ABSTRACT
Natural product-based herbicides are needed by organic and conventional farmers who are either required or want to reduce residues of synthetic pesticides in their crop and/or the environmental impact of weed management. Unfortunately, the few available completely natural product-based herbicides are not efficacious or cost-effective in comparison with synthetic herbicides. The products are mostly natural oils, oil components (primarily terpenes) and organic acids. Highly herbicidal natural compounds exist, but only one of these, bialaphos, is marketed. Glufosinate, a synthetic version of the natural product phosphinothricin, has been a successful herbicide, but it is not considered acceptable for organic production. The HPPD inhibitor herbicides were developed from natural triketones which have the same mode of action. Several highly potent natural phytotoxins have not been commercialized for one or more of three major reasons: 1) mammalian toxicity, 2) expense of production, and 3) intellectual property issues. Nevertheless, there are natural herbicidal phytotoxins for which the problems in commercialization could be overcome with new production technologies.
