How to Manage Pests

UC Pest Management Guidelines

Citrus

Glassy-Winged Sharpshooter

Scientific Name: Homalodisca vitripennis

(Reviewed 2/17, updated 2/17)

In this Guideline:


Description of the Pest

Glassy-winged sharpshooter is in the same insect family as leafhoppers (Cicadellidae). Glassy-winged sharpshooter was introduced into Southern California in the late 1980s. Its current distribution in agricultural areas is Southern California and Kern, Tulare, and Fresno counties. The glassy-winged sharpshooter continues to spread slowly northward in the Central Valley. Infestations that have appeared in various other counties in Central and Northern California have been eradicated or suppressed.

The glassy-winged sharpshooter is a large insect compared to other leafhoppers. Adults are about 0.5 inch long and are generally dark brown to black when viewed from the top or side. The abdomen is whitish or yellow. The head is brown to black and covered with numerous ivory to yellowish spots. These spots are helpful in distinguishing glassy-winged sharpshooters from smoke-tree sharpshooters, which have light-colored wavy lines on the head.

Females lay their eggs in masses of about 5 to 15 in the lower leaf surface of young, fully developed leaves. When it is first laid, the egg mass appears as a greenish blister on the leaf. The female covers the leaf blister with a secretion that resembles white chalk and is more visible than the leaf blister. Nymphs hatch in 10 to 14 days and proceed to feed on the leaf petioles or small stems.

The glassy-winged sharpshooter has two generations per year in California. In late winter and early spring, adults become active. Citrus is an especially attractive egg-laying host during late March through April and again in late June through August. The first generation of glassy-winged sharpshooter become adults by mid-June, and the number of young adults continues to increase through July and August. Glassy-winged sharpshooter will overwinter in citrus as well as weeds, ornamentals, and various trees (e.g., Eucalyptus windbreaks).

Damage

The glassy-winged sharpshooter feeds, reproduces, and is often abundant on a variety of host plants including agricultural crops (citrus and grapes) and a large number of ornamental plants. The insect feeds on the nutrient-poor xylem of the plant and must consume copious amounts of fluid in order to gain enough nutrition to grow and reproduce. Consequently, the adults and nymphs excrete large amounts of liquid while feeding, which gives the fruit and foliage a whitewashed appearance.

Extremely high numbers of glassy-winged sharpshooter have been shown to reduce fruit quality and yield of coastal lemons and Valencia oranges in Southern California. In recent years, however, very high numbers are rarely seen in Southern California—likely because of increased parasite activity. Currently, insecticides are applied primarily to reduce sharpshooter populations that might move to grapes or to disinfest citrus trees before harvest. In Kern County, warm winters that allow increased survival and pesticide resistance have resulted in increasing populations of sharpshooters that have become more difficult to control.

The glassy-winged sharpshooter is a serious pest of grapes because it acts as a vector of the strain of Xylella fastidiosa that causes Pierce's disease in vineyards. It also vectors the strain that causes oleander leaf scorch in oleander. The bacteria multiply and block the water-conducting system of the plant causing water stress and eventual plant death. There is no known cure for the disease. Because many glassy-winged sharpshooters overwinter in citrus, citrus acts as a source of sharpshooters for neighboring vineyards. Glassy-winged sharpshooter has been reported as a vector of the Xylella fastidiosa strain of bacteria that causes citrus variegated chlorosis; however, this disease has not yet been found in the U.S.

Management

To protect vineyards in uninfested areas of the state, quarantine regulations are in effect to slow the spread of glassy-winged sharpshooter from Southern California and parts of Kern, Tulare, and Fresno counties northward. Citrus orchards in glassy-winged sharpshooter-infested areas must be disinfested of glassy-winged sharpshooter before citrus fruit can be harvested and shipped to uninfested regions. Nursery citrus trees must have a pesticide applied before they can be shipped to uninfested areas. In infested areas of the state, citrus orchards with significant yellow sticky card trap catches of glassy-winged sharpshooters have pesticides applied to bring the overall numbers down and reduce the threat of sharpshooters in nearby vineyards. Although biological control agents are being released in urban areas, current management primarily involves insecticide applications because of the threat of Xylella to the grape industry.

