The 55 properties infected with velvetleaf in Southland last year continue their battle with the pest, working with Environment Southland to develop farm management plans.
In March last year, the first confirmed cases of velvetleaf in the South Island were notified to the Ministry for Primary Industries (MPI).
Less than a month later, it was confirmed the pest had been brought into New Zealand in contaminated fodder beet seeds.
In Southland, about 200 plants were discovered and the same in Otago.
Environment Southland senior biosecurity officer Randall Milne said the key thing in Southland's fight against velvetleaf had been catching the plants before they produced seeds.