

Insects and Mites

• L. D. Godfrey, Entomology, UC Davis
• P. B. Goodell, UC IPM Program and Kearney Agricultural Research and Extension Center, Parlier
• E. T. Natwick, UC Cooperative Extension - Desert Research and Extension Center, Imperial County
• D.R. Haviland, UC Cooperative Extension, Kern County and UC IPM Program

Acknowledgment for contributions to Insects and Mites:

• E. E. Grafton-Cardwell, Kearney Agricultural Research and Extension Center, Parlier
• N. C. Toscano, Entomology, UC Riverside

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