As many as 34 foreign weed species which slipped into New Zealand in a border breach last year could now be in private gardens.
Ministry of Agriculture and Forestry officials yesterday confirmed that scenario was possible and urged gardeners to take care when disposing of unfamiliar weeds.
The weeds entered the country through two October shipments of coir fibre (also called coco-peat and extracted from the outer husks of coconuts) from Sri Lanka.
They were then included in potting mix sent to at least 300 nurseries, most in the North Island. MAF was notified of the breach in February when a Waikato nursery worker noticed strange weeds sprouting in potting mix.
MAF spokeswoman Annie Wright told the Herald yesterday the weeds could now be in private gardens. A booklet helping people identify the weeds was expected to be printed within the next week.
She urged gardeners to dispose of any strange weeds by incinerating them or putting them in council rubbish bags. "But definitely not throwing them over the fence or composting them. This can assist their spread."
But there was little chance the breach could be the New Zealand agricultural sector's equivalent to rock snot or bee virus varroa, she said.
Most of the weeds were tropical species that would not survive in New Zealand conditions. Those that would could be managed "under existing weed control programmes run by the industry".
Since being alerted, MAF had inspected nine nurseries, finding the weeds in five of them. Normal nursery practice was going a long way to tackling the establishment of those weeds, she said.
The department had chosen not to issue a product recall or inspect all nurseries for weeds "because of the already widespread distribution of the material and the length of time that coco peat has been imported into New Zealand".
Ms Wright stressed coir fibre was traditionally deemed a "safe" product, as it was biologically dead.
The weeds had come as "attachments" to the fibre in the shipments, she said.
