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How to Manage Pests
UC Pest Management Guidelines
Pecan
Yellow Aphid Complex
Scientific names: Yellow pecan aphid: Monelliopsis pecanis
Black margined aphid: Monellia caryella
(Reviewed 2/07,
updated 2/07)
In this Guideline:
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DESCRIPTION OF THE PESTS
Both the yellow pecan aphid and the black margined aphid are
somewhat similar in appearance and cause similar types of damage. Both species
are yellow with black markings. The amount of black pigmentation varies with
stage of development and time of year, but in general increases from spring to
fall. The cornicles on both species are reduced to pores. Except for the winged
adults, yellow pecan aphids have long setae, or hairs, that tend to stand out
from the body at 45 to nearly 90 degree angles, giving the aphids a pincushion
look. In addition, yellow pecan aphids have red eyes. Black margined aphids
have much shorter setae than yellow pecan aphids and the setae form less than a
45 degree angle with the body. There are multiple generations of both species
each year; populations tend to peak in spring and again in fall.
DAMAGE
Both species primarily feed on the underside of leaves. Black
margined aphids feed on the underside of leaves on major leaflet veins while
yellow pecan aphids feed on the network of small veins located throughout the
leaf. They damage pecan trees by extracting large amounts of photosynthate and
water from leaves, which impairs the growth of both shoots and roots. They also
secrete large amounts of honeydew on to leaves, and the sooty mold that grows
on the honeydew can reduce photosynthetic efficiency.
MANAGEMENT
By choosing insecticides that preserve beneficial insects, aphid
populations will decrease over time.
Before June 1: Treat if honeydew is accumulating.
June 1 to August 15: Treat if the total number of aphids exceeds
an average of 20 per leaf.
August 15 to leaf fall: Treat if the total number of aphids
exceeds an average of 10 per leaf.
| Common name |
Amount/Acre** |
R.E.I.+ |
P.H.I.+ |
| (trade name) |
|
(hours) |
(days) |
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| The following materials are listed in order of
usefulness in an IPM program, taking into account efficacy, impact
on natural enemies and honey bees and the
environment.
|
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| NOTE: Yellow pecan aphid resistance to
insecticides has been a problem in other pecan-growing states. Alternate insecticides with
different mode of action Group numbers, and do not use each more than once a season. |
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| A. |
IMIDACLOPRID |
| |
(Admire Pro) |
7–14 fl oz |
12 |
30 |
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MODE OF ACTION: A neonicotinoid (Group 4A)1
insecticide.
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COMMENTS: Can be used from May 15 to July 15. This formulation
of imidacloprid must be applied preventively before monitoring indicates a need; use if aphids have been a chronic problem in past years. |
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| B. |
DIMETHOATE E267 |
1 pt/acre |
48 |
21 |
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MODE OF ACTION: An organophosphate (Group 1B)1
insecticide.
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COMMENTS: Ground application only. |
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| C. |
CHLORPYRIFOS* |
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(Lorsban) 4E |
1–4 pt/acre |
|
28 |
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MODE OF ACTION: An organophosphate
(Group 1B)1 insecticide.
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COMMENTS: Use chlorpyrifos in combination with one of the other insecticides listed in this table. Avoid runoff and drift into surface waters. |
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| D. |
NARROW RANGE OIL# |
Label rates |
4 |
0 |
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MODE OF ACTION: Contact including smothering and barrier effects. |
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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. |
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| E. |
ENDOSULFAN* |
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(Thionex) 3EC |
1 qt/100 gal |
24 |
See comments |
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MODE OF ACTION: An organochlorine (Group 2A)1
insecticide.
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COMMENTS: Do not apply after shuck split. Do not exceed 2 applications/year or
4 qt/acre/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. |
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![[Precautions]](/IMAGES/btn-precautions_bul.gif)
![[UC Peer Reviewed]](/IMAGES/logo-ucpeerreviewed.jpg)
UC IPM Pest Management Guidelines: Pecan
UC ANR Publication 3456
Insects
R. A. Van Steenwyk, Environmental Science, Policy, and Management, UC Berkeley
C. Pickel, UC IPM Program, UC Cooperative Extension, Sutter/Yuba counties
Acknowledgment for contributions to the insect section:
G. S. Sibbett, UC Cooperative Extension, Tulare County
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