UC IPM: UC Management Guidelines for Fall Cankerworm on Plum

UC Pest Management Guidelines

Plum

Fall Cankerworm

Scientific name: Alsophila pometaria

(Reviewed 5/06, updated 5/06)

In this Guideline:

Description of the pest
Damage
Management

DESCRIPTION OF THE PEST

Cankerworm larvae have three pairs of prolegs. They are greenish above, with three narrow, whitish stripes and one yellow stripe along the side of the body; underparts are light green. Cankerworms frequently stand on the posterior pair of prolegs in such a way that they resemble a small twig. Fall cankerworms pass the winter in the egg stage. Fall caterpillars hatch and feed on leaves in spring and summer, then pupate and develop into moths in fall. There is one generation per year.

DAMAGE

The larvae are primarily leaf feeders, tending to skeletonize leaves. Occasionally they feed on young fruit by biting deep holes, which later heal, but leave large scarred depressions similar to the injury caused by green fruitworms.

MANAGEMENT

Insecticide sprays applied for other pests often keep these leaf-eating caterpillars in check.

Cultural Control
On small trees, cut out and destroy infested twigs.

Organically Acceptable Methods
Cultural control and Bacillus thuringiensis (Bt) sprays are acceptable for use on organically certified produce.

Treatment Decisions
Bloom or postbloom treatments of Bacillus thuringiensis will control this pest when larvae are present. The Bt program used for peach twig borer control reduces cankerworm damage.

Common name

Amount to Use**

P.H.I.+

(trade name)

(conc.)

(dilute)

(days)

When choosing a pesticide, consider information relating to impact on natural enemies and honey bees, impact of timing on beneficials, and environmental impact.

BLOOM and POSTBLOOM

BACILLUS THURINGIENSIS ssp. KURSTAKI#

(various products)

Label rates

—

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

COMMENTS: Most effective on small caterpillars. Does not destroy natural enemies.

**	For dilute applications, rate is per 100 gal water to be applied in 300-500 gal water/acre, according to label; for concentrate applications, use 80-100 gal water/acre, or lower if the label allows.
+	Preharvest interval. Do not apply within this many days of harvest.
#	Acceptable for use on organically grown produce.
—	Not recommended or not on label.
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: Plum
UC ANR Publication 3462
Insects and Mites
W. J. Bentley, UC IPM Program, Kearney Agricultural Center, Parlier
K. R. Day, UC Cooperative Extension, Tulare County
Acknowledgment for contributions to the insects and mites section:
R. E. Rice, Kearney Agricultural Center, Parlier

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