How to Manage Pests

UC Pest Management Guidelines

DESCRIPTION OF THE PEST

Obliquebanded leafroller overwinter as third instar larvae under bud scales. Larvae are yellowish green with brown to black heads. As they mature, larvae construct tubular shelters from a single leaf. There are two generations a year. Periodically, localized infestations of obliquebanded leafroller occur and the larvae of the summer generation can cause serious damage in July and August. Obliquebanded leafroller is rarely a pest in Central Coast orchards.

DAMAGE

Larvae feed on flower parts and on fruit early in the season, causing deep depressions that eventually become rough and russeted by harvest. Damage from the summer generation is usually more serious and results in superficial skin tunnels or small holes near the stem portion of the fruit.

MANAGEMENT

Obliquebanded leafroller can occur in orchards in spring and summer. Summer damage is most commonly seen in orchards where a switch is made to the use of highly selective materials (including mating disruption) against codling moth that do not control obliquebanded leafrollers.

Biological Control
The parasitic wasp Macrocentrus iridescens has been observed attacking obliquebanded leafroller larvae in the Central Valley and in Central Coast and North Coast apple orchards.

Organically Acceptable Methods
Sprays of Bacillus thuringiensis and the Entrust formulation of spinosad are organically acceptable.

Monitoring and Treatment Decisions
The best time to treat obliquebanded leafrollers is in spring, around pink bud, before the larvae are sheltered under leaves and between fruit clusters. Apply materials before bees are placed in orchards or after they are removed. Control overwintering larvae with either a delayed dormant application of oil and insecticide or a bloom application. If orchards have experienced damage from this pest in previous years or if leafrollers were observed in spring, also monitor the summer generation. Take fruit and leaf cluster samples at pink bud and in July and August. Tentative thresholds are two or more live larvae in a 100 fruit cluster sample in spring, and four or more in summer.

Common name		Amount to use**		R.E.I.+	P.H.I.+
(trade name)		(conc.)	(dilute)	(hours)	(days)
When choosing a pesticide, consider information relating to the impact on natural enemies and honey bees Not all registered pesticides are listed. Always read label of product being used. and environmental impact.
DELAYED DORMANT
A.	NARROW RANGE OIL	4 gal	1.5 gal	4	0
	MODE OF ACTION GROUP NUMBER1:Improves translaminar movement and insecticide persistence.
	. . . PLUS . . .
	CHLORPYRIFOS*
	(Lorsban) 4EC	Label rates		4 days	0
	MODE OF ACTION GROUP NUMBER1: 1B
	COMMENTS: Avoid drift and runoff into surface waters or choose alternative materials. Chlorpyrifos has been found in surface waters at levels that violate federal and state water quality standards.
BLOOM
A.	SPINOSAD
	(Entrust)#	2–3 oz	0.5–0.75 oz	4	7
	(Success)	6–10 fl oz	2–3.3 fl oz	4	7
	MODE OF ACTION GROUP NUMBER1: 5
	COMMENTS: Most effective when applied at petal fall. To prevent the development of resistance to this product, rotate to a material with a different mode of action after treating two consecutive generations. Do not apply more than 3 sprays/season directed at leafrollers. Do not apply more than 9 oz/acre/crop of Entrust or 29 fl oz of Success/acre/crop.
B.	BACILLUS THURINGIENSIS ssp. KURSTAKI#
	(various products)	Label rates	—	4	0
	MODE OF ACTION GROUP NUMBER1: 11.B2
	COMMENTS: Least harmful to beneficials. Bt is a stomach poison and must be consumed by the leafroller; therefore it is most effective when applied during warm, dry weather when larvae are actively feeding. Most effective against young larvae. Requires more than 1 treatment; apply second application 7–10 days after first.
C.	METHOXYFENOZIDE
	(Intrepid) 2F	16 fl oz	—	4	14
	MODE OF ACTION GROUP NUMBER1: 18A
	COMMENTS: Functions both as an ovicide (when applied to eggs and when eggs are laid on residues) and as a larvicide (must be ingested to be effective). For each generation, begin applications at early egg hatch before webbing and sheltering begin. Make a second application in 10–14 days. Spray coverage is extremely important. Ground application should use 200 gal water/acre with a sprayer speed of 1.5 mph. The addition of a spray adjuvant is recommended to enhance spray coverage.
D.	CHLORANTRANILIPROLE
	(Altacor)	3–4.5 oz	—	4	14
	MODE OF ACTION GROUP NUMBER1: 28
	COMMENTS: Do not apply dilute applications of more than 200 gal/acre; use 100–150 gal/acre for best results.
E.	SPINETORAM
	(Delegate) WG	4.5–7 oz	—	4	7
	MODE OF ACTION GROUP NUMBER1: 5
**	For dilute application, 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.
+	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.
#	Acceptable for use on organically grown produce.
—	Not recommended or not on label.
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/.

PUBLICATION

UC IPM Pest Management Guidelines: Apple
UC ANR Publication 3432
Insects and Mites
J. L. Caprile, UC Cooperative Extension, Contra Costa County
L. R. Wunderlich, UC Cooperative Extension, El Dorado County
P. M. Vossen, UC Cooperative Extension, Sonoma and Marin counties
W. W. Coates, UC Cooperative Extension, San Benito County
H. L. Andris, UC Cooperative Extension, Fresno County
L. G. Varela, UC IPM Program, Sonoma County
W. J. Bentley, UC IPM Program, Kearney Agricultural Center, Parlier
Acknowledgment for contributions to Insects and Mites:
C. Pickel, UC IPM Program, Sutter and Yuba counties

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