Biological Control

Biological control is an organically acceptable method of reducing sharpshooter numbers; however, at this time, it may not provide sufficient reduction of glassy-winged sharpshooter numberss for areawide suppression programs. The egg parasitic wasp, Gonatocerus ashmeadi, is commonly found wherever glassy-winged sharpshooter occurs in California. In the southern and coastal areas of California a closely related species, Gonatocerus walkerjonesi, can be a very effective parasite in the late summer, when the second generation of eggs are deposited. Parasitized glassy-winged sharpshooter eggs are easily recognized by a tiny, round hole at one end of the egg through which the adult parasite emerged. Neither G. ashmeadi nor G. walkerjonesi, however, are normally present at high levels during the first generation of glassy-winged sharpshooter egg laying.

Organically Acceptable Methods

Use biological control to reduce glassy-winged sharpshooter numbers in an organically certified crop. Pyganic plus oil sprays can also suppress sharpshooter numbers.

Selectivity

Pyrethrins are selective because they are extremely short-lived but they are limited in their efficacy. Systemic imidacloprid (Admire) is the next most selective insecticide because it only affects predatory beetles. The foliar neonicotinoids, pyrethroids, and methomyl are highly toxic to most natural enemies. Cyantraniliporole(Exirel) is highly selective, allowing natural enemies to survive. Flupyradifurone (Sivanto) affects only parasitic wasps.

Resistance

Populations of glassy-winged sharpshooter in Kern County are resistant to neonicotinoid (imidacloprid, thiamethoxam) insecticides.

Monitoring and Treatment Decisions

Glassy-winged sharpshooter insecticide applications are only recommended in citrus for one of two reasons: to suppress glassy-winged sharpshooters in the orchard in order toreduce the risk to neighboring grape vineyards or to disinfest fruit just before harvest to limit human-assisted spread of the insect. Different insecticides are recommended for each purpose. Insecticide applications should be avoided where possible because of their potential for disrupting biological control of citrus pests.

Glassy-winged Sharpshooter Suppression

An insecticide application in citrus may be needed to reduce overall numbers so that there are fewer glassy-winged sharpshooters to vector Xylella in neighboring grapes. The glassy-winged sharpshooter suppression program uses yellow sticky cards to monitor infestations and growers are encouraged to make an insecticide application when significant numbers are found in a region.

Pest Control Advisor (PCA) Monitoring

When the weather is cool (winter, early spring), glassy-winged sharpshooter is best monitored in citrus by beating branches of 20 citrus trees per 10-acre block and counting the number of glassy-winged sharpshooter adults and nymphs that fall onto the sheet. An average of more than one per tree is considered a potential threat to neighboring vineyards. During the warmer weather, especially when egg masses are present during April and June through August, it is easier to conduct a timed search. During a 3 to 5 minute examination of each of 20 trees per 10-acre block, count the number of nymphs, adults, and live egg masses observed. Infestations of more than one mobile stage (nymph or adult) and more than one egg mass per tree are considered significant.

Disinfestation of Trees Just Before Harvest

The other reason for insecticide control of glassy-winged sharpshooters in citrus is to disinfest trees immediately before harvest so that fruit can be shipped from a generally infested region (such as Southern California or Kern County) to an uninfested area for packing. To detect mobile stages of glassy-winged sharpshooter, stuff citrus foliage into a sweep net, shake vigorously, and inspect the contents of the net. If any live, mobile glassy-winged sharpshooter stages are found, a pesticide application is needed. The application should be as close to harvest as the preharvest interval and restricted entry interval allow (these intervals are noted in the treatment table below as the PHI and REI respectively). Glassy-winged sharpshooter is a very mobile pest and can rapidly move into the treated orchard from untreated areas as soon as insecticide residues begin to break down.

