How to Manage Pests

UC Pest Management Guidelines

DESCRIPTION OF THE PEST

The larva of the omnivorous leafroller resembles other tortricid caterpillars, especially the orange tortrix, but it has white tubercles at the base of the bristles on its sides and back. Early instars have a black head and prothoracic shield; later instars have a light brown head and prothoracic shield. The larvae roll and tie leaves together or to fruit with silken threads. When mature they pupate inside the rolled leaves within a cocoon. Adult female moths lay overlapping eggs in clusters that resemble fish scales on the upper surface of leaves and on fruit. There are five to six generations a year, depending on temperatures.

DAMAGE

Omnivorous leafroller is only rarely a pest of citrus in the San Joaquin Valley and in interior and intermediate districts of southern California. In spring, small larvae spin webs and feed on new foliage. Later in the season they tie leaves to fruit and feed under the buttons, leaving ring scarring similar to that of citrus thrips. In summer and fall, they tie leaves to ripening fruit and feed on the rind.

MANAGEMENT

Omnivorous leafroller is generally managed when monitoring for other pests from spring though fall indicates a treatment is necessary. Use selective (toxic to only a narrow group of insects) insecticides to preserve populations of natural enemies.

Biological Control
Several parasites attack the larva of the omnivorous leafroller. The most common are a tachinid fly ,Erynnia tortricis, and an eulophid wasp, Elachertus proteoteratis. Trichogramma spp. attack the eggs.

Organically Acceptable Methods
Biological control and sprays of Bacillus thuringiensis are acceptable for use on organically managed citrus.

Monitoring and Treatment Decisions
If it appears that omnivorous leafroller is present in the grove, monitor in the south and east quadrants of trees. In spring, look for small larvae under sepals when you monitor for citrus thrips. During summer, less frequent monitoring may be sufficient but check to see if parasites are effective. A higher number of larvae can be tolerated in spring, when they feed on young leaves, than in fall, when they are more likely to damage ripening fruit. Keeping this qualification in mind, a control action threshold of about 30 larvae per hour of search can be used.

