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How to Manage Pests
UC Pest Management Guidelines
Caneberries
Greenhouse Whitefly
Scientific Name: Trialerodes vaporariorum
(Reviewed 12/09,
updated 1/10,
corrected 1/10)
In this Guideline:
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Greenhouse whitefly adults lay masses of minute, elliptical eggs on the undersides of leaves. After
hatching, the whitefly larva goes through four instars of development, the last of which is often
called the "pupal" stage and is most identifiable by long, waxy
filaments around the margin of the body and red eyes. The adult emerges from
this state and is a tiny, white insect that is about 0.06 inches (1.5 mm) long.
It has four membranous wings that are held parallel to the top of the body and
covered with white wax. The wings partially fold over one another. Adult
whiteflies occur in dense colonies on the undersides of leaves in newer growth
of caneberries and fly when the leaves are disturbed.
Development of the
greenhouse whitefly from egg to adult takes as little as 18 days, if
temperatures and host plant conditions are ideal. Ideal temperatures for
fastest development are between 80° and 90°F.
Greenhouse whiteflies can be a problem in raspberry and blackberry
crops. They tend to favor succulent, actively growing plant tissue. They damage
plants by feeding on the sap, which reduces plant vigor but most harm is caused
by the exudation of sticky honeydew. When this exudate is deposited on fruits,
it makes the fruit less attractive and marketable. Honeydew also promotes the
growth of black sooty mold on fruits and leaves, which sharply reduces fruit
quality. Although greenhouse whitefly is capable of transmitting viruses, it
has not been associated with any significant viruses in caneberries grown in
California.
A management program in caneberries for whitefly can benefit from an
integrated approach that incorporates cultural, biological, and chemical
methods. Avoid disruptions of native predator and parasitoid populations, along
with applying cultural controls whenever possible.
Biological Control
Natural enemies of
whitefly include Encarsia, Eretmocerus,
Prospaltella, bigeyed bugs, minute
pirate bugs, and lacewing
larvae. Up to 40% of whitefly can be parasitized
and predated in certain areas of the Central Coast. However, releases of large
numbers of predators or parasites for whitefly control have not been successful
in California caneberries.
Cultural Control
Normal pruning of
primocanes and removal of dead floricanes in caneberries can reduce the buildup
of greenhouse whitefly populations. It is important to note that the host range
of greenhouse whitefly is quite broad and includes alfalfa, avocados, beans,
cucumbers, eggplants, grapes, lettuce, melons, peas, peppers, potatoes,
strawberries, tomatoes, and many ornamental crops. Monitor whitefly activity in
adjacent fields, and initiate any control measures when those crops are being
destroyed or degraded to the point where whiteflies begin to migrate out.
It can be useful to
establish a program that denies whitefly populations any viable host for a
period of time. Although such gaps in cropping may be difficult to justify
economically, they will significantly reduce whitefly populations.
Organically Acceptable Methods
Cultural and biological
controls are organically acceptable methods, as is the use of insecticidal
soaps and neem oil.
Monitoring and Treatment Decisions
There is as of yet no
treatment threshold for whitefly in caneberry, but chemical treatments may be
necessary when there are moderate to large populations of whiteflies, resulting
in honeydew on fruit during periods of warmer weather.
| Common name |
Amount/Acre |
R.E.I.+ |
P.H.I.+ |
| (trade name) |
|
(hours) |
(days) |
|
| When
choosing a pesticide, consider information relating to impact
on natural enemies and honey bees as well as the environmental
impact. Not all registered pesticides are listed. Always read label of
product being used. |
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| A. |
AZADIRACHTIN |
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(AZA-Direct)# |
11.5–42 oz |
4 |
0 |
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MODE
OF ACTION GROUP NUMBER1: un |
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COMMENTS:
Apply as a ground application with up to 100 gal water/acre; repeat applications every 7 to 10 days or as the situation warrants. |
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. . . or . . . |
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(Neemix 4.5)# |
4–16 fl oz |
12 |
0 |
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MODE
OF ACTION GROUP NUMBER1: un |
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COMMENTS:
Foliar application to control larvae and nymphs. Apply in ground application
with a minimum of 30 gal water/acre; repeat application every 7 to 10 days. This is a regulated product in an organically certified crop. |
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| B. |
INSECTICIDAL SOAP# |
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(M–Pede) |
2.5 oz/gal water |
12 |
0 |
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MODE OF ACTION: A contact insecticide with smothering and barrier effects. |
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COMMENTS: Use minimum of 50 gal of water per acre. |
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| C. |
NEEM OIL# |
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(Trilogy) |
1–2 gal/100 gal water |
4 |
0 |
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MODE OF ACTION: Unknown. A botanical insecticide. |
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COMMENTS:
Provides suppression of whitefly. Apply in a ground application with a
minimum of 25 gal water/acre. Make sprays on a 7- to 14-day interval,
depending on the severity of the pest problem. As with other oil products,
time applications to early morning/late evening to minimize the potential for leaf burn. |
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| D. |
CARBARYL* |
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(Sevin) XLR Plus |
1–2 qt |
12 |
7 |
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(Sevin) 4F |
1–2 qt |
12 |
7 |
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MODE
OF ACTION GROUP NUMBER1: 1A |
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COMMENTS:
Apply with sufficient water carrier to obtain thorough and uniform coverage,
repeat applications as necessary up to a total of 5 times of no less than
every 7 days. The XLR Plus formulation is the least toxic to honey bees when
direct application to bees is avoided and the spray residues have dried. Apply from late evening to early morning when bees are not foraging. |
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UC IPM Pest Management Guidelines: Caneberries
UC ANR Publication 3437
Insects and Mites
M. P. Bolda, UC Cooperative Extension Santa Cruz County
E. J. Perry, UC Cooperative Extension Stanislaus County
L. J. Bettiga, UC Cooperative Extension Monterey County
Acknowledgment for contributions to Insects and Mites:
R. M. Tyler, UC Cooperative Extension Santa Cruz County
E. Show, Driscoll Strawberry Associates Inc., Watsonville, CA
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