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Weed Control Trends and Practices in North America
Chapter 4
Weed Control Trends and Practices in North America David R. Pike University of Illinois, Champaign, Illinois Ellery L. Knake and Marshal D. McGlamery University of Illinois, Urbana, Illinois
Summary As with any crop production enterprise, the selection of one weed management technique over another is a matter of improving efficiency, economics, environmental stewardship, and soil conservation. From the earliest use of sharpened sticks and iron hoes to today's use of herbicides - technical innovation, culture, inspiration, hard work, and serendipitous discovery have worked together to produce the efficient crop management system we have today. For North American agriculture, these changes came slowly at first. During the Colonial Period, readily available virgin farmland and a paucity of agricultural institutions to disseminate technical knowledge produced few incentives for farmers to change traditional practices. However, as the demands for food and fiber increased in the 19th and 20th centuries, the pace of agricultural invention rose to produce high yields and increase production efficiency. Many of our current technical innovations in mechanical weed control can trace their development from earlier forms of the same tillage device. Even the plows and cultivators used through the 1900s tended to be little more than large, hardened steel replacements of the wooden tools used centuries earlier. On the other hand, herbicides radically changed agricultural production within a few years of their introduction. Novel application equipment is now required by the herbicide user, as is the knowledge to use each new herbicide product effectively. Initially, lack of application equipment and the technical knowledge needed to use herbicides were challenges to growers. Farmer familiarity with fertilizer application boxes on their planters initially resulted in the granular formulation of many herbicides being banded over the crop row. When spray equipment became more widely available, farmers adapted and began to use broadcast applications of postemergence, preemergence, and preplant incorporated herbicides. Evolving tillage practices impacted the timing of herbicide application and whether it was mechanically incorporated. Crop safety, drift injury to nontarget plants, and hazards to the environment and the operator contributed to the complexity of weed management decisions. Products with difficult handling characteristics or narrow tolerances for crop injury were put aside as improved herbicides became available. Weed scientists were struggling to learn when and how to best control weeds and how to best convey information to growers about this important emerging agricultural discipline. A principal issue from the grower's perspective was the ease with which an herbicide could be used to control weeds effectively. Herbicides that would be favored had a broad spectrum of weed control, easily mixed with other herbicides to expand the control spectrum, and could be applied using a number of techniques and application timings. Since their introduction in the 1940s and for the next 60 years, products that exhibited these characteristics, such as the triazine herbicides, came to be the mainstays of the new weed control era. Although herbicides have been an efficient tool for crop production, they have also become an agent of change - increasing productivity, decreasing tillage requirements, facilitating an increase in farm size, and permitting economies of scale. The purpose of this chapter is to examine trends in weed management in North America. A single chapter does not allow us to address in detail all of the important weed management innovations. However, we will point out some of the significant changes, and through the use of examples, suggest some of the factors that have affected the evolution of weed management. For a concise and informative treatment of the history of weed control in Europe from the days of Rome and Greece up to the 19th century, we recommend Smith and Secoy (1981). 45
Weed Control Trends and Practices in North America David R. Pike University of Illinois, Champaign, Illinois Ellery L. Knake and Marshal D. McGlamery University of Illinois, Urbana, Illinois
Summary As with any crop production enterprise, the selection of one weed management technique over another is a matter of improving efficiency, economics, environmental stewardship, and soil conservation. From the earliest use of sharpened sticks and iron hoes to today's use of herbicides - technical innovation, culture, inspiration, hard work, and serendipitous discovery have worked together to produce the efficient crop management system we have today. For North American agriculture, these changes came slowly at first. During the Colonial Period, readily available virgin farmland and a paucity of agricultural institutions to disseminate technical knowledge produced few incentives for farmers to change traditional practices. However, as the demands for food and fiber increased in the 19th and 20th centuries, the pace of agricultural invention rose to produce high yields and increase production efficiency. Many of our current technical innovations in mechanical weed control can trace their development from earlier forms of the same tillage device. Even the plows and cultivators used through the 1900s tended to be little more than large, hardened steel replacements of the wooden tools used centuries earlier. On the other hand, herbicides radically changed agricultural production within a few years of their introduction. Novel application equipment is now required by the herbicide user, as is the knowledge to use each new herbicide product effectively. Initially, lack of application equipment and the technical knowledge needed to use herbicides were challenges to growers. Farmer familiarity with fertilizer application boxes on their planters initially resulted in the granular formulation of many herbicides being banded over the crop row. When spray equipment became more widely available, farmers adapted and began to use broadcast applications of postemergence, preemergence, and preplant incorporated herbicides. Evolving tillage practices impacted the timing of herbicide application and whether it was mechanically incorporated. Crop safety, drift injury to nontarget plants, and hazards to the environment and the operator contributed to the complexity of weed management decisions. Products with difficult handling characteristics or narrow tolerances for crop injury were put aside as improved herbicides became available. Weed scientists were struggling to learn when and how to best control weeds and how to best convey information to growers about this important emerging agricultural discipline. A principal issue from the grower's perspective was the ease with which an herbicide could be used to control weeds effectively. Herbicides that would be favored had a broad spectrum of weed control, easily mixed with other herbicides to expand the control spectrum, and could be applied using a number of techniques and application timings. Since their introduction in the 1940s and for the next 60 years, products that exhibited these characteristics, such as the triazine herbicides, came to be the mainstays of the new weed control era. Although herbicides have been an efficient tool for crop production, they have also become an agent of change - increasing productivity, decreasing tillage requirements, facilitating an increase in farm size, and permitting economies of scale. The purpose of this chapter is to examine trends in weed management in North America. A single chapter does not allow us to address in detail all of the important weed management innovations. However, we will point out some of the significant changes, and through the use of examples, suggest some of the factors that have affected the evolution of weed management. For a concise and informative treatment of the history of weed control in Europe from the days of Rome and Greece up to the 19th century, we recommend Smith and Secoy (1981). 45