Prospects for Bioherbicides

Abstract

New solutions to weed management are needed now more than ever. Ag retailers, university extension specialists and farmers consider the evolution of herbicide-resistant weeds "one of the most significant developments in agriculture today." Indeed, weed resistance is not just a US problem, but a global one. There are currently 505 unique cases of herbicide resistant weeds globally, with 264 species. Weeds have evolved resistance to 21 of the 31 known herbicide sites of action and to 164 different herbicides. Herbicide resistant weeds have been reported in 95 crops in 71 countries. According to Duke, no new herbicide modes of action have been introduced since the 1980s. Since this paper, only one herbicide with a new mode of action (cyclopyrimorate) has been commercialized. Some major agrichemical companies have announced new discoveries and new modes of action coming in the future, but these are some years off. Given this state of weed management, one would think that biological or natural product herbicides with new modes of action would already be making headway in the market. Unfortunately, few new biological products have been commercialized. The technical difficulty in finding bioherbicides that can compete with the spectrum and price of chemical herbicides has left agriculture with a paucity of new herbicides based on natural products. Most products are targeted at organic agriculture because of their higher manufacturing cost. These products are typically short residual, burndown products that require high volumes and multiple applications. Examples are clove and orange oils. Other natural active ingredients include acetic acid (vinegar), FeHEDTA, NaCl, pelargonic acid, and caprylic and capric acids. This paper reviews the reasons for the lack of new bioherbicides, current and pipeline products and how new technologies may accelerate their progress.