How to Manage Pests

UC Pest Management Guidelines

DESCRIPTION OF THE PEST

Obliquebanded leafroller overwinter as third-instar larvae under bud scales. The overwintered larvae pupate in spring, and the first generation of adults emerges in late April or May. Larvae are yellowish green with brown to black heads. As they mature, larvae construct tubular shelters from a single leaf. Adults are reddish brown moths with dark brown bands on the wings. There are usually two generations a year in the Sacramento Valley and up to three in the San Joaquin Valley.

DAMAGE

Infestations of obliquebanded leafroller can occasionally reach damaging levels in nectarines. Larvae feed on flower parts and on fruit early in the season, causing deep depressions that eventually become rough and russeted by harvest and might be mistaken for flower thrips damage. Because of the high cyanide content of nectarine leaves, larvae generally concentrate their feeding on fruit; consequently, lower numbers of larvae may cause more damage in nectarines than in other crops. This leafroller is more damaging than fruittree leafrollers because it has one to two summer generations.

MANAGEMENT

Delayed dormant treatments and bloom time applications for other pests help keep leafroller populations under control. However, regular monitoring each season is important so that prompt action can be taken if damaging populations develop. Throughout the season, watch for leafrollers while monitoring for other pests. This is especially important in orchards where bloom time sprays and pheromone confusion are used to control peach twig borer and oriental fruit moth.

Biological Control
A number of parasites, including species of Macrocentrus, Cotesia (=Apanteles), and Exochus, attack leafroller larvae. General predators such as lacewings, assassin bugs, and minute pirate bugs may feed on eggs and larvae. Preservation of natural enemy populations is an important part of keeping leafroller numbers low. Use selective materials that are least disruptive of biological control when treating other pests.

Organically Acceptable Methods
Organically acceptable management tools include biological control and sprays of Bacillus thuringiensis or the Entrust formulation of spinosad.

Monitoring and Treatment Decisions
Check the orchard in early spring (March–April) for the presence of larvae and feeding damage on flowers, see EARLY SEASON MONITORING. If damaging populations are observed, a number of environmentally friendly insecticides are effective in controlling this pest, including Bacillus thuringiensis, spinetoram (Delegate), spinosad (Entrust, Success), and methoxyfenozide (Intrepid). The best timing for control of overwintering larvae is at full bloom or early petal fall.

Pheromone traps placed in the orchard in mid-April (see PHEROMONE TRAPS) will help to monitor the population levels of this insect and provide information for management of the summer generations. Based on research done in California pistachio orchards, begin accumulating degree-days as soon as traps begin to catch moths using a lower threshold of 43°F and an upper threshold of 94°F. (For assistance in calculating degree-days, see "Degree-days ".) Make treatments between 600 and 1000 DD.

Examine fruit on trees every week after color break (see PREHARVEST FRUIT SAMPLES) to detect any developing problems in the orchard, and take a fruit damage sample at harvest to assess the effectiveness of the current year's IPM program and to determine the needs of next year's program (see FRUIT EVALUATION AT HARVEST). Record results (115 KB, PDF) for harvest sample.

