UC IPM: UC Management Guidelines for Western Tussock Moth on Cherry

UC Pest Management Guidelines

Cherry

Western Tussock Moth

Scientific Name: Orgyia vetusta

(Reviewed 4/06, updated 4/06)

In this Guideline:

Description of the pest
Damage
Management

The western tussock moth is an occasional pest in coastal cherry orchards. Tussock moths survive the winter as fuzzy egg masses that female moths cement to their pupal cases and cover with hairs. Mature larvae are gray caterpillars with numerous red, blue, and yellow spots and four white tufts of hair on their backs, two black tufts on their heads, and one on their tail ends. Larvae emerge in March and mature in May; when mature they are 0.5 to 1 inch long. Adults are active from May through July. Males are gray moths; females are grayish white and lack wings. Only one generation is produced each year.

Larvae are insignificant foliar feeders, but may feed on the surface of fruit sufficiently in some years to warrant control measures. Feeding results in shallow, scabby, depressed areas at harvest.

Natural enemies usually keep tussock moth under control.

Biological Control
Natural enemies, including larval parasites (Hyposoter exiguae, H. fugitivus, Dibrachys sp.) and a predatory beetle (Trogoderma sternale), usually keep tussock moth under control.

Cultural Control
Localized infestations can be pruned out and destroyed. Population buildups tend to be localized because the females are flightless.

Organically Acceptable Methods
Biological and cultural controls and sprays of Bacillus thuringiensis and the Entrust formulation of spinosad are acceptable for use on an organically certified crop.

Monitoring and Treatment Decisions
Watch for tussock moth egg cases on leaves and twigs as you monitor orchards in spring before and during bloom. Begin to look for larvae in March. Infestations can be controlled with Bacillus thuringiensis while larvae are small. Petal fall sprays to control other worm problems generally control this pest. Later instars are difficult to control. Localized infestations can be pruned out and destroyed. This pest is cyclic and often controlled by parasitic wasps.

Common name

Amount to Use**

P.H.I.+

(trade name)

(conc.)

(dilute)

(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.

DIAZINON* 50WP

3 lb

1 lb

MODE OF ACTION: An organophosphate (Group 1B)¹ insecticide.

COMMENTS: Avoid drift and tailwater runoff into surface waters. Where cherries are grown adjacent to waterways, do not use this material.

BACILLUS THURINGIENSIS ssp. KURSTAKI#

(various products)

Label rates

MODE OF ACTION: A microbial (Group 11.B2)¹ insecticide.

COMMENTS: Is not harmful to beneficial insects. Apply when larvae are small. Make 2 applications during bloom: the first at early bloom and the second 7–10 days later, but no later than petal fall. Compatible with fungicide sprays. Good coverage is essential.

SPINOSAD

(Entrust)#

1.71–2.5 oz

0.43–0.6 oz

(Success)

6–8 oz

1.5–2 oz

MODE OF ACTION: A microbial (Group 5)¹ insecticide.

COMMENTS: Most effective when applied at petal fall. This product is toxic to bees for 3 hours following treatment; apply in late evening after bees have stopped foraging. Do not apply more than 29 oz/acre/year of Success or 9 oz/acre/year of Entrust.

CARBARYL*

(Sevin) 80S

4 lb

1 lb

(Sevin) XLR PLUS

4 qt

1 qt

MODE OF ACTION: A carbamate (Group 1A)¹ insecticide.

COMMENTS: May cause increased spider mite problems. Do not apply more than 17.5 lb Sevin 80S or 14 qt XLR PLUS/acre/season. The XLR PLUS formulation is less hazardous to honey bees than other formulations if applied from late evening to early morning when bees are not foraging.

**	For concentrate applications, use the amount given in 80–100 gal water/acre, or lower if the label allows; for dilute applications, amount is per 100 gal water to be applied in 300–400 gal water/acre, according to label.
+	Preharvest interval. Do not apply within this many days of harvest.
*	Permit required from county agricultural commissioner for purchase or use.
#	Acceptable for use on organically grown produce.
¹	Modes of action are important in preventing the development of resistance to pesticides. 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. 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 is assigned by IRAC (Insecticide Resistance Action Committee). For additional information, see their Web site at http://www.irac-online.org/.

UC IPM Pest Management Guidelines: Cherry
UC ANR Publication 3440
Insects and Mites
R. A. Van Steenwyk, Insect Biology, UC Berkeley
K. M. Daane, Kearney Agricultural Center, Parlier
J. A. Grant, UC Cooperative Extension, San Joaquin County

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How to Manage Pests

UC Pest Management Guidelines

Cherry

Western Tussock Moth

Scientific Name: Orgyia vetusta

DESCRIPTION OF THE PEST

DAMAGE

MANAGEMENT

PUBLICATION