Some Southland and Otago farmers have received specialist advice from PGG Wrightson Seeds after a ''fundamental error'' when hundreds of farmers inadvertently sowed and grew herbicide-tolerant swedes linked to cow diseases and deaths in 2014.
At the end of February, after the bulbs of the plants started appearing, the company learned 556 farmers were sold HT-S57 after paying for a new seed variety, Hawkestone yellow-fleshed Cleancrop swede.
PGG Wrightson Seeds New Zealand general manager David Green said many affected farmers could take the ''generic advice'' already available, particularly in terms of transitioning swedes.
But company staff had visited up to 30 farms since the mistake was identified where ''specific advice'' and ''a more customised approach to manage their crops'' was required.
''Who are we to say what people's attitude to risk should be?'' he said. ''It's all very well to say we could get a normal winter with good hard frosts and everything's OK, but people have got to prepare in the way they feel comfortable.''
DairyNZ regional team leader for Southland-South Otago Richard Kyte said hard frosts would benefit those farmers who had planted the swedes, which would start to mature in spring.
Once the leafy material of the winter feed has matured, the stems, leaves and flowers of the herbicide-tolerant swedes are more likely to have toxic levels of glucosinolates.
''It'll be interesting to see where it goes before spring because there's certainly a lot of these swedes in - there have been issues during the winter in the past.''
Federated Farmers Otago dairy chairman Stephen Crawford said for dairy farmers in Otago the timing ''couldn't be worse''.
''You have the drought issue, and you have the M. bovis [Mycoplasma bovis] issue and it's meaning that people have way fewer options than they would have in a normal year - it's a bad year for it to happen.''
PGG Wrightson discontinued the HT-S57 variety last year.
