Invasive pest weed Velvetleaf has been found in Otago crops in more than just the two main varieties of infected seed, says the Otago Regional Council.
The Ministry for Primary Industries and regional councils are in the middle of an aggressive search and destroy programme for the plant, which began appearing a month ago in the fodder beet crops grown for winter dairy feed.
The Ministry says it has found velvetleaf on 115 properties nationally, and has 150 staff in the field searching.
The main focus is on thousands of hectares in Southland, Otago and Canterbury, but Velvetleaf has also been confirmed in Marlborough, Manawatu-Whanganui, Hawkes Bay and Waikato.
Otago Regional Council biosecurity manager Jeff Donaldson said the main problems were in imported fodder beet seed in two varieties, Kyros and Bangor, but not only those.
Mr Donaldson said the inspection teams had found and removed velvetleaf from 28 properties in Otago so far, in North, South and Central Otago.
He said his teams should be done with checking 850 hectares of paddock by the end of the week, but may have to do more if new varieties were identified as contaminated.
He believed it is still possible to fully clear the weed from the region.
"We're reasonably comfortable that South Otago properties haven't been seeding, but we have struck some in North Otago and in Central Otago have already dropped some seeds, and that requires a more intensive search.
"We are GPS-ing every plant that we find so that if we can next season we can go back and examine those same sites."
Southland Regional Council said it now had 76 staff in the field searching for velvetleaf in its region, and they had found 60 plants on 10 properties.