How to Manage Pests

UC Pest Management Guidelines

DESCRIPTION OF THE PEST

Saltmarsh caterpillar larvae are hairy and gray when first hatched, then darken to yellow, brownish, or almost black with yellow lines. They are covered with reddish or black hairs, and can be up to 2 inches long when fully grown. Eggs are spherical, whitish, somewhat flattened, about 0.03 inch in diameter, and found in clusters on the undersurface of leaves.

DAMAGE

In the southern San Joaquin Valley, saltmarsh caterpillars are occasional pests that feed on foliage. They are primarily a problem in fall when neighboring cotton fields are defoliated.

MANAGEMENT

Cultural Control

Ditch or trench around the edges of fields that border cotton.

Organically Acceptable Methods

Cultural control and sprays of the Entrust formulation of spinosad are acceptable for use on organically grown produce.

Monitoring and Treatment Decisions

In fall, if saltmarsh caterpillars are migrating into carrots, a treatment may be necessary.

Common name		Amount/Acre**	R.E.I.+	P.H.I.+
(trade name)			(hours)	(days)
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 the label of the product being used.
A.	SPINOSAD
	(Entrust)#	1–2 fl oz	4	3
	MODE OF ACTION GROUP NUMBER1: 5
	COMMENTS: Do not apply more than 7 oz of Entrust/acre/crop or more than 4 applications/calendar year. Additional applications must be at least 5 days apart. Use allowed under a supplemental label.
B.	CARBARYL*
	(Sevin 80S)	1.25–2.5 lb	12	7
	MODE OF ACTION GROUP NUMBER1: 1A
	COMMENTS: Ground or air application.
**	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 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/.
#	Acceptable for use on organically grown produce.
*	Permit required from county agricultural commissioner for purchase or use.

PUBLICATION

UC IPM Pest Management Guidelines: Carrot
UC ANR Publication 3438

Insects

E. T. Natwick, UC Cooperative Extension, Imperial County
D. R. Haviland, UC IPM Program, Kern County
C. G. Summers, Entomology, Kearney Agricultural Center, Parlier
Acknowledgment for contributions to Insects:
W. E. Chaney, UC Cooperative Extension, Monterey County

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