Common name Amount to use REI‡ PHI‡
(Example trade name) (type of coverage)** (hours) (days)
Calculate impact of pesticide on air quality
Bee precaution pesticide ratings
The following are ranked with the pesticides having the greatest IPM value listed first—the most effective and least harmful to natural enemies, honey bees, and the environment are at the top of the table. When choosing a pesticide, consider information relating to air and water quality, resistance management, and the pesticide's properties and application timing. Not all registered pesticides are listed. Always read the label of the product being used.
 
FOLIAR SPRAYS
 
A. IMIDACLOPRID
  (Admire Pro, soil application) 7–14 fl oz/acre 12 0
  RANGE OF ACTIVITY: Pests: narrow (aphids, glassy-winged sharpshooters, Asian citrus psyllid, citrus leafminer, weevils, whiteflies); Natural enemies: predatory beetles and parasites
  PERSISTENCE: Pests: long; Natural enemies: intermediate
  RESISTANCE: Some glassy-winged sharpshooter populations in Kern County.
  MODE-OF-ACTION GROUP NUMBER1: 4A
  COMMENTS: Apply to soil; remains effective 4 to 5 months. Moderately effective against nymphs and adults. Requires 3 to 4 weeks for uptake into mature citrus to begin to kill the sharpshooter nymphs and adults; does not kill eggs. Lightly pre-wet soil for several hours before application to break soil surface tension. For optimum uptake, apply to newly planted trees or trees irrigated by drip, microsprinkler, or low-pressure irrigation systems. Emitters must provide even, uniform distribution of water. Once the irrigation system reaches operating pressure, inject the insecticide into the system over a calculated time interval (generally 2 hours) to allow uniform distribution throughout the system. The use of a dye marker in the insecticide solution is recommended to determine when lines are clear of the insecticide. Once the solution has cleared all irrigation lines and emitters, continue irrigation to move the insecticide into the active root zone but do not overirrigate or cause runoff. Wait 24 hours before subsequent irrigations. Apply in citrus orchards just before bloom (March) or after petal fall (May–July). Repeat applications of any neonicotinoid insecticide (acetamiprid-Assail; imidacloprid-Admire) can lead to resistance to all neonicotinoids. Alternate neonicotinoids with an insecticide that has a different mode of action to help delay the development of resistance. Highly toxic to bees; do not spray directly or allow to drift onto blooming crops or weeds where bees are foraging.
 
B. BETA-CYFLUTHRIN
  (Baythroid XL)* 1.6–3.2 fl oz/acre in 100–200 gal (OC) 12 0
  RANGE OF ACTIVITY: Pests: broad (many insects); Natural enemies: most
  PERSISTENCE: Pests: intermediate; Natural enemies: intermediate (low rates), long (high rates)
  MODE-OF-ACTION GROUP NUMBER1: 3A
  COMMENTS: Insecticides applied for citrus thrips will help to reduce glassy-winged sharpshooter nymphs and adults. If pyrethroids (e.g., cyfluthrin, fenpropathrin) are used to treat glassy-winged sharpshooters during the months when citrus thrips are present (generally March to October), they can select for citrus thrips resistance. Therefore, it is recommended that the total number of applications of any pyrethroid on citrus (for all pest species) be limited to a single application per season. Highly toxic to bees; do not spray directly or allow to drift onto blooming crops or weeds where bees are foraging.
 
C. FENPROPATHRIN*
  (Danitol 2.4EC) 21.33 fl oz/acre in 100–200 gal (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 to 200 gal water/acre. Use only on citrus trees 3 years or older. Effective at killing nymphs and adults, but residues last for only 2 to 4 weeks. If pyrethroids (e.g., cyfluthrin, fenpropathrin) are used to treat glassy-winged sharpshooters during the months when citrus thrips are present (generally March to October), they can select for citrus thrips resistance. Therefore, it is recommended that the total number of applications of any pyrethroid on citrus (for all pest species) be limited to a single application per season. Do not apply in the vicinity of aquatic areas. Highly toxic to bees; do not spray directly or allow to drift onto blooming crops or weeds where bees are foraging.
 
