Soil properties, sulfonylurea herbicides

Conclusion. In this chapter, we have attempted a broad overview of the biochemical and environmental properties of the sulfonylurea herbicides. The history of these herbicides is distinguished by the apparently endless variation in structure leading to new weed control spectra, crop selectivities and soil degradation properties. They have already achieved significant use in j ctice, and it is likely that Dr. Levitt s discovery will continue to yield new herbicide tools offering viable solutions to the needs of world agriculture and of society. 

The preceding chapters have highlighted some of the diverse substitutions on the sulfonyl fragment of sulfonylurea herbicides that impart an unprecedented level of activity, as well as some of the subtle structural changes that have led to quite different crop selectivities and soil residual properties. This chapter reviews some of the modfications to the heterocyclic amine fragment of sulfbnylureas that have been investigated and found to impart herbicidal activity at low application rates. 

Although studies on the degradation mechanism of SL-950 have just been started, judging from the fiu t that SL-950 has almost same dissociation constant (pKa 4.6) as SL-160, 81 950 is expected to follow a similar chemical degradation pathway. The short-residual properties of SL-160 have been described in the chapter of Haga et al. If 81 950 behaves similarly in soil, it will have a persistence profile that is very attractive for rotational cropping. Such properties may be considered important for future sulfonylurea herbicides. 

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