Whitefly
Pest Tiny white flies that suck sap and coat plants with sticky honeydew.
What to look for
Clouds of tiny white flies rise when you brush the plant. Leaves become sticky and covered in sooty black mould, and growth slows. Common on tomatoes, cucumbers, aubergines and brassicas.
When: Spring to autumn, all year under heat.
How to prevent it
- Keep the greenhouse clean and free of weeds and old plant debris.
- Hang yellow sticky traps to monitor and catch adults.
- Clear old brassica stalks in winter to remove overwintering whitefly.
How to deal with it
- Release the parasitic wasp Encarsia formosa in a greenhouse from spring.
- Remove heavily infested leaves and bin them.
- Spray with soft soap, taking care to reach the leaf undersides.
Crops it affects
If you choose to use any treatment, use only products approved for UK home gardens, follow the label and avoid spraying open flowers. See all pests and diseases.