PEST MANAGEMENT DECISION GUIDE: GREEN AND YELLOW LIST
Whiteflies on tomato
- Remove bean residues and bury or burn
- Plant in well prepared fertile land to promote plant vigour
- Cover nursery with agro nets (size 400 µm) for 3-5 weeks to exclude whiteflies from the crop
- 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 around the edge of the field
- 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
- Puparium: flat, irregular, oval shape, 0.7 mm long
- Look for whitish brown and pear-shaped eggs on the under side of leaves
- 15 days after germination 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.
- 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 at about 1 per 5 plants.
- 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
- Use liquid soap spray at rate of 3 table spoons per litre of water
- Alternate active ingredients to prevent development of resistance
- Wear protective clothing
- Spray early morning or late evening to avoid harming bees
- Dispose properly to avoid aquatic contamination
Spray Azadirachtin 0.03% (50 ml/20L water) 15 days when symptoms appear
Not classified by WHO, but considered unlikely to present acute hazard in normal use. PHI 3 days, REI 1 day. Toxic to fishes
Dimethoate (250g/l) + Cypermethrin (35g/l)
WHO Class II (Moderately hazardous); Maximum 3 applications per season. Apply in the morning or later in the day. PHI 14 days, REI 24 hours. Eye and skin irritant. Highly toxic to bees and other non-target arthropods. Toxic to aquatic organisms. Avoid using near water ways.
CREATED/UPDATED: July 2017
PRODUCED BY: Plantwise
©CAB International. Published under a CC-BY-SA 4.0 licence.