Slurry or manure resulting from feeding grass, silage or hay treated with the grassland herbicide, aminopyralid, has been found as the cause of damage to some potato crops this season, SAC and Dow AgroSciences have announced.

SAC was first alerted to the potential problem when it identified unexpected crop damage in several crops earlier this year. After normal emergence an early growth, the developing foliage was discoloured and misshapen. In extreme cases the foliage resembled frond-like growth and top growth was restricted. Damage was sporadic across affected fields.

Investigation suggested the cause was slurry or manure from grass treated with aminopyralid, the active ingredient in Forefront, Halcyon and GF839. Similar damage has been seen previously with clopyralid.

Growers intending either to grow potatoes after grass or if manure or slurry is being applied to ground intended for potatoes from grass-, silage- or hay-fed livestock, should check carefully what herbicides have been used on the grass as there could be following crop or limitations on the slurry or manure use, SAC advises.

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