Integrating Cereals and Deep Tillage with Herbicide Programs in Glyphosate- and Glufosinate-Resistant Soybean for Glyphosate-Resistant Palmer Amaranth Management

A field experiment was conducted at Marianna, AR in 2012 and 2013 to test various combinations of (1) soybean production systems: full-season tillage (rye plus deep tillage using a moldboard plow), full season (no rye plus no tillage), late-season tillage (wheat plus deep tillage), and late season (no wheat plus no tillage); (2) soybean cultivars: glufosinate or glyphosate resistant; and (3) four herbicide programs for management of glyphosate-resistant Palmer amaranth. At soybean harvest, Palmer amaranth control was 95 to 100% when flumioxazin plus pyroxasulfone was applied PRE. In both years full-season tillage and late-season tillage systems in combination with flumioxazin plus pyroxasulfone applied PRE increased Palmer amaranth control over the same systems in the absence of flumioxazin plus pyroxasulfone applied PRE. The addition of deep tillage in the form of a moldboard plow to the full-season and late-season systems reduced Palmer amaranth densities at harvest. Similarly, Palmer amaranth seed production was often lower in the full-season tillage and late-season tillage systems compared with the full-season and late-season no-tillage systems, regardless of soybean cultivar and herbicide programs. Overall, the use of deep tillage in the full-season or late-season systems in combination with a PRE application of flumioxazin plus pyroxasulfone provided greater control of Palmer amaranth, decreasing both density and seed production and increasing soybean grain yields.