Glyphosate-resistant soybeans have been widely adopted by growers due to the benefits of broad-spectrum efficacy, reduced crop injury, and simplification of weed management. Glyphosate-resistant corn has expanded in use in recent growing seasons and as a result, glyphosate is increasingly being depended upon as the primary means of weed management in corn and soybean production.

The widespread use of this technology has produced concerns about the effect of continuous use of glyphosate on weed community composition and the development of new weed problems. The goal of this research was to determine the long-term weed management and agronomic risks in glyphosate-resistant corn and soybean as influenced by intensity of tillage and glyphosate use. Research was conducted at the University of Wisconsin from 1998 to 2006 to determine the long-term effects of primary tillage system and glyphosate use intensity on weed population dynamics in a glyphosate-resistant corn and soybean annual rotation.