Miscanthus×giganteusResponse to Tillage and Glyphosate

Abstract

Miscanthus is a perennial, rhizomatous C4 grass grown in the European Union and studied in the United States as a bioenergy feedstock. U.S. farmers might be more willing to grow this perennial species if methods for its control were established. Experiments were conducted from 2007 to 2009 to evaluate methods to control miscanthus. As glyphosate rate increased from 0 to 3.6 kg ae ha−1in a greenhouse trial, miscanthus dry weight decreased. Aboveground biomass in the summer following treatments decreased 82, 77, and 95% with fall, spring, and fall followed by spring applications of glyphosate (1.7 kg ae ha−1), respectively, compared with nontreated plots in field experiments. Summer shoot count was reduced by 41% compared with the nontreated control with fall followed by spring glyphosate applications. A second field experiment demonstrated that spring tillage with one or two spring glyphosate applications (2.5 kg ae ha−1application−1) reduced aboveground dry biomass by 94 and 95%, respectively, and reduced miscanthus shoot number by 38 and 67%, respectively, in the same growing season. These experiments suggest that although glyphosate and tillage can reduce miscanthus biomass, complete control of a mature stand likely will require more than one growing season.

Rotating a Field of Mature Miscanthus × giganteus to Glyphosate‐Resistant Crops

“…These rhizomes were then susceptible to drying and freezing. These results confirm the conclusion of Anderson et al (2011) that tillage is a critical component in efforts to control M. × giganteus .…”

“…Emergence of new M. × giganteus shoots continued throughout the growing season each year. Anderson et al (2011) also observed varying degrees of M. × giganteus regrowth with tillage and glyphosate treatments the year following treatments, indicating that control efforts need to be sustained for more than one season. Similar observations have been reported with other perennial grasses such as Johnsongrass (Parochetti et al, 1975), wirestem muhly (Lingenfelter and Curran, 2007), common reed (Ailstock et al, 2001; Derr, 2008a; Rensburg, 1996), reed canarygrass ( Phalaris arundinacea L.) (Annen et al, 2005), and giant reed (Spencer et al, 2008).…”

“…A search of literature investigating M. × giganteus control produced limited results. Anderson et al (2011) found that fall followed by spring applications of glyphosate at 1.73 kg ae ha −1 each or spring shallow tillage (10‐cm depth) with one or two glyphosate applications at 2.53 kg ae ha −1 significantly reduced the aboveground dry weight and shoot number of M. × giganteus the summer following treatments. Anecdotally, Harvey and Hutchens (1995) noted that M. × giganteus is sensitive to glyphosate and Powlson et al (2005) commented that M. × giganteus rhizomes were not difficult to destroy with plowing.…”

Evaluation of herbicide efficacy and application timing for giant miscanthus (Miscanthus x giganteus) biomass reduction

“…During this time, carbohydrates, along with the herbicides, are translocated to the rhizomes. However, Anderson et al (2011) did not achieve adequate control of giant miscanthus with glyphosate applied in fall or spring.…”

“…In a greenhouse study, Anderson et al (2011) determined that immature giant miscanthus shoot dry weight decreased 59% when treated with an application of glyphosate at 3.6 kg ha −1 . However, in a separate field study, the same researchers found no reduction of shoot numbers when treated with a single application of glyphosate at 2.5 kg ae ha −1 in the spring or fall.…”