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PEST MANAGEMENT DECISION GUIDE: GREEN AND YELLOW LIST

Whiteflies on tomato

Bemisia tabaci
Zambia
  • Remove tomato residues and volunteer tomatoes and bury.
  • Plant varieties which are resistant to whitefly and the viruses it can transmit.
  • Plant tomatoes 0.5-2 feet apart with at least 3 feet between rows.
  • Use a shade net (size 400 µm)/tunnel for 3-5 weeks while in nursery to prevent attack by whiteflies.
  • Transplant shortly after or during the rainy season.
  • Use white/black inert plastic mulch 10-20 days after transplanting which attracts and kills whiteflies.
  • Conserve natural enemies (wasps, ladybirds) by mulching or leaving a natural hedge of flowering plants (e.g. Tithonia, Lantana) along the edges to offer them refuge.
  • Plant repellent crops such as coriander or Mexican marigold after 3-4 rows of tomato to repel the whiteflies.
  • Whiteflies are sucking insects that can transmit viruses to plants.
  • Adults are white tiny flies of about 1 mm long. The body and wings are covered in a powdery, waxy secretion, white to slightly yellowish in colour.
  • Larva: yellow-white scales, 0.3-0.6 mm long.
  • Puparium: flat, irregular, oval shape, 0.7 mm long.
  • Eggs: Pear-shaped, 0.2 mm long.
  • After transplanting monitor weekly until harvest.
  • Search for leaves with whitefly groups (they are mainly on underside of leaves). They will fly when you shake plants.
  • Yellowing, curling, crumpling of leaves occurs at heavy infestation.
  • Whiteflies can transmit viruses which cause virus disease. Leaves will have yellowish green mosaics.
  • Action threshold level is 10-20 plants with symptoms and/or at least 20 whiteflies on at least 10-20 plants/acre.
  • Use yellow sticky traps (1 per 5 plants) to catch adult whiteflies.
  • Spray Beauveria bassiana products during the early morning or late afternoon (check product labels for dosage) to kill larvae and adult pests. Re-apply if needed after 21 to 28 days.
  • Introduce natural enemies such as predatory mites or parasitic wasps to attack eggs and reduce the pest population.
  • Use hot pepper spray at rate of 30 chopped peppers in warm water. Soak for 1 day, dilute in 10 L water and add 20 drops of liquid soap before spraying to kill larvae.
  • Use liquid soap spray at rate of 3 table spoons per litre of water to remove and kill any larvae or adults present on the crops.
  • When using a pesticide or botanical, always wear protective clothing and follow the instructions on the product label, such as dosage, timing of application, pre-harvest interval, max number of sprays, restricted re-entry interval. Do not empty into drains and water sources.
  • WHO toxicity class II pesticides might not be allowed in local IPM programme.
  • As B. tabaci appears to have developed resistance to all groups of pesticides, farmers must rotate insecticides following an IPM schemes.
  • Acetamiprid 25g/L; foliar spray.
  • WHO Class II - Moderately hazardous, inhalation toxicity. Apply when whiteflies appear, one or two additional applications could made based on scouting. Pre-harvest interval (PHI) 21 days, Restricted re-entry interval (REI) 7 days.
  • Spray Azadirachtin based products 0.03%, 15 days after transplant ; foliar spray.
  • Not WHO classified, but considered unlikely to present acute hazard in normal use. PHI 3 days, REI 1 day. Toxic to fishes.
AUTHOR(S): CABI

CREATED/UPDATED: July 2017
PRODUCED BY: Plantwise

©CAB International. Published under a CC-BY-SA 4.0 licence.