Agriculture

Leaf Curl Plum Aphid

  • Brachycaudus helichrysi
Updated: 04/2009

Tools

PestManage: a decision support tool to view and compare pest management options

Description of the Pest

The leaf curl plum aphid is often found inside curled leaves. It is shiny and varies considerably in color from green to brownish green or brownish yellow. This aphid overwinters in the egg stage near the base of buds. In spring it rapidly builds populations on new foliage, causing affected spurs to develop tightly curled leaves. In May, the aphids migrate from the orchard to summer host plants in the family Asteraceae.

Damage

Colonies of this pest cause leaves to curl tightly. Often only one limb or a portion of a limb is infested early in the year. Large amounts of honeydew are secreted by this aphid. Tree growth and fruit sugar content can both be reduced by populations of this aphid.

Management

Several natural enemies are important in the control of aphids in the orchard, but aphid populations often require treatment. The best indicator of populations is orchard history. The best time to treat is during the dormant or delayed dormant period. If aphids are a chronic problem in the orchard, apply a treatment early in dormancy; otherwise, sample during dormancy to determine the need to treat as described below. Spring treatments may also be made. After harvest, a zinc sulfate application will provide zinc to the trees as well as hasten leaf fall. Without the leaves on the tree, the aphid life cycle is disrupted. Zinc sulfate (36%) applied at 10-20 lb/acre can be applied in early to mid-October to help in this process.

Biological Control

There are many natural enemies that feed on leaf curl plum aphid; however, fruit size may still be reduced and curled leaves will not uncurl after aphids are suppressed. The recent introductions of Aphidius colemani has led to substantial levels of parasitism of this aphid. Important predators include: lady beetles, green lacewings, brown lacewings, syrphid flies, and soldier beetles.

Organically Acceptable Methods

Biological control and sprays of narrow range oil or neem oil are organically acceptable methods of controlling this pest.

Monitoring and Treatment Decisions

If aphids are a chronic problem, a treatment in late fall/early dormancy (November 1) is a very effective way to manage these pests and is less likely to create water quality problems caused by pesticide runoff than treatments applied during the rainier season in January and February. If leaves are still on trees at this time, aphids and parasites can be present. Oil treatments are not recommended at this time because they are very damaging to parasite populations and not effective for aphid control.

Dormant monitoring. If the November 1 treatment is not applied, be sure to monitor during dormancy. (For more information, see DORMANT SPUR SAMPLE.) If dormant monitoring indicates treatment is necessary, two applications of oil at bloom can be used in orchards where a dormant/delayed dormant treatment is not required to manage scale problem. Parasites are not active at bloom, and they are not affected by the bloom oil sprays.

Spring monitoring. If aphids have been a problem in the past or if a dormant or delayed dormant application was not applied, monitor leaf curl plum aphid in spring along with mealy plum aphid. Follow the monitoring guidelines in SPRING/SUMMER MONITORING to determine if treatment is necessary.

Pesticides and Natural Enemy Releases

Not all registered pesticides are listed. The following are ranked by their IPM value, with the most effective and least harmful to natural enemies, honey bees, and the environment listed at the top of the table. When choosing a pesticide, consider information related to water and air quality, resistance management, and the pesticide's properties and application timing. Use PestManage to compare summarized management options for different pests in the same crop. Always carefully read the label of the product being used and take all necessary precautions when handling pesticides.

Rank Active ingredient Example trade name Group Group Order MoA 1 Amount to use REI (hours) ‡ PHI (days) ‡ Comments Selectivity 2 Bees 3 Predatory mites 4 Predators 5 Parasitoids 5 Residue duration 6 Leaching(fish) 7 Adsorbed runoff(fish) 8 Solution runoff(fish) 9 Leaching(human) 10 Solution runoff(human) 11 Last updated 12
A
Omni Supreme # Bloom 4

UNM

4 gal 12 — Narrow range oil. Apply in 100 gal water... broad II low low low none to short very low low very low very low very low 06/2025
B
Asana XL Delayed-Dormant 2

3A

3 oz 12 14 Pyrethroid residues remaining on leaves... broad I high moderate high moderate high intermediate extra high low intermediate 06/2025
C
Warrior II Delayed-Dormant 2

3A

0.64–1.28 fl oz 24 14 Residues remaining on leaves and bark ma... broad I high high high moderate intermediate low extra high low high 06/2025
A
Imidan 70-W Delayed-Dormant 2

1B

2.12 lb See label 7 Apply with a buffer to lower solution pH... broad I high high high moderate to long intermediate low high intermediate high 06/2025
B
Diazinon AG500 Dormant 1

1B

1 pt/100 gal 4 days 21 Apply as early as November 1st even thou... broad I low high high moderate to long high high extra high intermediate high 06/2025
C
Asana XL Dormant 1

3A

3 oz 12 14 Apply as early as November 1st even thou... broad I high moderate high moderate high intermediate extra high low intermediate 06/2025
A
Imidan 70-W Dormant 1

