How to Manage Pests

UC Pest Management Guidelines

DESCRIPTION OF THE PEST

The larva of the orange tortrix is a greenish to straw-colored caterpillar with a straw-colored head and prothoracic shield. The major distinguishing characteristic between orange tortrix and omnivorous leafroller caterpillars is that the small mounds at the base of the bristles on the side and back of the omnivorous leafroller are white, whereas on the orange tortrix they are not.

Orange tortrix larvae feed inside nests spun around plant parts. The larvae pupate in dense cocoons inside the nests and adult moths emerge in 8 days to 3 weeks, depending on temperature. Females moths lay 50 to 150 eggs on smooth surfaces such as stems, fruit, and the upper surface of leaves. In coastal areas, orange tortrix may have more than three generations a year, whereas in intermediate districts it has two or three. It is not a problem in the Central Valley.

DAMAGE

Orange tortrix is primarily a pest on Valencias and navel oranges in southern California. First generation orange tortrix larvae feed on leaves. Second generation larvae appear when the growth is hardening off and move preferentially to young fruit and feed around the button. This feeding causes only superficial scars. Later generations feed among clusters of ripening fruit, eating holes into the rind that allow decay organisms to enter; the fruit usually drops within 1 to 2 weeks.

MANAGEMENT

Orange tortrix is generally managed by monitoring throughout spring and summer and treating when necessary. Use selective (toxic to only a narrow group of insects) insecticides to preserve populations of natural enemies.

Biological Control
Several parasites and predators attack orange tortrix. The most common parasites are two wasps, Apanteles aristoteliae and Exochus sp. These wasps lay their eggs in tortrix larvae and the parasites develop within. Apanteles pupates in a white cocoon outside the dead larvae, whereas Exochus pupates inside the larva and emerges through a round exit hole.

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

Monitoring and Treatment Decisions
While orange tortrix larvae should be monitored throughout spring and summer, the period from May through July is especially important. At 7- to 10-day intervals, look for orange tortrix and evidence of parasitism mainly on the south and east quadrants of trees. If 15 larvae are found per hour of search on oranges and grapefruit, or 30 larvae per hour of search on lemons, a treatment may be warranted, depending on the level of parasitism.

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 all varieties. Do not apply more than twice/fruit year or make applications less than 30 days apart. 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. R.E.I. 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: 1A
	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: long
	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.
#	Acceptable for use on organically grown produce.
*	Permit required from county agricultural commissioner for purchase or use.
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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