Technical Abstract: Modern agricultural weed management practices rely significantly on the use of synthetic herbicides. While there is a large number of commercial active ingredients, these represent relatively few chemical classes that affect an even fewer number of target sites. While herbicides account for more than 60% of all pesticides used in agriculture in the USA, the plant protection industry is undergoing a rapid transformation that has destabilized the traditional herbicide market. Meanwhile, the need for new molecular target sites and new chemistries has not abetted, as more and more weed species evolve resistance to specific herbicides, primarily via single mutations at the target site, potentially rendering them cross-resistant to entire chemical classes. Natural products have been a valuable source of many pesticides. However, mode of action studies are difficult because of the thousands of putative molecular target sites that exist in plants. Some of the advantages of studying the mode of action of natural products is that these phytotoxins tend to inhibit target sites that are different from those affected by synthetic herbicides. Therefore, studying the mechanisms of action of natural products enhances the likelihood of discovering new mechanisms of action.