Clayton Plant Protection, a Dublin-based agri-chemicals company, has successfully fought off a challenge from the US giant Monsanto to its right to formulate and sell a herbicide called "Rhizeup" in the British market.

The glyophosate herbicide, originally developed by Monsanto and sold under the brand name "Roundup", came off patent in 1991. Clayton sought and was granted a licence from the British Ministry of Agriculture, Food and Fisheries to formulate and sell the product under the name "Rhizeup".