How to Manage Pests

UC Pest Management Guidelines

Citrus

Fuller Rose Beetle

Scientific Name: Naupactus (Asynonychus) godmani

(Reviewed 9/08, updated 9/13)

In this Guideline:


Description of the Pest

Adult Fuller rose beetles are brown, flightless snout beetles and are all females that reproduce without mating. They can be distinguished from two other snout beetles that occur in California citrus groves but do not cause damage: viewed from the top the Fuller rose beetle head and bulging eyes are different than the cribrate weevil, which has a teardrop-shaped head with closely spaced eyes, and viewed from the side, the Fuller rose beetle's snout is less sharply pointed to the ground than that of the vegetable weevil.

The Fuller rose beetle has one generation a year. Eggs are laid in a mass of several dozen on fruit, especially underneath the button, or in cracks and crevices in the tree. When eggs hatch, larvae drop to the ground and live in the soil where they feed on roots of citrus for 6 to 10 months. They pupate in the soil and the adults emerge 1.5 to 2 months later.

In the San Joaquin Valley, peak emergence is July through September (very high in August), but adults emerge from the soil year-round (in the San Joaquin Valley, roughly 4.3% emerge in June, 14.5% in July, 53% in August, 17.3% in September, 3.7% in October, 2.6% in November, 2.8% in December, and 1.9% for the combined months of January through May). In southern California, emergence is delayed about a month from that in the San Joaquin Valley and is a bit more spread out with peak months being July through November (very high August through October). Adults are flightless and reach the canopy by climbing up the trunk or branches that touch the ground or vegetation.

Damage

The beetle itself does not generally cause economic damage in citrus but the presence of viable eggs on fruit exported to other countries such as Korea can be a quarantine concern. Since Fuller rose beetle has been found in Japanese citrus groves, it is no longer a concern for fruit exported to Japan.

Fuller rose beetle adults feed along the margins of citrus leaves, creating notches and leaving a characteristic sharp, ragged appearance. Normally, they are not a concern except on topworked trees where the beetles will feed on new buds or if a young tree is planted in a mature grove and beetles concentrate their feeding on the new growth of that tree.

Management

If management of Fuller rose beetles is necessary because it has become a quarantine concern there are two management strategies explained in Monitoring and Treatment Decisions below that incorporate cultural and chemical control methods: season-long local suppression and treatments to prevent egg laying close to harvest.

Biological Control

The internal egg parasite, Fidiobia citri, can parasitize up to 50% of each egg mass. Parasitized eggs are a dark gold color during the parasite's larval stage and a few may persist long after unparasitized eggs have hatched. Once the parasite pupates, the egg appears dark black for several days prior to wasp emergence. While parasites assist with control, they do not reduce Fuller rose beetle numbers enough to enable fruit to be exported to quarantine countries.

Cultural Control

If Fuller rose beetle has been a problem in your orchard in the past, an important component of the strategy to prevent the flightless adults from reaching the canopy is using skirt pruning combined with a trunk barrier. Skirt pruning by itself is about 30% effective in reducing the number of beetles that will produce eggs several weeks after feeding on citrus foliage. Skirt prune trees 24 to 30 inches above the ground and apply a sticky material to the trunk to prevent adults from reaching the canopy. Sticky material can be expected to last 2 to 10 months, depending on wash-off by sprinklers and the amount of dirt and leaf contamination. Sticky material will also control ants, and if it contains tribasic copper sulfate, it is effective against brown garden snail as well.

Some concern has been expressed regarding the application of sticky polybutene materials directly to the trunk of citrus trees, especially if multiple applications are applied to the same area of the trunk. The sticky material can be applied on top of a tree wrap but this is both laborious and expensive. Trials to date on mature trees have failed to show serious phytotoxicity (minor bark cracking has been seen in a very small number of cases) except in situations where damage is associated with sunburn—that is where the banded area is exposed to direct sunlight, as with topworked trees. Young trees have a very thin cambium layer and are more susceptible to damage. On young or topworked trees, apply sticky materials only on top of a tree wrap to protect the tree from sunburn.

Organically Acceptable Methods

Biological and cultural controls, including skirt pruning and the application of sticky materials are acceptable organic methods.

Monitoring and Treatment Decisions
Adult Monitoring

If fruit may be exported to countries prohibiting fruit with unhatched Fuller rose beetle eggs, sample the orchard starting in June. Previous-year damage to foliage low and inside the tree canopy provides past evidence of Fuller rose beetle. Current-year numbers can be monitored from a minimum of 20 trees per 10 acre block by shaking or beating branches to knock adult beetles onto a sheet or tray. The next step is to conduct season-long insecticide suppression to prevent egg laying close to harvest.