D. ACETAMIPRID
  (Assail 70WP) 1.7–2.9 oz/acre in 100–200 gal (OC) 12 7
  RANGE OF ACTIVITY: Pests: broad (many insects); Natural enemies: most
  PERSISTENCE: Pests: intermediate; Natural enemies: intermediate
  MODE-OF-ACTION GROUP NUMBER1: 4A
  COMMENTS: Effective in killing nymphs and adults as well as preventing nymphs from emerging from egg masses. Residues last for 4 to 6 weeks. Toxic to bees exposed to direct spray; apply only during late evening, night, or early morning. Apply in a minimum flushed spray of 100 gal/acre by ground. Repeat applications of any neonicotinoid insecticide (acetamiprid-Assail; imidacloprid-Admire) can lead to resistance to all neonicotinoids. Alternate neonicotinoids with an insecticide that has a different mode of action to help delay the development of resistance. Toxic to bees; do not spray directly or allow to drift onto blooming crops or weeds where bees are foraging.
 
E. THIAMETHOXAM
  (Actara) 4–5.5 oz/acre in 100–200 gal (OC) 12 0
  RANGE OF ACTIVITY: Pests: broad (many insects); Natural enemies: most
  PERSISTENCE: Pests: intermediate; Natural enemies: long
  RESISTANCE: Some glassy-winged sharpshooter populations
  MODE-OF-ACTION GROUP NUMBER1: 4A
  COMMENTS: Apply in a minimum flushed spray of 100 gal/acre by ground. Repeat applications of any neonicotinoid insecticide (e.g., acetamiprid [Assail]; imidacloprid [Admire]) can lead to resistance to all neonicotinoids. Alternate neonicotinoids with an insecticide that has a different mode of action to help delay the development of resistance. Toxic to bees; do not spray directly or allow to drift onto blooming crops or weeds where bees are foraging.
 
F. FLUPYRADIFURONE
  (Sivanto 200SL) 10.5–14 fl oz/acre (OC) 12 1
  RANGE OF ACTIVITY: Pests: sucking insects such as psyllids, soft scales and aphids; Natural enemies: parasitic wasps
  PERSISTENCE: Pests: short; Natural enemies: short
  MODE-OF-ACTION GROUP NUMBER1: 4D
  COMMENTS: Safe for bees, and can be used during bloom. Do not exceed 28 fl oz Sivanto (0.365 lb a.i. flupyradifurone)/acre per year. Apply by air in a minimum of 10 gallons/acre.
 
G. CYANTRANILIPROLE
  (Exirel) 13.5-20.5 fl oz/acre (OC) 12 1
  RANGE OF ACTIVITY: Pests: psyllids, sharpshooters, leafminer, aphids; Natural enemies: none
  PERSISTENCE: Pests: intermediate; Natural enemies: none
  MODE-OF-ACTION GROUP NUMBER1: 28
  ...PLUS...
  415 NARROW RANGE OIL 0.25–1.0% See label See label
  RANGE OF ACTIVITY: Pests: broad (unprotected stages of insects and mites); Natural enemies: most
  PERSISTENCE: Pests: short; Natural enemies: short
  MODE OF ACTION: Contact including smothering and barrier effects; also improves translaminar movement and insecticide persistence.
  COMMENTS: Do not make ground applications within 25 feet or air applications within 50 feet of water bodies. Do not exceed 61 oz of Exirel 200 SL or 0.4 lb a.i./acre of cyantraniliprole-containing products/acre per year. Apply by air in a minimum of 10 gallons/acre. Toxic to bees; do not spray directly or allow to drift onto blooming crops or weeds where bees are foraging.
 
