How to Manage Pests

UC Pest Management Guidelines

DESCRIPTION OF THE PEST

The black pecan aphid is the only black 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 the first through fourth instars 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. Populations 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

By choosing insecticides that preserve beneficial insects, aphid populations will decrease over time. The following guideline was developed in Texas and has not been proven in California. Usually control is not needed until late in the season, after mid-July. At that time, treat if levels exceed an average of one black aphid per compound leaf.

Common name		Amount to Use**	R.E.I.+	P.H.I.+
(trade name)			(hours)	(days)
The following materials are listed in order of usefulness in an IPM program, taking into account efficacy, information relating to natural enemies and honey bees as well as the environmental impact. Not all registered pesticides are listed. Always read label of product being used.
A.	IMIDACLOPRID
	(Admire Pro)	7–14 fl oz	12	7
	MODE OF ACTION GROUP NUMBER1: 4A
	COMMENTS: This formulation of imidacloprid must be applied preventively before monitoring indicates a need; use if aphids have been a chronic problem in past years.
B.	DIMETHOATE E267	1 pt/acre	48	21
	MODE OF ACTION GROUP NUMBER1: 1B
	COMMENTS: Ground application only.
C.	CHLORPYRIFOS*
	(Lorsban Advanced)	2–4 pt/acre	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.
D.	NARROW RANGE OIL#	Label rates	4	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 populations of aphids, while preserving beneficials. In organic crops, check with certifier to determine which products are organically acceptable.
E.	ENDOSULFAN*
	(Thionex) 3EC	1 qt/100 gal	24	see comments
	MODE OF ACTION GROUP NUMBER1: 2A
	COMMENTS: Do not apply after shuck split. Do not exceed two applications per year or 4 quarts per acre per year. Cannot be applied in any situation where run-off may occur; check with county agricultural commissioner. May not be effective in all areas because of resistance.
**	For dilute applications mix with 330-400 gal water/acre; for concentrate application mix with at least 20 gal water/acre.
+	Restricted entry interval (R.E.I.) is the number of hours from treatment until the treated area can be safely entered without protective clothing. Preharvest entry interval (P.H.I.) is the number of days from treatment to harvest. In some cases the R.E.I. exceeds the P.H.I. 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 are assigned by IRAC (Insecticide Resistance Action Committee). For additional information, see their Web site at http://www.irac-online.org/.
#	Acceptable for use on organically grown produce.

PUBLICATION

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/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

Top of page