Herbicide damage

also called Weedkiller damage, Aminopyralid contamination, Herbicide drift

Twisted, cupped, fern-like new growth caused by weedkiller drift, a contaminated sprayer, or manure and compost tainted with hormone herbicides.

Disorder Serious Doesn't spread

What you'll see

New leaves narrow, twisted, cupped or fern-like, with parallel veins instead of a normal net
Stems curl, thicken or grow in corkscrews, and fruit is distorted or hollow
Tomatoes, potatoes, beans and peas hit hardest, often across a whole bed or row
Seedlings emerge stunted and thread-like in beds mulched with tainted manure
Growth off a spray drift is worst on the side facing the treated area

Why it happens

Hormone-type weedkillers throw growth into overdrive and deform it. The three routes are spray drifting from a neighboring lawn or field, a watering can or sprayer used earlier for weedkiller and not cleaned, and — most insidious — aminopyralid residues in manure, hay or grass clippings that pass through the animal and survive composting to poison the plants they are spread on.

Drift comes on warm, breezy days when lawn or path weedkillers are applied nearby. Manure contamination shows in spring as seedlings and tomatoes go into distorted growth in beds dressed with bought-in or stable manure the winter before.

Treating it

Stop using the suspect manure, compost or mulch at once and do not spread any more
Water affected plants well and wait — mild cases can grow out of it as clean new growth appears
Pull and bin, not compost, badly deformed edible crops rather than eat distorted fruit
Keep a never-for-weedkiller watering can and sprayer, clearly marked, separate from all others
Report suspected contaminated manure to the supplier so the source can be traced

Keeping it away

Source manure from a known supplier and ask whether the pasture was sprayed with hormone herbicides
Test suspect manure first by sowing a few broad beans or tomatoes in it before using it widely
Never use lawn mowings for a few mowings after treating the lawn with weedkiller
Apply weedkillers only in still conditions, well away from beds and on a windless day
Compost tainted material is not the answer — aminopyralid can persist for a year or more, so keep it off the garden entirely

Who gets it

Tomatoes, potatoes, beans, peas, carrots and other legumes and solanums are the most sensitive indicators; roses and vines show drift readily too.