Common name		Amount to Use**		R.E.I.+	P.H.I.+
(trade name)		(conc.)	(dilute)	(hours)	(days)
The following materials are listed in order of usefulness in an IPM program, taking into account efficacy, impact on natural enemies and honey bees, and impact of the timing on beneficials. When choosing a pesticide, also consider information relating to environmental impact. Not all registered pesticides are listed. Always read label of product being used.
DELAYED DORMANT
A.	NARROW RANGE OIL
	(440 or higher)	4–8 gal	1.5–2 gal	4	0
	MODE OF ACTION: Contact including smothering and barrier effects.
	. . . PLUS . . .
	SPINOSAD
	(Entrust)#	1.25–2.5 oz	0.3–0.6 oz	4	1
	(Success)	4–8 oz	1–2 oz	4	1
	MODE OF ACTION GROUP NUMBER1: 5
	COMMENTS: Choose a narrow range oil with a 50% distillation point of 440 or higher for dormant season use. Always check with your certifier as to which oils are organically acceptable.
	. . . or . . .
	SPINETORAM
	(Delegate) WG	4.5–7 oz	1.125–1.75 oz	4	1
	MODE OF ACTION GROUP NUMBER1: 5
BLOOM
A.	SPINETORAM
	(Delegate) WG	4.5–7 oz	1.125–1.75 oz	4	1
	MODE OF ACTION GROUP NUMBER1: 5
B.	SPINOSAD
	(Entrust)#	1.71–2.5 oz	0.43–0.6 oz	4	1
	(Success)	6–8 oz	1.5–2 oz	4	1
	MODE OF ACTION GROUP NUMBER1: 5
	COMMENTS: Most effective when applied at petal fall. This product is toxic to bees for 3 hours following treatment; apply in the 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.
C.	CHLORANTRANILIPROLE
	(Altacor)	3–4.5 oz	0.75–1.125 oz	4	10
	MODE OF ACTION GROUP NUMBER1: 28
	COMMENTS: For best results, apply in 100 to 150 gal water/acre.
D.	METHOXYFENOZIDE
	(Intrepid) 2F	8–16 oz	2–4 oz	4	7
	MODE OF ACTION GROUP NUMBER1: 18
	COMMENTS: Apply at petal fall. Do not apply more than 16 fl oz/acre/application or 64 fl oz/acre/season.
E.	BACILLUS THURINGIENSIS ssp. KURSTAKI#
	(various products)	Label rates	—	4	0
	MODE OF ACTION GROUP NUMBER1: 11
	COMMENTS: Make two applications during bloom: the first between popcorn and the beginning of bloom and the second 7–10 days later, but no later than petal fall. Compatible with fungicide sprays, and can be tank mixed with them. Good coverage is essential. Ground application using a concentrate rate (80–100 gal water maximum) is preferred. If aerial applications must be made because conditions do not permit ground application, a concentrate rate (5 gal or less) is preferred. Fly material on at a height of about 20 ft over the canopy using appropriate nozzles to allow better deposition on the treetops. Precede this treatment with an oil spray during the delayed dormant season to control San Jose scale and European red mite eggs
AFTER BLOOM
A.	SPINETORAM
	(Delegate) WG	4.5–7 oz	1.125–1.75 oz	4	1
	MODE OF ACTION GROUP NUMBER1: 5
B.	SPINOSAD
	(Entrust)#	1.71–2.5 oz	0.43–0.6 oz	4	1
	(Success)	6–8 oz	1.5–2 oz	4	1
	MODE OF ACTION GROUP NUMBER1: 5
	COMMENTS: Most affective when applied at petal fall. This product is toxic to bees for 3 hours following treatment; apply in the 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.
C.	METHOXYFENOZIDE
	(Intrepid) 2F	8–16 oz	2–4 oz	4	7
	MODE OF ACTION GROUP NUMBER1: 18
	COMMENTS: Apply at petal fall. Do not apply more than 16 fl oz/acre/application or 64 fl oz/acre/season.
D.	CHLORANTRANILIPROLE
	(Altacor)	3–4.5 oz	0.75–1.125 oz	4	10
	MODE OF ACTION GROUP NUMBER1: 28
	COMMENTS: For best results, apply in 100 to 150 gal water/acre.
E.	FLUBENDIAMIDE
	(Belt) SC	3–4 oz	0.75–1 oz	12	7
	MODE OF ACTION GROUP NUMBER1: 28
	COMMENTS: This product is reported to be highly toxic to honey bees.
F.	BACILLUS THURINGIENSIS ssp. KURSTAKI#
	(various products)	Label rates	—	4	0
	MODE OF ACTION GROUP NUMBER1: 11
	COMMENTS: 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 feeing. Most effective against yound larvae. Requires more than one treatment; apply second application 7 to 10 days after first.
G.	CARBARYL*
	(Sevin) XLR Plus	3–4 qt	0.75–1 qt	12	1
	MODE OF ACTION GROUP NUMBER1: 1A
	COMMENTS: May cause increased spider mite problems; best used late in the season. Do not apply more than 14 qt/acre/season.
H.	PHOSMET
	(Imidan) 70WP	4.25 lb	1 lb	5 days	14
	MODE OF ACTION GROUP NUMBER1: 1B
**	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 label allows.
*	Permit required from county agricultural commissioner for purchase or use.
+	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.
#	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/.

IMPORTANT LINKS

• Degree-day calculator
• Fruit sampling for pest damage in harvest (115 KB, PDF)

PUBLICATION

UC IPM Pest Management Guidelines: Nectarine
UC ANR Publication 3451
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 Insects and Mites:
R. E. Rice, Kearney Agricultural Center, Parlier

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