Chilli leaf curl virus

the youngest leaves at the top of the plant curl upward and cup like a spoon, go crinkled and puckered, and turn yellow — often yellowest between the veins. The new leaves also come out smaller than normal.

the joints along the stem shorten, so the plant bunches up into a tight, stunted little bush instead of growing tall and open. Any fruit it sets is few, small and twisted, and a plant infected while young may set almost no chillies at all.

Turn over the top leaves and gently tap the plant: if a little cloud of tiny white flies, each about the size of a pinhead, puffs up, those are whitefly. Underneath you may also see their flat, pale, scale-like young ones stuck to the leaf, plus sticky leaves and black sooty mould where the flies have fed.

with mite damage (leaves curl downward and go bronze, brittle and coppery underneath, and the plant recovers once the mites are gone) or with weedkiller drift (a whole patch of plants twist and cup all at once just after spraying nearby, then slowly grow out of it). Leaf curl virus curls upward, spreads plant to plant over days, comes with whiteflies, and its deformed new growth never recovers.

The danger window is from the seedling stage right through the first month after planting out — young plants that get infected then are the ones that never recover. Check every few days, and more often in hot, dry weather, when whiteflies are at their worst. Never plant out a seedling that is already curled.

Walk a big "W" across the field so you cover all four corners and the middle, not just the row beside the path. Make about 10 stops, and at each stop check the youngest top leaves of a few plants.

At each plant, tap the growing tip and watch for the white cloud of flies, then turn over the top 2–3 leaves to look for whitefly and their pale flat young ones, and check those young leaves for upward curling and yellowing. Hang a few yellow sticky traps among the plants — whiteflies are drawn to yellow, so a rising catch on the traps tells you the flies have arrived.

Pull out the very first plant you find with curled, cupped, yellow leaves, the same day you see it. And the moment you spot whitefly on the crop — even a few — start acting on them, especially in the nursery and first month.

Where you can get it, plant a tolerant or resistant chilli or pepper variety. Under heavy whitefly pressure this is your strongest and longest-lasting protection, because the plant shrugs off the virus even when whiteflies bite it.

Raise your seedlings under fine insect-proof netting so whiteflies cannot reach them in the nursery — their most vulnerable time. In the field, lay a reflective or silvery mulch (even bright straw helps) to confuse the flies, clear the weeds in and around the plot (weeds hide the virus between crops), and do not plant a new chilli crop right next to an old chilli or tomato crop — the old crop hands the virus and the flies straight over to the new one.

The moment you find a curled, stunted plant, pull it out and carry it out of the field in a bag (don't just drop it, or the whiteflies move onto the next plant), then burn or bury it. Every infected plant you leave standing is a factory feeding the flies that infect the rest. Keep your yellow sticky traps up to knock down flying adults as well.

An insecticide for whitefly control kills the flies, but remember it does not cure the virus — a plant that is already curled stays sick — so a spray only slows the spread and must go together with clean/resistant seed and roguing, never on its own. Whiteflies get used to a chemical fast (they build resistance), so rotate to a different chemical group each time — never the same spray twice running — and aim it at the leaf undersides, where the flies hide.

Cover your skin, eyes, nose and mouth; spray in the cool of the morning or evening with the wind behind you; keep the spray off food, off water, and away from children and bees; and respect the pre-harvest interval — the set number of days you must wait between your last spray and picking the chillies. Wash yourself and your clothes afterwards.

If most of your young plants are already curled and stunted, no spray will bring them back — a virus cannot be undone. Clear out the badly infected plants, protect any that are still clean, and start the next crop fresh: a resistant variety, a netted nursery, clean ground well away from the old plot, and whitefly control from day one. Nursing a field of infected plants only feeds the whiteflies that will infect your next crop.