Development of a Novel Paddy Rice Herbicide Propyrisulfuron (ZETA-ONE)

Herbicides have made a large contribution to reducing the workload of crop production. While herbicides with various modes of action are currently used, sulfonylurea herbicides, which were developed starting in the 1970s, are in widespread use worldwide, and they hold the central position in weed control in Japan as paddy rice herbicides. However, as is the fate of agricultural chemicals that are used intensively, the problem of resistance to sulfonylurea herbicides began to appear in the latter half of the 1990s. While propyrisulfuron (Fig. 1) is a compound that has a sulfonylurea skeleton, it has the unique characteristic of exhibiting herbicidal activity against weeds that show resistance to commercialized sulfonylurea herbicides. This chemical controls a wide spectrum of paddy weeds at low dose rates. In addition, because of its physical and chemical properties, it can be provided in the three major formulations used in paddy rice culture in Japan, namely granular formulation, suspension concentrate and jumbo formulation. Furthermore, it shows a high level of safety for mammals, birds and aquatic organisms. Herbicide products containing this compound were registered as agricultural chemicals in Japan on December 13, 2010. Moreover, development of this compound is also moving forward in South Korea, and practical evaluations are being conducted in other parts of the Asian region. In the following, we will report on the discovery of propyrisulfuron, its history of development and the knowledge obtained through the processes involved.