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How to Manage Pests

UC Pest Management Guidelines


Silverleaf whitefly adult.

Eggplant

Silverleaf Whitefly

Scientific Names: Bemisia argentifolii (= B. tabaci, Biotype B)

(Reviewed 4/10, updated 4/10)

In this Guideline:


DESCRIPTION OF THE PESTS

Several species of whiteflies may infest eggplants, but silverleaf whitefly is the primary one. Whiteflies are found mostly on the undersides of leaves. They fly readily when plants are disturbed.

The tiny, elongated eggs hatch into a first larval stage that has legs and antennae and is mobile. Both legs and antennae are lost after the first molt and subsequent stages remain fixed to the leaf surface. Adults are tiny (0.06 inch, 1.5 mm long), yellowish insects with white wings. Silverleaf whiteflies hold their wings somewhat vertically tilted, or rooflike, over the body; the wings do not meet over the back but have a small space separating them.

DAMAGE

Whiteflies damage eggplants by sucking enormous quantities of sap and covering plants with sticky honeydew. Black sooty mold grows over the honeydew, lowering the photosynthetic capacity of the plant and making the fruit unattractive. Currently, no virus problems associated with whiteflies have been reported on eggplant.

MANAGEMENT

Whitefly populations are not consistent from year to year, so monitoring is important in detecting and preventing the development of populations in any given year. In addition, an integrated pest management program for whiteflies includes following good cultural practices, such as host-free periods, and using pesticides only when necessary.

Biological Control
Silverleaf whitefly is an introduced pest that has escaped its natural enemies. Some indigenous native parasites and predators do attack it, but do not keep it below damaging numbers.

Cultural Control
Adult silverleaf whiteflies are repelled by silver- or aluminum-colored mulches. Place reflective polyethylene mulches on planting beds before transplanting to significantly reduce rate of colonization by whiteflies and delay the buildup of damaging numbers of early season whiteflies by 4 to 6 weeks. The mulches lose their effectiveness when more than 60% of the surface is covered by foliage or if dust or soil cover the reflective surface.

Organically Acceptable Methods
Cultural control as well as sprays of insecticidal soaps and certain oil sprays are acceptable for use on organically certified produce.

Monitoring and Treatment Decisions
Routinely check field margins for whiteflies; these areas are usually infested first. Be especially alert for rapid population build up when nearby host crops are in decline. During these critical periods, check eggplant fields twice weekly. Sticky traps may be useful in detecting initial whitefly migrations into fields. If populations are high, consider a treatment. Insecticidal soaps and oils are not as effective as the other materials and require frequent application and good coverage.

Common name Amount/Acre** R.E.I.+ P.H.I.+
(trade name)   (hours) (days)

  Calculate impact of pesticide on air quality
When choosing a pesticide, consider information relating to impact on natural enemies and honey bees and environmental impact. Not all registered pesticides are listed. Always read label of product being used.
 
A. IMIDACLOPRID
  (Admire Pro) 7–10.5 fl oz 12 21
  MODE OF ACTION GROUP NUMBER1: 4A
  COMMENTS: Apply as a soil application according to label directions. See label for information on preventing the development of resistance in whitefly populations to this material. To reduce the potential for the development of resistance, avoid the use of neonicotinoids both as a soil and a foliar application on the same crop.
 
B. PYRIPROXYFEN
  (Knack) 8–10 fl oz 12 14
  MODE OF ACTION GROUP NUMBER1: 7C
  COMMENTS: An insect growth regulator that is not harmful to most beneficials. Research has not been done in California regarding the efficacy of this insecticide in eggplants, but it has proven effective in other crops.
 
C. ACETAMIPRID
  (Assail) 70WP 1.1–1.7 oz 12 7
  MODE OF ACTION GROUP NUMBER1: 4A
  COMMENTS: Apply in a minimum finished spray volume of 5 gal/acre by aircraft or 20 gal/acre by ground. Do not make more than 4 applications/season or exceed 0.3 lb a.i./acre/season. To reduce the potential for the development of resistance, avoid the use of neonicotinoids both as a soil and a foliar application on the same crop. Research has not been done in California regarding the efficacy of this insecticide in eggplants, but it has proven effective in other crops.
 
D. NARROW RANGE OILS#
  (Saf-T-Side, Ultra-Fine Oil,
  Organic JMS Stylet Oil) 1% solution or less 4 0
  MODE OF ACTION: Contact including smothering and barrier effects.
  COMMENTS: This material requires frequent applications and thorough coverage. Check with certifier to determine which products are organically acceptable.
 
E. INSECTICIDAL SOAP#
  (M-Pede) 1% solution or less
(1.28 oz/gal water)
12 0
  MODE OF ACTION: A contact insecticide with smothering and barrier effects.
  COMMENTS: This material has no residual and requires frequent applications and thorough coverage.
 
** See label for dilution rates.
+ Restricted entry interval (R.E.I.) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Preharvest interval (P.H.I.) is the number of days from treatment to harvest. In some cases the REI exceeds the PHI. The longer of two intervals is the minimum time that must elapse before harvest.
# Acceptable for use on organically grown produce.
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/.

[Precautions]

PUBLICATION

[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Eggplant
UC ANR Publication 3475
Insects and Mites
R. H. Molinar, UC Cooperative Extension Fresno County
J. L. Aguiar, UC Cooperative Extension Riverside County
M. J. Jimenez, UC Cooperative Extension Tulare County
P. B. Goodell, UC IPM, Kearney Agricultural Center, Parlier

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