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How to Manage Pests
UC Pest Management Guidelines
Cucurbits
Green Peach Aphid
Scientific Name: Myzus persicae
(Reviewed 11/05,
updated 6/08)
In this Guideline:
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The green peach aphid is rather slender in form, light green or
yellowish in color. Winged
adults of the green peach aphid are
pale or bright green and black, with a large dusky blotch on the dorsum of the
abdomen. The immature forms are yellow, pinkish, or pale green. The mature
wingless forms are pale or bright green and have no waxy covering. The tubercules at the base of the antennae grow towards
each other. Populations tend to start on lower leaves and move up the plant.
The green peach aphid occurs throughout California and has a wide host range.
In desert areas, watermelon
mosaic virus,
zucchini yellow mosaic, and papaya ringspot virus are transmitted chiefly by
the green peach aphid. This aphid moves into melon fields in large numbers from
surrounding vegetation, carrying viruses as it moves and feeds from one plant
to another. In the San Joaquin Valley, cucumber mosaic, zucchini mosaic, and
watermelon mosaic are often the most important viruses transmitted by this
aphid.
Silver reflective mulches have successfully been used to repel
aphids from plants, thus reducing or delaying virus transmission. In some areas
of the state, row covers have also been successfully used. Biological control
can have a significant impact on aphid population so be sure to evaluate
predator and parasite populations when making treatment decisions.
Biological Control
Naturally-occurring populations of the convergent
lady beetle,
Hippodamia convergens, may provide effective control in early spring.
Releases of this beetle are not effective, however, because it generally does
not remain in the field following release. Other general predators, such as lacewing and
syrphid larvae, and parasitic wasps, including Aphidius,
Diaeretiella,
and Aphelinus species, also attack aphids. Biological control is not effective in reducing
virus transmission by this aphid.
Cultural Control
To exclude green peach aphid, place row covers over the seed bed
following planting and leave them in place until first bloom. Row covers are
not recommended in the San Joaquin Valley. Silver reflective plastic mulches
applied at planting are effective in repelling aphids from plants, thereby
reducing or delaying virus infection. Mulches help plants get off to a healthy
start, and are effective until expanding foliage covers the reflective surface.
Mulches may need to be removed in the desert areas when summer temperatures are
excessive for optimal growth of plants. However, in the Central Valley and
cooler areas, mulches have not caused plant damage in the summer; in fact, they
improve soil moisture and nutrient retention, which may further aid plant productivity.
Control weeds along ditch banks, roads, in farmyards, and other
noncultivated areas that contribute directly to the aphid problem. Planting a
habitat for beneficial insects, such as sweet alyssum, around the field may be
helpful. Delay planting until warm temperatures (80° to 85°F) occur and the
spring flight of aphids is over. Do not overfertilize with nitrogen.
Organically Acceptable Methods
Biological and cultural controls and treatments of insecticidal
soaps and certain narrow range oils are acceptable to use in an organically
certified crop.
Monitoring and Treatment Decisions
The decision to treat for aphids is based mainly on visual counts;
measurable thresholds have not been researched. It is important to treat early
to insure that the aphids do not build up to high levels. Early treatment does
not prevent virus introduction; treating, however, may help reduce spread of
the virus if aphid colonies are present. Be aware, however, that parasites and
predators, if present, may prevent an infestation from becoming established
throughout a field, thus eliminating the need to treat.
| Common name |
Amount/Acre |
R.E.I.+ |
P.H.I.+ |
| (trade name) |
|
(hours) |
(days) |
|
| When choosing a pesticide, consider information relating
to water quality and impact on natural
enemies and honey bees.
|
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| A. |
IMIDACLOPRID |
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MODE OF ACTION GROUP NUMBER1: 4A |
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(Admire) 2F |
16–24 fl oz |
12 |
21 |
| |
COMMENTS: Apply at planting or transplanting and incorporate
into root zone. Repeat applications of any neonicotinoid insecticide (imidacloprid-Admire;
thiamethoxam-Platinum) can lead to resistance to all neonicotinoids. Alternate neonicotinoids with an
insecticide that has a different mode of action to help delay the development of resistance. |
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| B. |
THIAMETHOXAM |
| |
(Platinum) |
5–8 fl oz |
12 |
30 |
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MODE OF ACTION GROUP NUMBER1: 4A |
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COMMENTS: At seeding or transplanting, apply in sufficient
water to ensure uniform application and incorporation into the soil. Repeat
applications of any neonicotinoid
insecticide (imidacloprid-Admire; thiamethoxam-Platinum) can lead to
resistance to all neonicotinoids. Alternate neonicotinoids with an insecticide that has a different mode of action to help delay the development of resistance. |
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| C. |
METHOMYL* |
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(Lannate) LV |
1.5–3 pt |
48 |
1 (1.5 pt or less) |
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3 (more than 1.5 pt) |
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MODE OF ACTION GROUP NUMBER1: 1A |
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COMMENTS: Labeled for use on melons, cucumbers, and summer
squash only. Apply early and as needed 7 days later. Repeated use of this material is very disruptive to beneficials. |
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| D. |
OXYDEMETON METHYL* |
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(MSR Spray Concentrate) |
1.5–2 pt |
72 |
see label |
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MODE OF ACTION GROUP NUMBER1: 1B |
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COMMENTS: Apply in sufficient water for complete coverage, but
not less than 1 gal/acre. No more than 1 application/season on squash and
pumpkin, 2 applications/season on watermelons and cucumbers, and 3 applications
on other melons. Repeated use of this material is very disruptive to beneficials. |
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| E. |
INSECTICIDAL SOAPS# |
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(M-Pede) |
1–2% solution |
12 |
0 |
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MODE OF ACTION: A contact insecticide with smothering and barrier effects. |
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COMMENTS: This material will reduce populations temporarily, but has no residual and requires repeat applications and thorough coverage. |
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| F. |
NARROW RANGE OILS# |
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(Saf-T-Side, JMS Stylet Oil) |
3–6 qt/100 gal |
4 |
0 |
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MODE OF ACTION: Contact including smothering and barrier effects. |
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COMMENTS: Stylet oil is not acceptable for use on an
organically certified crop. Oil will reduce populations temporarily, but has
no residual and requires repeat applications and thorough coverage. Oils may cause phytotoxicity problems; exercise care when using these materials. |
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UC IPM Pest Management Guidelines: Cucurbits
UC ANR Publication 3445
Insects and Mites
E. T. Natwick, UC Cooperative Extension, Imperial County
L. D. Godfrey, Entomology, UC Davis
C. G. Summers, Entomology, UC Davis/Kearney Agricultural Center, Parlier
J. J. Stapleton, UC IPM Program, Kearney Agricultultural Center, Parlier
Acknowledgment for contributions to Insects and Mites:
R. L. Coviello, UC Cooperative Extension, Fresno County
C. B. Fouche, UC Cooperative Extension, San Joaquin County
J. B. LeBoeuf, AgriData Sensing, Inc., Fresno
M. Murray, UC Cooperative Extension, Colusa/Glenn counties
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