The potential future roles of natural compounds and microbial bioherbicides in weed management in crops

: There is a popular demand for more natural means of pest management, including weed management, as well as a demand by farmers for herbicides with new chemistries and/or new modes of action to which current weed resistances do not apply. Natural compounds offer a source compounds that can either meet these needs in their natural state or as templates for herbicides with better physicochemical properties for field use. In some cases, simply identifying a good herbicide target site with a natural phytotoxin can be valuable, even though that compound is not used as a template for new herbicides. Compared to insecticides and fungicides, natural compounds have been under-utilized for herbicides. Despite their need, living, microbial biocontrol agents have had little impact on weed management in crops, despite decades of research to discover and develop such products. Management of insect and plant pathogens with microbial biopesticides has been much more successful. The reasons for this and possible solutions are discussed. Killed microbial preparations containing potent phytotoxins avoid some of the issues with live microbes, and such products are under development. This type of product can also offer more than one new mode of action in a single preparation. Precision and smart spray systems can improve the economics of both natural product-based herbicides and microbial bioherbicides.