How to Manage Pests

UC Pest Management Guidelines

Caneberries

Greenhouse Whitefly

Scientific Name: Trialeurodes vaporariorum

(Reviewed 12/09, updated 3/10)

In this Guideline:


Description of the Pest

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.

Damage

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.

Management

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 per acre R.E.I.‡ P.H.I.‡
(example trade name)   (hours) (days)

  Calculate impact of pesticide on air quality
 
The following are ranked with the pesticides having the greatest IPM value listed first—the most effective and least harmful to natural enemies, honey bees, and the environment are at the top of the table. When choosing a pesticide, consider information relating to air and water quality, resistance management, and the pesticide's properties and application timing. Not all registered pesticides are listed. Always read the label of the product being used.
 
A. AZADIRACHTIN
  (AZA-Direct)# 11.5–42 oz 4 0
  MODE OF ACTION GROUP NUMBER1: un
  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.
  . . . or . . .
  (Neemix 4.5)# 4–16 fl oz 12 0
  MODE OF ACTION GROUP NUMBER1: un
  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.
 
B. INSECTICIDAL SOAP#
  (M–Pede) 2.5 oz/gal water 12 0
  MODE OF ACTION: A contact insecticide with smothering and barrier effects.
  COMMENTS: Use minimum of 50 gal of water per acre.
 
C. NEEM OIL#
  (Trilogy) 1–2 gal/100 gal water 4 0
  MODE OF ACTION: Unknown. A botanical insecticide.
  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 or late evening to minimize the potential for leaf burn.
 
D. CARBARYL*
  (Sevin) XLR Plus 1–2 qt 12 7
  (Sevin) 4F 1–2 qt 12 7
  MODE OF ACTION GROUP NUMBER1: 1A
  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.
 
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.
* Permit required from County Agricultural Commissioner for purchase or use.
# 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 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: Caneberries
UC ANR Publication 3437

Insects and Mites

  • M. P. Bolda, UC Cooperative Extension, Santa Cruz County
Acknowledgment for contributions to Insects and Mites:
  • E. Show, Driscoll Strawberry Associates Inc., Watsonville, CA
  • E. J. Perry, UC Cooperative Extension, Stanislaus County

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