Common name		Amount to Use	R.E.I.+	P.H.I.+
(trade name)		(type of coverage)**	(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 label of product being used.
A.	BACILLUS THURINGIENSIS ssp. KURSTAKI#
	(various)	Label rate (OC)	4	0
	RANGE OF ACTIVITY: Pests: narrow (caterpillars); Natural enemies: none
	PERSISTENCE: Pests: short; Natural enemies: none
	MODE OF ACTION GROUP NUMBER1: 11.B2
	COMMENTS: Can be used during bloom. Timing is important because of short residual period. Apply only during warm weather to control young, actively feeding worms. Use reduced wind velocity and drive 3 mph.
B.	CRYOLITE
	(Prokil Cryolite) 96	8–20 lb/acre (OC)	12	15
	(Kryocide) 96 WP	8–20 lb/acre (OC)	12	15
	RANGE OF ACTIVITY: Pests: intermediate (foliage feeders such as worms, katydids, and Fuller rose beetle); Natural enemies: few, if any
	PERSISTENCE: Pests: long, unless washed off by rain; Natural enemies: none to short
	MODE OF ACTION GROUP NUMBER1: 9A
	COMMENTS: Check label for variety. Use higher rate for larger trees. Slow-acting stomach poison that may take several days of warm weather to kill worms. Use reduced wind velocity and a speed of 3 mph. Do not exceed 90 lb/acre/season.
C.	CHLORPYRIFOS*
	(Lorsban) 4E	1–2 qt/acre (OC or A)	5 days	see comments
	RANGE OF ACTIVITY: Pests: broad (many insects); Natural enemies: most
	PERSISTENCE: Pests: short (low rates), intermediate (high rates); Natural enemies: short (low rates), intermediate (high rates)
	MODE OF ACTION GROUP NUMBER1: 1B
	COMMENTS: For use on grapefruit, oranges. During the bloom period, apply from 1 hour after sunset until 2 hours before sunrise. Preharvest interval is 21 days for up to 7 pt/acre and 35 days for over 7 pt/acre.
D.	CARBARYL*
	(Sevin) XLR Plus	2 qt/acre (OC)	12	5
	RANGE OF ACTIVITY: Pests: broad (many insects); Natural enemies: most
	PERSISTENCE: Pests: long; Natural enemies: long
	MODE OF ACTION GROUP NUMBER1: 1A
	COMMENTS: For use on all varieties. During the bloom period, apply from 1 hour after sunset until 2 hours before sunrise. XLR Plus formulation is less toxic to honey bees than the 80S formulation when direct application to bees is avoided, and the spray residues have dried. Check with your local county agricultural commissioner regarding application restrictions during the bloom period.
E.	NALED
	(Dibrom) 8E	2 pt/acre (OC)	see comments	7
	RANGE OF ACTIVITY: Pests: broad (many insects); Natural enemies: most
	PERSISTENCE: Pests: short; Natural enemies: intermediate
	MODE OF ACTION GROUP NUMBER1: 1B
	COMMENTS: For use on grapefruit, lemons, oranges, tangerines. This material is hazardous to bees. Do not apply during bloom. Restricted entry interval is 2 days for 1 pt or less; 3 days for more than 1 pt.
F.	METHOMYL*
	(Lannate LV) 2.4	1.5–3 pt/acre (OC or A)	3 days	1
	RANGE OF ACTIVITY: Pests: broad (many insects); Natural enemies: most
	PERSISTENCE: Pests: short; Natural enemies: intermediate
	MODE OF ACTION GROUP NUMBER1: 1B
	COMMENTS: For use on grapefruit, lemons, oranges, tangerines, and tangelos. Apply as needed, except during daylight hours of the bloom period. This material is hazardous to bees. Do not apply during bloom.
G.	CARBARYL*
	(Sevin) 80S	2.5 lb/acre (OC)	12	5
	RANGE OF ACTIVITY: Pests: broad (many insects); Natural enemies: most
	PERSISTENCE: Pests: long; Natural enemies: none
	MODE OF ACTION GROUP NUMBER1: 1A
	COMMENTS: For use on all varieties. This material is hazardous to bees. Do not apply during bloom.
**	A - Aircraft applications 5-20 gal water/acre.
	OC - Outside coverage uses 100–250 gal water/acre.
+	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.
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: Citrus
UC ANR Publication 3441
Insects, Mites, and Snails
E. E. Grafton-Cardwell, Kearney Agricultural Center, Parlier
J. G. Morse, Entomology, UC Riverside
N. V. O‘Connell, UC Cooperative Extension, Tulare County
P. A. Phillips, UC IPM Program, UC Cooperative Extension, Ventura County
C. E. Kallsen, UC Cooperative Extension, Kern County
D. R. Haviland, UC Cooperative Extension, Kern County
Acknowledgments for contributions to Insect, Mites, and Snails:
J. Barcinas, E. S. I., Corona, CA
R. Dunn, Badger Farming County, Exeter, CA
J. Gorden, Pest Management Associates, Exeter, CA
H. Griffiths, E. S. I., Corona, CA
D. Machlitt, Consulting Entomology Services, Moorpark, CA
C. Musgrove, retired entomologist, Riverside, CA
K. Olsen, S & J Ranch, Pinedale, CA
T. Roberts, E. S. I., Corona, CA
J. Stewart, Pest Management Associates, Exeter, CA
P. Washburn, Washburn & Sons Citrus Pest Control, Riverside, CA
K. Godfrey, USDA Biological Control, Sacramento
D. Headrick, California Polytechnic State University, San Luis Obispo
B. Faber, UC Cooperative Extension, Ventura County
J. Kabashima, UC Cooperative Extension, South Coast Research and Extension Center

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