Southland is the latest region where the potentially devastating pest plant velvetleaf has made an appearance.
Environment Southland says a single case of the weed has been identified on a Southland property and farmers who have fodder beet crops are being asked to keep an eye out for any more plants.
Officials thought the serious cropping pest was only in the South Island in North Canterbury and Central Otago, but two outbreaks have also been recently discovered in Waikato.
Environment Southland said this was the first confirmed case in Southland.
It said farmers who planted the specific Kyros and Bangor varieties of imported fodder beet seed were advised to take particular care to look out for the weed in their crops.
Now was a good time to identify any velvetleaf plants in Southland as they stood above the fodder beet crops and were quite distinctive looking, with large, soft velvety leaves.
Environment Southland says now was also an important time to find these annual plants before they seeded and created bigger issues next season.
MPI was investigating how the weed seeds could have entered New Zealand, with the suspect consignments meeting New Zealand's importing requirements and were certified as weed-free by the exporting country.
People who find suspected velvetleaf plants are advised not to pull them out or let stock graze in the area and instead photograph them and send the photo to MPI.
MPI was currently reviewing the import requirements for seed.