1B

2.12 lb See label 7 Apply with a buffer to lower solution pH... broad I high high high moderate to long intermediate low high intermediate high 06/2025
A
Diazinon AG500 Spring 4

1B

1 pt/100 gal 4 days 21 Avoid drift and runoff into surface wate... broad I low high high moderate to long high high extra high intermediate high 06/2025
E
Wrangler Spring 4

4A

See label 12 7 Apply postbloom. Repeat applications of... narrow I — — high short to moderate — — — — — 06/2025
B
Omni Supreme # Spring 4

UNM

6–8 gal 12 — Narrow range oil. Apply in 200 gal water... broad II low low low none to short very low low very low very low very low 06/2025
C
Trilogy # Spring 4

UNE

2% 4 0 Repeat applications may be necessary. broad II low low low short low low intermediate very low low 06/2025
D
Actara Spring 4

4A

3–4 oz 12 14 Highly toxic to bees. Remove (mow, disc,... narrow I — 13 — moderate moderate very low very low low high high 06/2025
B
Omni Supreme # Summer 5

UNM

6–8 gal 12 — Apply in 200 gal water/acre. Narrow rang... broad II low low low none to short very low low very low very low very low 06/2025
A
Trilogy # Summer 5

UNE

2% 4 0 Repeat applications may be necessary. Oi... broad II low low low short low low intermediate very low low 06/2025
—
No information.
I
Do not apply or allow to drift to plants that are flowering including weeds. Do not allow pesticide to contaminate water accessible to bees including puddles.
II
Do not apply or allow to drift to plants that are flowering including weeds, except when the application is made between sunset and midnight if allowed by the pesticide label and regulations. Do not allow pesticide to contaminate water accessible to bees including puddles.
III
No bee precaution, except when required by the pesticide label or regulations.
  • ‡ a b Restricted entry interval (REI) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without personal protective equipment. Preharvest interval (PHI) is the number of days from treatment to harvest. In some cases, the REI exceeds the PHI. The longer of the two intervals is the minimum time that must elapse before harvest.
  • # a b c d e  Acceptable for use on certified organic crops. Check with your certifier to confirm before application.
  • 1 ↩ Group numbers for insecticides and miticides are assigned by the Insecticide Resistance Action Committee (IRAC). Insecticides with unknown modes of action are assigned mode-of-action group numbers (MoAs) that begin with UN. Rotate pesticides 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; insecticides with a 1B group number should be alternated with insecticides that have a group number other than 1B.
  • 2 ↩ Range of insect and mite groups affected by a pesticide. Broad means the pesticide affects most groups of insects and mites; narrow means the pesticide affects only a few specific groups.
  • 3 ↩ Risk of harm to honey bees. For more information, see Bee Precaution Pesticide Ratings.
  • 4 ↩ Risk of harm to predatory mites. Toxicities are generally to western predatory mite, Galendromus occidentalis. Where differences have been measured in toxicity of the pesticide-resistant strain versus the native strain, these are listed as pesticide-resistant strain or native strain.
  • 5 a b Risk of harm to parasitoids and general predators. Toxicities are averages of reported effects and should be used only as a general guide. Actual toxicity of a specific insecticide depends on factors including the application rate, environmental conditions, and the life stage and species of a parasitoid or predator.
  • 6 ↩ Length of time residue affects natural enemies. Short means hours to days; moderate means days to 2 weeks; and long means many weeks or months.
  • 7 ↩ Risk of harm to fish from leaching, based on USDA Natural Resources Conservation Service Windows Pesticide Screening Tool (WIN-PST).
  • 8 ↩ Risk of harm to fish from adsorbed runoff, based on USDA Natural Resources Conservation Service Windows Pesticide Screening Tool (WIN-PST).
  • 9 ↩ Risk of harm to fish from solution runoff, based on USDA Natural Resources Conservation Service Windows Pesticide Screening Tool (WIN-PST).
  • 10 ↩ Risk of harm to humans from leaching, based on USDA Natural Resources Conservation Service Windows Pesticide Screening Tool (WIN-PST).
  • 11 ↩ Risk of harm to humans from solution runoff, based on USDA Natural Resources Conservation Service Windows Pesticide Screening Tool (WIN-PST).
  • 12 ↩ Date information was last updated in the UC IPM Pest Management Guidelines.
  • 13 ↩ May cause an increase in spider mite numbers.

Important Links

UC Peer Reviewed Logo

UC IPM Pest Management Guidelines: Plum
UC ANR Publication 3462

W.J. Bentley (emeritus), UC IPM and Kearney Agricultural Research and Extension Center, Parlier

K.R. Day (emeritus), UC Cooperative Extension Tulare County

Acknowledgement for Contributions to Invertebrates

R.E. Rice, Kearney Agricultural Research and Extension Center, Parlier

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