How to Manage Pests

UC Pest Management Guidelines

Pecan

Black Pecan Aphid

Scientific name: Melanocallis caryaefoliae

(Reviewed 12/15, updated 12/15)

In this Guideline:


DESCRIPTION OF THE PEST

The black pecan aphid is the only black colored aphid that attacks pecan foliage.

  • The adult may be various shades of green or black.
  • Nymphs tend to be lighter in color than the adults, especially in spring when instars one through four have little dark pigment.
  • Antennae are pale yellow with small amounts of black on several segments.
  • Eyes are dark red and cornicles are short. In the other two aphid species present on pecan, cornicles are absent or greatly reduced.

Black pecan aphids have multiple generations each year, beginning development in March and continuing into November. Numbers generally peak in fall.

DAMAGE

Black pecan aphid feeding causes bright yellow, angular, 0.4 square inch spots to develop on the leaves between the veins. The spots die and turn brown, and just a few such spots cause a leaflet to shed. Premature leaf drop results in poor nut quality and reduced bloom in subsequent seasons.

MANAGEMENT

Begin scouting for black pecan aphids and their feeding damage in late summer. Continue scouting every 4 to 5 days through the end of the season.

Look at both the bottom and top surfaces of 5 compound leaves on at least 10 random trees throughout the orchard for a total sample of at least 50 compound leaves.

Usually control is not needed until late in the season (after mid-July). At that time, apply a pesticide if levels exceed an average of one black pecan aphid per compound leaf. Note that this threshold was developed in Texas and has not been proven in California.

Soil applied imidacloprid may be less effective than foliar applications, probably because black pecan aphids ingest lower volumes of sap than other aphid species. Foliar applications may help to slow the development of resistance to imidacloprid, because aphids are not subjected to sublethal doses of imidacloprid, which may be the case with soil application.

Use insecticides that preserve beneficial insects because beneficial insects will decrease aphid numbers over time.

Common name Amount per acre REI‡ PHI‡
(Example trade name)   (hours) (days)

UPDATED: 12/15
Calculate impact of pesticide on air quality
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.
 
A. SPIROTETRAMAT
  (Movento) 6–9 fl oz 24 7
  MODE-OF-ACTION GROUP NUMBER1: 23
  COMMENTS: Do not spray directly or allow to drift onto blooming crops or weeds where bees are foraging.
 
B. PYMETROZINE
  (Fulfill) 4 oz 12 14
  MODE-OF-ACTION GROUP NUMBER1: 9B
  COMMENTS: A selective feeding blocker. Low toxicity to beneficial insects, but do not apply when bees are actively foraging.
 
C. IMIDACLOPRID
  (various) Label rates 12 See label
  MODE-OF-ACTION GROUP NUMBER1: 4A
  COMMENTS: Soil-applied formulations of imidacloprid must be applied preventively before monitoring indicates a need; use if aphids have been a chronic problem in past years. Resistance has been observed in New Mexico. Foliar applications may help to slow the development of resistance to imidacloprid because aphids are not subjected to sublethal doses (as may be the case with soil applications). Do not spray directly or allow to drift onto blooming crops or weeds where bees are foraging.
 
D. DIMETHOATE
  (Dimethoate E267) 1 pt 48 21
  MODE-OF-ACTION GROUP NUMBER1: 1B
  COMMENTS: Ground application only. Do not spray directly or allow to drift onto blooming crops or weeds where bees are foraging.
 
E. POTASSIUM SALTS OF FATTY ACIDS#
  (DES-X, M-Pede) Label rates 12 0
  MODE-OF-ACTION GROUP NUMBER1: unknown
 
F. AZADIRACHTIN#
  (Neemazad 1EC, Neemix 4.5) Label rates 4 0
  MODE-OF-ACTION GROUP NUMBER1: un
  COMMENTS: For larval stages.
 
G. NARROW RANGE OIL# Label rates See label 0
  MODE OF ACTION: Contact including smothering and barrier effects.
  COMMENTS: Although research has not been done in pecans, in other tree crops oil is used to suppress aphids, while preserving beneficials. In organic crops, check with the certifier to determine which products are organically acceptable.
 
H. CHLORPYRIFOS + GAMMA-CYHALOTHRIN*
  (Cobalt) 26-57 fl oz 24 28
  MODE-OF-ACTION GROUP NUMBER1: 1B + 3A
  COMMENTS: Highly toxic to bees. Do not spray directly or allow to drift onto blooming crops or weeds where bees are foraging.
 
I. CHLORPYRIFOS*
  (Lorsban Advanced, Lorsban 4E) 2–4 pt 24 28
  MODE-OF-ACTION GROUP NUMBER1: 1B
  COMMENTS: Use chlorpyrifos in combination with one of the other insecticides listed in this table. Avoid runoff and drift into surface waters. Certain formulations emit high amounts of volatile organic compounds (VOCs); use low-VOC formulations.
 
Restricted entry interval (REI) is the number of hours from treatment until the treated area can be safely entered without protective clothing. Preharvest entry interval (PHI) is the number of days from treatment to harvest. In some cases the REI exceeds the PHI. The longer of these 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). For additional information, see their website at http://www.irac-online.org/.
# Acceptable for use on organically grown produce. Check with your certifier if use is permissible.

[Precautions]

PUBLICATION

[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Pecan
UC ANR Publication 3456

Insects

R. Heerema, Extension Plant Sciences, New Mexico State University
C. Pickel, UC IPM Program, UC Cooperative Extension, Sutter and Yuba counties
R. A. Van Steenwyk, Environmental Science, Policy, and Management, UC Berkeley

Acknowledgment for contributions to Insects:
G. S. Sibbett, UC Cooperative Extension, Tulare County

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