Whitefly
This problem spreads through handling, insects or soil rather than the weather, so there is no live forecast risk — focus on prevention below.
When it strikes
About
Whiteflies are tiny sap-sucking insects that swarm up in clouds when plants are disturbed, thriving in warm weather and greenhouses on tomatoes, brassicas and ornamentals, and spreading viruses.
Symptoms
Clouds of tiny white moth-like insects under leaves; yellowing, wilting and weakened plants; sticky honeydew and black sooty mould on lower leaves.
Organic Treatment
Use yellow sticky traps, spray insecticidal soap or neem on leaf undersides, vacuum adults in the morning, and release Encarsia parasitic wasps in greenhouses.
Chemical Treatment
Insecticidal soaps and oils for light infestations; systemic insecticides for severe greenhouse outbreaks, rotated to manage resistance.
Prevention
Inspect new plants before bringing them in, use yellow traps for monitoring, encourage natural enemies, and avoid excess nitrogen.