Season-Long Local Suppression

The goal is to reduce the population by (1) skirt pruning, (2) ground (soil) or trunk sprays with bifenthrin, and (3) foliar insecticide sprays applied during the period of time when adults might lay eggs that remain viable at harvest. In the San Joaquin Valley, more than 50% of the beetles emerge from the soil in August so that is a key month for control. Apply a ground or trunk bifenthrin spray before peak emergence (June or July). Foliar sprays are more important to apply August through October after peak emergence, because the eggs deposited earlier in the season hatch before harvest. When practicing season-long suppression, follow these guidelines in the San Joaquin Valley (in southern California, a similar strategy should be used but applications should be applied one month later):

  • If three treatments are planned, they should be applied in June (soil), August (foliar) and October (foliar).
  • If two treatments are planned, then apply a ground (soil) or foliar spray in August and a foliar treatment in October.

A substantial reduction in beetle numbers will likely take several years with two to three treatments per year. It is essential to combine skirt pruning with one or more of the other strategies (ground sprays, trunk sprays, foliar insecticide sprays, or a combination of these) to improve effectiveness.

Skirt Pruning and Ground (Soil) or Trunk Sprays

To reduce egg laying on fruit, skirt prune trees to a height of 24 inches or more by late May and apply bifenthrin ground or trunk sprays starting in early June (San Joaquin Valley) or July (southern California). Monitor the orchard every 4 to 6 weeks and remove weeds growing upward or branches and suckers bending downward that beetles can use to access the tree.

Apply bifenthrin to the ground with a weed or other sprayer using low pressure so the spray does not splash on fruit. Cover the entire area under the tree canopy from the trunk to the drip line. Consult the insecticide label for details. Apply trunk sprays with a shielded sprayer or with a home-built U-shaped hand wand.

  • Use low pump pressure so the insecticide does not splash onto the foliage or fruit.
  • Do a test application with water only to determine the amount of solution that is needed per acre for thorough coverage of the soil under the tree (40 gal) or trunk (10 gal) and to make sure the spray does not contact foliage or fruit.
  • Keep the solution thoroughly mixed during application.
Treatments to Prevent Egg Laying Close to Harvest

If skirt pruning and ground or trunk sprays have not been fully effective (adults are laying eggs under the button of the fruit) also apply one or two foliar insecticides during the period 600 degree-days (accumulated above the 51°F lower threshold) before harvest to kill adults that would lay eggs that would be viable at harvest.

Typical degree-days per month above the Fuller rose beetle egg development lower threshold of 51°F. Modified from Morse, J. G. and K. R. Lakin 1987 (A degree-day model for Fuller rose beetle, Citrograph 72(11): O-P).

Month Madera, Madera Co. Orange Cove, Fresno Co. Lindcove*, Tulare Co. Lindsay-Strathmore, Tulare Co. Porterville*, Tulare Co. McFarland, Kern Co. Lamont, Kern Co. Maricopa, Kern Co.
January 22 28 68 52 55 42 52 40
February 93 101 124 126 113 126 135 128
March 184 188 224 219 219 237 233 206
April 310 303 326 335 318 372 365 345
May 517 506 541 528 524 600 610 600
June 707 724 730 708 693 784 811 812
July 876 899 929 882 874 956 1010 984
August 834 843 882 838 827 909 973 938
September 661 688 692 662 660 729 790 764
October 414 429 448 425 421 469 525 515
November 136 156 175 163 158 168 184 173
December 19 33 66 50 54 39 52 44
Yearly total 4,772 4,899 5,205 4,989 4,915 5,429 5,739 5,546

 

Month Santa Paula, Ventura Co. Ojai, Ventura Co. Riverside, Riverside Co. Indio, Riverside Co. Niland, Imperial Co. Valley Center, San Diego Co.
January 197 170 170 236 219 229
February 193 176 186 307 270 209
March 235 219 239 470 396 297
April 294 292 340 659 545 373
May 348 376 474 876 782 460
June 425 496 634 1117 1015 537
July 541 654 813 1291 1224 663
August 555 677 832 1269 1222 740
September 509 581 708 1058 1028 661
October 411 440 512 789 724 500
November 269 265 278 394 361 315
December 202 180 182 241 211 200
Yearly total 4,178 4,524 5,367 8,706 7,994 5,183
 
Weather data were obtained from UC IPM Online (UC Statewide IPM Program) at http://www.ipm.ucdavis.edu/WEATHER/index.html. The above data are EXPECTED degree-days each month of the year for the indicated location based on average weather data over the past 30 years.
*for Lindcove and Porterville, data were based on average weather data for two nearby weather stations for a total of 25 and 29 years respectively.

