How to Manage Pests

UC Pest Management Guidelines

DAMAGE
Fruittree leafrollers can occasionally cause damage in spring by feeding on newly set fruit or on ripening Valencias, navels, or grapefruit. Early in spring, young larvae feed mostly on new growth flushes, often resulting in curled leaf terminals. In situations where most of the new flush is consumed (e.g., weak or drought stressed trees with little flush), larvae will tie leaves to fruit and bore inside; this injury provides entry sites for secondary decay organisms, and fruit will drop within 1 to 2 weeks.

MANAGEMENT
Monitor for fruittree leafroller in spring at the same time as citrus cutworm, but count the two species separately. Natural enemies generally are helpful in reducing this pest, and treatments are rarely necessary.

Biological Control
General predators prey on small larvae, and Trichogramma spp. may parasitize the eggs.

Organically Acceptable Methods
Biological control and sprays of Bacillus thuringiensis are acceptable for use in organically certified crops.

Selectivity
The Bacillus thuringiensis (Bt) insecticides (Dipel, Javelin, Cutlass, and MVPII) are toxic only to caterpillar pests. The stomach poison cryolite is specific to foliage-feeding pests. These insecticides are relatively nontoxic to parasites that attack the caterpillars and beneficial insects and mites that feed on other citrus pests. The broad-spectrum organophosphates (Lorsban) and carbamates (Lannate) kill many of the beneficial insects and mites in citrus groves. Some populations of the beneficial mite, Euseius tularensis, show resistance to chlorpyrifos (Lorsban), so this is the least toxic of the broad-spectrum pesticides.

Monitoring and Treatment Decisions
To monitor fruittree leafroller eggs, establish one or two permanent observation trees per site at five locations per block. Before the middle of March, check twigs and small branches thoroughly in the upper one-third of the tree for gray to brown, flat egg masses.

To monitor caterpillars, search the outer canopy of the south and east side of four trees at each sampling site. Spend about 2 to 5 minutes per tree and count all the live leafroller caterpillars. Carry out this procedure in five locations per block. Record the number of worms per unit time and calculate the average number of larvae per hour search. Caterpillars can also be monitored with an L-shaped 1/4 square meter (20 x 20 inches) PVC pipe counting frame to count the number of infested vs. noninfested terminals. Be sure to open nests and count only nests that contain a live worm. Begin counts once a week when the spring feather-leaf flush appears or the first fruittree leafroller caterpillar is seen. Take one sample from the NE corner of 20 randomly selected trees in a diagonal through the block.

When mature fruit are present and 20% or more of the new flush terminals are infested with a live worm, watch carefully for leaves being attached to mature fruit. The potential for damage to mature fruit is greatest at this point. The 20% threshold corresponds to a time search number of about 400 worms per hour. If worms are close to pupating, increase the threshold, especially if fruit is not present. Most larvae pupate before petal fall and treatments are usually not needed.

Common name				Amount to Use	Minimum Days before Harvest+
(trade name)				(type of coverage)**
A.			BACILLUS THURINGIENSIS ssp. KURSTAKI#
			(various)	Label rates	4 hours
			RANGE OF ACTIVITY: Narrow (caterpillars)
			PERSISTENCE: Short
			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)	15
			(Kryocide) 96 WP	8–20 lb/acre (OC)
			RANGE OF ACTIVITY: Narrow (foliage feeders such as worms, katydids, and Fuller rose beetle)
			PERSISTENCE: Long, unless washed off by rain.
			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)	21
			RANGE OF ACTIVITY: Broad (insects and beneficial mites)
			PERSISTENCE: Intermediate
			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.
D.			CARBARYL*
			(Sevin XLR Plus) 4F	2 qt/acre (OC)	5
			RANGE OF ACTIVITY: Broad (insects and beneficial mites)
			PERSISTENCE: Long
			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)	7
			RANGE OF ACTIVITY: Broad (insects and beneficial mites)
			PERSISTENCE: Intermediate
			COMMENTS: For use on grapefruit, lemons, oranges, tangerines. This material is hazardous to honey bees; do not use during bloom.
F.			METHOMYL*
			(Lannate LV) 2.4	1.5–3 pt/acre	3
			RANGE OF ACTIVITY: Broad (insects and beneficial mites)
			PERSISTENCE: Intermediate
			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 honey bees; do not use during bloom.
G.			CARBARYL*
			(Sevin) 80S	2 lb/acre (OC)	5
			RANGE OF ACTIVITY: Broad (insects and beneficial mites)
			PERSISTENCE: Long
			COMMENTS: For use on all varieties. This material is hazardous to honey bees; do not use during bloom.
**			OC - Outside coverage uses 50–500 gal water/acre.
			A - Aircraft applications 5-20 gal water/acre.
+			Minimum days before harvest takes into account the California restricted entry interval and the federal preharvest interval and lists the longer interval. (See Table 1 Mandatory Intervals Between Application, Reentry and Harvest, and Hazards to Bees.)
*			Permit required from county agricultural commissioner for purchase or use.
#			Acceptable for use on organically grown produce.

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 Co.
P. A. Phillips, UC IPM Program, UC Cooperative Extension, Ventura Co.
C. E. Kallsen, UC Cooperative Extension, Kern Co.
D. R. Haviland, UC Cooperative Extension, Kern Co.
Acknowledgments for contributions to the insect, mite, and snail section:
J. Barcinas, E. S. I., Corona, CA
R. Dunn, Badger Farming Co., 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

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