ORGANIC
 
A. PYRETHRIN#
  (Pyganic EC5.0II) 4.5–17 fl oz/acre 12 0
  (Pyganic EC1.4) 16–64 fl oz/acre in 100–200 gal (OC) 12 0
  RANGE OF ACTIVITY: Pests: broad (many insects); Natural enemies: most
  PERSISTENCE: Pests: short; Natural enemies: short
  MODE-OF-ACTION GROUP NUMBER1: 3A
  COMMENTS: Short residual, requires repeated applications every 10 to 14 days. Buffering the final spay solution to a pH of 5.5–7.0 is important for efficacy. Pyrethrins degrade rapidly in sunlight. Pyrethrins are only suppressive of glassy-winged sharpshooter, thus frequent applications are needed.
  ...PLUS...
  415 NARROW RANGE OIL# 0.5–1.0% See label See label
  RANGE OF ACTIVITY: Pests: broad (unprotected stages of insects and mites); Natural enemies: most
  PERSISTENCE: Pests: short; Natural enemies: short
  MODE OF ACTION: Contact including smothering and barrier effects; also improves translaminar movement and insecticide persistence.
  COMMENTS: Check with certifier to determine which products are organically acceptable.
 
PREHARVEST DISINFESTATION
 
A. METHOMYL*
  (Lannate LV) 1.5–3 pt/acre in 100–200 gal (OC) 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: Will kill nymphs and adults but not eggs. Short residual. Effectiveness of the pesticide application is reduced if neighboring blocks are untreated and adults fly in. International maximum residue limits of 1 ppm have been established for citrus fruit. Highly toxic to bees; do not spray directly or allow to drift onto blooming crops or weeds where bees are foraging.
 
B. BETA-CYFLUTHRIN
  (Baythroid XL)* 1.6–3.2 fl oz/acre in 100–200 gal (OC) 12 0
  RANGE OF ACTIVITY: Pests: broad (many insects); Natural enemies: most
  PERSISTENCE: Pests: intermediate; Natural enemies: intermediate (low rates), long (high rates)
  MODE-OF-ACTION GROUP NUMBER1: 3A
  COMMENTS: International maximum residue limits have not been established for Taiwan, Hong Kong, China, Malaysia, and Australia. If pyrethroids (e.g., cyfluthrin, fenpropathrin) are used to treat glassy-winged sharpshooters during the months when citrus thrips are present (generally March to October), they can select for citrus thrips resistance. Therefore, it is recommended that the total number of applications of any pyrethroid on citrus (for all pest species) be limited to a single application per season. Highly toxic to bees; do not spray directly or allow to drift onto blooming crops or weeds where bees are foraging.
 
** OC - Outside coverage uses 100 to 250 gal water/acre.
Restricted entry interval (REI) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Preharvest interval (PHI) 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 (un = unknown or uncertain mode of action) are assigned by IRAC (Insecticide Resistance Action Committee).

[Precautions]

PUBLICATION

[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Citrus
UC ANR Publication 3441

Insects, Mites, and Snails

E. E. Grafton-Cardwell, Lindcove Research and Extension Center, Exeter and Entomology, UC Riverside
J. G. Morse, Entomology, UC Riverside
D. R. Haviland, UC Cooperative Extension, Kern County and UC IPM Program
B. A. Faber, UC Cooperative Extension, Santa Barbara and Ventura counties

Acknowledgments for contributions to Insect, Mite, and Snails:
J. Barcinas, E.S.I., Corona, CA
R. Dunn, Badger Farming Co., Exeter, CA
J. Gorden, Pest Management Associates, Exeter, CA
C. E. Kallsen, UC Cooperative Extension, Kern County
D. Machlitt, Consulting Entomology Services, Moorpark, CA
C. Musgrove, retired entomologist, Riverside, CA
K. Olsen, S & J Ranch, Pinedale, CA
N. V. O'Connell, UC Cooperative Extension, Tulare County
P. A. Phillips, UC IPM Program, UC Cooperative Extension, Ventura County
T. Roberts, E.S.I., Corona, CA
T. Shea, UC Cooperative Extension, Riverside County
J. Stewart, Pest Management Associates, Exeter, CA
P. Washburn, Washburn & Sons Citrus Pest Control, Riverside, CA

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