Yellow sticky traps

How it works

Insects navigate towards yellow because it reads as fresh foliage; the glue does the rest. Most valuable as an early-warning system that tells you a problem is starting.

Recipe

Hang or stake cards just above the crop canopy, one per 2-3 square metres.

How to apply

Check twice a week and count what you catch - a rising count means act now. Move them up as plants grow.

Targets — pests

Whitefly, Fungus gnat, Thrips, Leaf miner

Targets — diseases

Not recorded — the field is blank rather than guessed.

Supplies: Yellow sticky traps

Days to harvest after spraying: 0

Best months: not recorded

Cautions

They are indiscriminate and will catch hoverflies, parasitic wasps and the occasional bee. Best inside a greenhouse or polytunnel, and used sparingly outdoors.

The thing people get wrong

Use them as a thermometer, not a cure. Traps never catch enough whitefly to control an infestation, but they tell you it started two weeks before you would have noticed by eye - and that head start is what actually saves the crop.