With this treatment strategy, only unhatched eggs (eggs deposited before the 600 degree-days point in time) are present at harvest. For example, if harvest was at the end of January, insecticide applications to prevent adults from laying eggs that would be viable at that time would need to start in early to mid-November in Riverside and Ventura counties, and in early October in Kern and Tulare counties. The eggs laid prior to these treatments would have 600 degree-days to complete their development and hatch before harvest.

Examine eggs on fruit to determine if these treatments were successful in eliminating the presence of unhatched eggs.

Egg Monitoring

Just before harvest, sample fruit for egg masses, especially in the areas where adults were found during branch shaking or feeding damage was observed. Sample a minimum of 500 fruit in a 10 acre block (5 fruit per tree from 10 trees per acre).

  1. Select fruit at chest height from a different quadrant of the canopy.
  2. Clip the stem 2 inches from the fruit, then hold the stem and twist off the button.
  3. Look for egg masses on the underside of the button and on the fruit where it was covered by the button.

For fruit to be shipped to a country that requires fruit free of unhatched Fuller rose beetle eggs, infestation levels should be less than one fruit infested with a viable, unhatched egg per 500 fruit sampled at harvest.

Common name Amount to use R.E.I.‡ P.H.I.‡
(example trade name) (type of coverage)** (hours) (days)

  Calculate impact of pesticide on air quality
 
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 the label of the product being used.
 
TRUNK TREATMENTS USED WITH SKIRT PRUNING
 
A. STICKY POLYBUTENE MATERIALS# 2- to 4-inch band NA NA
  RANGE OF ACTIVITY: Pests: narrow (trunk climbers); Natural enemies: few, if any
  PERSISTENCE: Pests: long; Natural enemies: long
  COMMENTS: For use on all varieties. Use polybutene-based products only. Do not apply sticky materials directly on the trunk of young or top worked trees where the treated area is exposed to the sun—in these cases, use a 6- to 18-inch wrap under the sticky material to protect the tree from sunburn. Exercise caution in applying multiple applications (more than 3 or 4)—watch for symptoms of bark cracking. Apply the sticky band high enough to avoid sprinklers, dust, and direct sunlight. Reactivate periodically by rubbing with a stick to remove dust. Check to ensure that hanging branches, sticks, weeds, etc. are not allowing Fuller rose beetles access to trees.
 
B. BIFENTHRIN*
  (Brigade WSB) 18 inch band
2.55.0 lb/acre
12 1
  RANGE OF ACTIVITY: Pests: narrow (insects on trunk); Natural enemies: few, if any
  PERSISTENCE: Pests: long; Natural enemies: long
  MODE OF ACTION GROUP NUMBER1: 3
  COMMENTS: Do not allow the insecticide to contact fruit or foliage. Under a 24(c) Special Local Needs (SLN) label, two treatments of 5 lb (0.5 lb a.i.)/acre, applied 12 to 16 weeks apart, or four treatments of 2.5 lb (0.25 lb a.i.)/acre, applied 6 to 8 weeks apart, are allowed per year. Applications can be made either with a hand wand sprayer or a shielded sprayer. The SLN label expires September 20, 2018. Additional information may be found at California Citrus Quality Council (CCQC) advisory. Bifenthrin is both toxic and repellent to adult Fuller rose beetles.
 
FOLIAR SPRAYS FOR ADULT BEETLES
 
A. CRYOLITE
  (Prokil Cryolite 96) 20 lb/acre (IC) 12 15
  (Kryocide) 20 lb/acre (IC) 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: unknown
  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 Fuller rose beetles. There is no cryolite maximum residue limit (MRL) for Korea.
 
B. CARBARYL*
  (Sevin XLR Plus) 1 qt/100 gal in 250–750 gal 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. The 5 day PHI is based on a U.S. tolerance of 10 ppm (7 ppm MRL in Japan). The MRL for Korea is 0.5 ppm so a 5 day PHI will likely not meet MRLs in Korea.
 
C. THIAMETHOXAM*
  (Actara) 5.5 oz in 250–500 gal 12 0
  RANGE OF ACTIVITY: Pests: broad (many insects); Natural enemies: most
  PERSISTENCE: Pests: long; Natural enemies: long
  MODE OF ACTION GROUP NUMBER1: 4A
  COMMENTS: For use on all varieties. The minimum interval between applications is 7 days. The 0 day PHI is based on a U.S. tolerance of 0.4 ppm (Korean and Japanese MRLs are 1.0 ppm).
 
** IC - Intermediate coverage uses 250–600 gal/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.
NA Not applicable.
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). For additional information, see their Web site at http://www.irac-online.org/.
* Permit required from county agricultural commissioner for purchase or use.

IMPORTANT LINKS

[Precautions]

PUBLICATION

[UC Peer Reviewed]

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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