Herbicide Damage
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
Fix the cause, not the leaf
No spray will help here. The trigger is soil, water supply, nutrition or temperature, so change the growing condition and judge the result on new growth, not on damaged leaves.
Not contagious
Nothing spreads from plant to plant here. Neighbouring plants showing the same signs are reacting to the same soil, water or weather, so fix the cause rather than isolating plants.
Safe to compost
No pathogen carries over on this material, so it can go on an ordinary heap with the rest of the garden waste.
When and where to look
This problem has no weather threshold. Check it on every routine walk round the bed, especially after handling plants and after bringing new stock in.
The signs that lead here
About
Hormone weedkiller damage is regularly mistaken for a virus. It reaches a garden three ways: spray drift from a neighbouring lawn, contaminated manure or grass clippings from treated pasture, and the residue left in a watering can used for weedkiller. Tomatoes are the classic indicator plant.
Symptoms
Leaves become narrow, fern-like and twisted, and stems spiral or fuse. Growing tips cup downwards and fruit is distorted or absent. Unlike a virus there is no mottling or mosaic — the colour stays normal and every plant in the affected area is hit at once.
Organic Treatment
Water plants generously to dilute the residue, do not feed with nitrogen, and remove the worst-affected growth. Mildly affected plants often grow out of it in six to eight weeks. Compost suspect manure for a further year, turning it regularly, and test it by sowing a few broad beans in it before use.
Chemical Treatment
There is no antidote. Activated charcoal worked into contaminated soil binds some residues but is not reliable at garden scale.
Prevention
Keep a separate, clearly marked watering can for weedkiller and never use it for anything else. Ask where manure has come from and whether the pasture was sprayed, avoid using grass clippings from treated lawns as mulch, and never spray hormone weedkillers on a breezy day.