Conservation tillage triazine herbicides

The triazine herbicides have revolutionized agricultural production of corn and more than 40 other crops. The yield increases, less labor-intensive production, and use for erosion control in conservation tillage are all benefits of the tri-azines, especially atrazine and simazine. Registered since the late 1950s, atrazine is still a mainstay of corn production and likely the most studied herbicide by regulatory agencies. 

Triazine herbicides are particularly well suited for conservation tillage because they provide foliar and residual control of a broad spectrum of weeds. Atrazine, simazine, and metribuzin are used in com, atrazine and propazine in sorghum, metribuzin in soybean, and simazine reduces tillage required for weed control in many perennial and tree crops. Atrazine is also used extensively in chemical fallow cropping systems in rotations involving corn, sorghum, and wheat. Cyanazine was also used extensively in corn and cotton until 2002. 

Conservation tillage, which relies heavily on triazine herbicides, produces many environmental benefits. Herbicides allow tillage to be reduced or, in some cases, eliminated except for disturbance caused by the planter. 

Triazine herbicides have been important tools in the development and implementation of conservation tillage systems. Postemergence and residual activity, low vapor pressure, weak adsorption to surface crop residue, root uptake, broad weed control spectrum, and crop safety make these herbicides compatible with the high crop residue conditions of conservation tillage. 

The use of conservation tillage, made possible by triazine and other herbicides, has dramatically reduced soil erosion and its on- and off-site impacts. Significant benefits from the use of herbicides such as the triazines can be realized because conservation tillage reduces erosion, sedimentation, and flooding. By creating a crop field with many features comparable to those in natural areas, conservation tillage also provides other benefits to the environment and to wildlife. 

Triazine herbicides provide cost-effective, broad-spectrum weed control and are key tools in conservation tillage. Although the chemical alternatives to the triazines are more costly and generally less efficacious, they are considerably more reliable as weed control methods and more compatible with current farming operations than available nonchemical weed control methods. Even as more com acreage shifts to herbicide-tolerant com, the need remains for residual herbicides such as the triazines to manage resistant weeds and to avoid the need for multiple tillage passes for weed control. 

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