Hawke's Bay growers say there will be no shortage of vegetables and they support government controls after the second invasive weed slipped border controls this season.
Velvetleaf, which grows 2.5m tall with yellow flowers, has been found in hundreds of properties in New Zealand, including Hawke's Bay.
Blackgrass has been found in a Canterbury cropping farm.
The New Zealand Grain & Seed Association has warned vegetables could be in short supply because the government has announced interim measures restricting seed import.
Restrictions include subjecting all pelleted seed imports to laboratory testing for contaminants and a ban on all fodder beet seed lines known to be contaminated.
Hawke's Bay Vegetable Growers Association chairman Scott Lawson said he did not think there would be a shortage of vegetables - there were few crops being sown this time of year and while most seed was imported there were New Zealand sources.
He said checks and balances would likely be tightened "and if it means a short hold-up to keep those protocols up then that's not a problem".
Velvetleaf incursion was of particular concern because it was more likely to become established in a fodder crop for animals - crops for human consumption had strict care regimes from both growers and processors, he said.
Federated Farmers Hawke's Bay grain and seed spokesman Rob Foley said extra costs for stricter controls were acceptable.
"We don't need weed seeds in New Zealand and it would cost more to try and spray them out and control them," he said.
"I always welcome things the government is doing to protect our borders - we have to look after our own backyard."
Central Hawke's Bay grower Hugh Ritchie said any upfront cost to test seeds was a small price to pay.
"Tightening things up, to make sure these things don't get through, I think is a bloody good thing," he said.
"MAF and MPI are very aware of the need for seed but at the moment they are concerned there seems to be too many of these things crossing our borders.
"The cost of growing vegetables going forward, to combat all these new weeds, would be even worse. The reality is it would probably be cheaper to catch these things at the border."
Seeds might need to be imported uncoated to ensure non-contamination and it is be prudent to be wary of countries' phytosanitary certificates.
"One might argue if the importers did a decent job to start with, in terms of vetting the seed line they are buying, then we might not have these issues."
He said there was a big demand recently for fodder beet for both dairy and drystock but for him there were issues with soil compaction/structure.
"There has been a huge expanse of it and one wonders if the fact of the matter is seed supply started to get smaller, so people took lesser-quality seed."