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PEST MANAGEMENT DECISION GUIDE: GREEN AND YELLOW LIST

Whiteflies on tomato

Bemisia tabaci
Ghana
  • Remove tomato residues and volunteer tomatoes and bury or burn.
  • 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 white flies.
  • 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.
  • Keep the field weed-free throughout the cropping season since weeds act as alternate hosts and can harbour whitefly-transmitted viruses.
    • Adult: a sucking insect, about 1 mm long. The body and wings are covered in a powdery, white to slightly yellowish in colour.
    • Larva: yellow-white scales, 0.3-0.6 mm long on the underside of leaves.
    • Puparium: flat, irregular, oval shape, 0.7 mm long.
    • Eggs: whitish and 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 and resettle when you shake plants.
  • Yellowing, curling, crumpling of leaves occurs at heavy infestation.
  • 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 at about 1 per 5 plants to capture and kill adult moths.
  • Spray Beauveria bassiana products during the early morning or late afternoon (check product labels for dosage) to kill larvae and adults. 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 liquid soap spray at rate of 3 table spoons per litre of water.
  • 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.
  • Do not use chemicals with the same mode of action year after year as this can lead to resistance, always consult the most recent list of registered pesticides of MODA, Ghana.
  • Spray Azadirachtin 0.03% (50 ml/20L water) 15 days after transplant.
  • Not classified by WHO, but considered unlikely to present acute hazard in normal use. PHI 3 days, REI 1 day. Toxic to fish.
AUTHOR(S): CABI, Patrick Beseh (PPRSD)

CREATED/UPDATED: July 2017
PRODUCED BY: Plantwise

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