Will Herbicide Resistance Ultimately Benefit Agriculture?

Abstract

From 60 to 70% of the pesticides used in production agriculture in developed countries are herbicides. Herbicides have helped farmers to increase yields while reducing labor. Without herbicides, labor would be a major cost of crop production in developed countries. The relatively low food prices in these countries can be partly attributed to the effectiveness of herbicides. However, the potential environmental and toxicological costs of herbicides have raised questions about our agricultural dependence on these magic bullets. In developed countries, herbicide resistance may ultimately change the economic and technological equations to favor an agriculture less dependent on chemical inputs. Compared to insecticides, resistance to herbicides has evolved very slowly, principally because of the longer life cycle of weeds compared to insects. However, after a relatively long lag phase, the number of cases of herbicide resistance in developed countries continues to grow logarithmically, threatening the use of several herbicide classes over wide areas. Growing multiple resistances exacerbate the situation. Farmers and the herbicide industry have been slow to confront the situation, and, in many places, are not effectively implementing prevention and/or amelioration strategies. Compared to past years, few new herbicides with new molecular target sites are on the horizon to substitute for herbicides or herbicide classes to which economically important weeds have evolved resistance. At the present growth rate, the problem of evolved herbicide resistance will become a major concern of most farmers in developed countries in the near future. Thus, herbicide resistance of weeds may eventually be the biggest impetus for developing methods of weed management that rely less on herbicide inputs.