How to Manage Pests

UC Pest Management Guidelines

DESCRIPTION OF THE PESTS

Katydids resemble grasshoppers but have long antennae. Nymphs are wingless and have black and white banded antennae. Females of the forktailed katydid lay gray, oval, flat eggs in leaves where they have been feeding. Nymphs appear in April and May and take 2 to 3 months to mature. Angularwinged katydids are larger than forktailed katydids, have broader wings and have a humpback appearance both as nymphs and as adults. Females lay their gray, oval eggs in two overlapping rows on twigs and leaves. Katydids have only one generation a year.

DAMAGE

Of the two species feeding on citrus, only the forktailed katydid causes economic damage. This species feeds on young fruit at petal fall with subsequent buildup of scar tissue and distortion of expanding fruit. Katydids take a single bite from a fruit and then move to another feeding site on the same or nearby fruit. In this way, a few katydids can damage a large quantity of fruit in a short time. They also eat holes in leaves and maturing fruit, creating injury that resembles damage by citrus cutworm. The angularwinged katydid is less abundant than the forktailed katydid and feeds only on leaves.

MANAGEMENT

With the reduced use of organophosphate and carbamate insecticides, katydids have become more numerous. Larger instars are not well controlled by cryolite or spinosad.

Biological Control
A number of parasitic wasps will attack katydid eggs, however, they are generally not effective enough to prevent damaging levels from developing.

Organically Acceptable Methods
Biological control and the Entrust formulation of spinosad are organically acceptable methods.

Monitoring and Treatment Decisions
Monitor for katydids starting in April. Before petal fall, they will be feeding on the newly expanding leaf flush. A timed search (3 minutes per tree) of 20 trees can be used to estimate their numbers. Approach the tree slowly, because katydids have excellent eyesight and will hide behind leaves if they see you coming. Look for damaged leaves, and search the foliage around the damaged area for katydids. There is no treatment threshold for katydids; however, if you detect leaf feeding and can find one or more per tree in a timed search then it is probably time to treat.

If treatments of diflubenzuron (Micromite) or cryolite are planned, put them on before petal fall because they are slow acting. Micromite does not kill the katydid until it tries to molt (10 days) and cryolite is a stomach poison that slowly kills the katydid over several days.

After petal fall, katydids can do a lot of damage in a short amount of time, so killing them quickly is important. If they are found at this time, many growers add a low rate of chlorpyrifos or a low rate of a pyrethroid to the citrus thrips spinosad treatment. The reduced rate of the organophosphate or pyrethroid helps to preserve natural enemies needed for other pests.

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.	CRYOLITE
	(Prokil Cryolite) 96	8–20 lb/acre (OC)	12	15
	(Kryocide) 96 WP	8–20 lb/acre (OC)
	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 katydids. Do not exceed 90 lb/acre/season.
B.	DIFLUBENZURON*
	(Micromite) 80 WG	3.125–6.25 oz/acre (OC)	12	21
	RANGE OF ACTIVITY: Pests: intermediate (katydids, peelminer, leafminer, grasshoppers); Natural enemies: predatory beetles
	PERSISTENCE: Pests: intermediate; Natural enemies: intermediate
	MODE OF ACTION GROUP NUMBER1: 15
	COMMENTS: Can be used during bloom. Timing treatments for peaks in moth flights is important because it only kills the egg stage of the peelminer. Apply by ground application using 50-200 gallons of water per acre. Do not apply more than 6.4 oz per 90 day period or 18.75 oz per year. Do not apply within 25 feet of bodies of water. Use allowed under a FIFRA 2(ee) recommendation.
C.	NALED
	(Dibrom) 8E	1–2 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 oranges, grapefruit, lemons, and tangerines. Apply at petal fall. R.E.I. is 2 days for 1 pt or less; 3 days for more than 1 pt.
D.	CHLORPYRIFOS*
	(Lorsban) 4EC	2–8 oz/acre (A)	5 days	see comments
		...or...
		2–8 oz/acre (OC)	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. No more than 2 applications/year with at least 30 days between applications. Do not apply during daylight hours of bloom period. Preharvest interval is 21 days for up to 7 pt/acre and 35 days for over 7 pt/acre.
E.	DIMETHOATE 4	0.5–2 pt/acre (OC)	48	15
	RANGE OF ACTIVITY: Pests: broad (many insects); Natural enemies: most
	PERSISTENCE: Pests: intermediate; Natural enemies: long
	MODE OF ACTION GROUP NUMBER1: 1B
	COMMENTS: For use on oranges, grapefruit, lemons, and tangerines.
F.	CYFLUTHRIN*
	(Baythroid) 2E	6.4 fl oz/acre (OC)	12	0
	RANGE OF ACTIVITY: Pests: broad (many insects); Natural enemies: most
	PERSISTENCE: Pests: intermediate; Natural enemies: intermediate (low rates), long (high rates)
	RESISTANCE: In some citrus thrips populations in the San Joaquin Valley
	MODE OF ACTION GROUP NUMBER1: 3A
	COMMENTS: Only a single application may be made per crop season. To reduce the potential for resistance, make a total of only one pyrethroid application (for all pest species) per year. Do not apply within 25 feet of lakes, reservoirs, rivers, permanent streams, marshes, or natural ponds, estuaries, and commercial fish farm ponds.
G.	FENPROPATHRIN*
	(Danitol) 2.4EC	21.33 fl oz/acre (OC)	24	1
	RANGE OF ACTIVITY: Pests: broad (many insects and mites); Natural enemies: most
	PERSISTENCE: Pests: intermediate; Natural enemies: long
	MODE OF ACTION GROUP NUMBER1: 3A
	COMMENTS: Apply in 50–200 gal water/acre. Use only on citrus trees 3 years or older. To reduce the potential for resistance, make a total of only one pyrethroid application (for all pest species) per year. Do not apply in the vicinity of aquatic areas, and do not apply more than 21.33 fl oz/acre/year.
**	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.
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

• Photos of damage to fruit

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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