Agricultural chemicals supplier Nufarm will develop its own glyphosate-based weedkillers after losing the right to distribute the Roundup brand.
Nufarm has held the right to distribute glyphosate under the Roundup brand, owned by global agricultural biotechnology company Monsanto, in Australia and New Zealand since 2002.
But Monsanto terminated the agreement on Tuesday, sending Nufarm's shares plunging by 12 per cent to close at a 14-month low of $4.85.
Nufarm will stop selling glyphosate under the Roundup brand after August 28.
Managing director Doug Rathbone said the glyphosate market had become increasingly competitive and was generating less value for suppliers in the Australian market.
"The brand premium attached to Roundup has consequently been eroded," he said.
"We will now focus our ongoing investment in glyphosate on Nufarm's own brands where we can build long-term value on a more secure basis and ensure our cost competitiveness."
Monsanto said it had ended the deal with Nufarm following changes in the market.