Whitefly
Overview
Whitefly are among the most important pests in protected horticulture.
They are especially problematic in: - tomatoes - cucumbers - peppers - aubergines - poinsettia - ornamentals
Whitefly feed on sap and can rapidly build large populations in warm protected crops.
Identification
Adults are: - small white flying insects - commonly found on lower leaves - easily disturbed when plants are moved
Immature stages occur mainly on leaf undersides.
Look for: - adults flying upward - scales on leaves - honeydew - sticky foliage - sooty mould
Damage symptoms
Typical symptoms include:
- yellowing
- sticky leaves
- reduced vigour
- sooty mould
- contamination of fruit and flowers
- weakened plants
Heavy infestations reduce crop quality significantly.
Conditions favouring whitefly
| Condition | Risk |
|---|---|
| Warm protected crops | Very High |
| Crop carryover | High |
| Dense canopy | Moderate–High |
| Long-season crops | High |
| Poor lower-leaf monitoring | High |
Monitoring
Inspect: - lower leaves - old leaves - sticky traps - warm bays - crop edges - carryover crops
Whitefly often establish first on older lower foliage.
Biological control strategy
Whitefly biological control usually works best preventatively.
Useful strategies include: - parasitoids - predatory bugs - trap monitoring - lower-leaf inspections - preserving continuity
Programmes usually struggle once dense lower-leaf reservoirs establish.
Environmental strategy
Useful practices: - removing heavily infested leaves - avoiding crop carryover - improving airflow - preventing dense humid lower canopy - reducing unmanaged reservoirs