Weedkiller damage
Hormone weedkillers used on lawns and fields distort broad-leaved plants at tiny doses. Drift on a breezy day, or manure from animals fed on treated grass, gives tomatoes, potatoes, beans and vines twisted, strap-like leaves.
Roots & damage
What it looks like
New growth comes out wrong while older leaves stay normal.
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Cupped leaves Leaves curl into cups or roll downward. -
Fern-like growth Tomato leaves turn narrow and feathery. -
Strap-shaped leaves Vines and beans make thin, strappy new leaves. -
Twisted stems Stems bend and corkscrew.
How to confirm it
Look for a source and a pattern.
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Recent spraying
A lawn or path treated nearby in the last few weeks.
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Bought-in manure
Several crops in one manured bed all distorted.
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Bean test
Sow broad beans in a pot of the suspect manure; distorted seedlings confirm it.
What to do
There is no cure; the plants either grow out of it or not.
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Wait on light drift
Mildly affected plants often grow normal new leaves.
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Do not eat badly affected crops
Discard produce from severely distorted plants.
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Dig out contaminated manure
Remove what you can and keep turning the soil; the chemical breaks down with time and warmth.
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Tell the supplier
Report contaminated manure or compost so it is traced.
Prevent it next time
- Spray weedkiller only on still days, well away from edible crops.
- Ask where manure came from, and test it before using it widely.
- Never put treated lawn clippings in compost used for vegetables.
What not to do
Do not compost affected plants or manure; the chemical survives composting.
In the growing guides
Where the guides mention it, with plant-specific advice.
Sources
- Weedkiller damage, Royal Horticultural Society
- Weedkiller in manure, Royal Horticultural Society
- Herbicide damage to vegetables, University of Maryland Extension