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Title: Genetically engineered alfalfa and feral alfalfa plants: What should growers know?

Author
item KESOJU, SANDYA - WASHINGTON STATE UNIVERSITY
item GREENE, STEPHANIE
item BOYDSTON, RICK

Submitted to: Extension Publications
Publication Type: Other
Publication Acceptance Date: 9/2/2015
Publication Date: 7/1/2016
Citation: Kesoju, S., Greene, S.L., Boydston, R.A. 2016. Genetically engineered alfalfa and feral alfalfa plants: What should growers know?. Extension Publications. PNW685:1-9.

Interpretive Summary: The western United States is the most important production area for both alfalfa forage and alfalfa seed. A GE trait for resistance to glyphosate (GR), was available to farmers briefly from 2005 to 2007. In 2011, GR alfalfa received final approval for commercial production. In 2014, GE low lignin alfalfa was deregulated and will be available commercially in the near future. Alfalfa is a cross pollinated crop, pollinated mainly by bees. Recognizing the risk of gene flow between GE and non GE varieties especially in areas where alfalfa seed and hay are grown for the export market, which has low tolerance for GE presence, industry has developed best management practices to support the coexistence of GE and non GE alfalfa producers. Of particular concern is GR feral alfalfa in conventional and organic alfalfa seed growing regions. Therefore, an important management practice is to control feral alfalfa around both seed and hay fields to minimize the movement of GE traits into the conventional seed production stream. Feral plants can be controlled by eliminating old alfalfa fields by mechanical removal by tillage, transporting seed in spill proof containers, repeated and timely mowing of road verges, herbicide application such as aminopyralid, dicamba, clopyralid, and 2,4-D, and integrated weed management (tillage with herbicides). Application of glyphosate herbicide alone should be avoided. The addition of alfalfa in revegetation seed mixes should also be avoided, especially in areas where GE -sensitive alfalfa seed is produced.

Technical Abstract: Alfalfa (Medicago sativa subsp. sativa L) is the world’s most important forage crop. The western United States is the most important production area for both alfalfa forage and alfalfa seed. Alfalfa was the first major perennial genetically-engineered (GE)crop and a GE trait for resistance to glyphosate (GR), was available to farmers briefly from 2005 to 2007. In 2011, GR alfalfa received final approval for commercial production. In 2014, GE low lignin alfalfa was deregulated and will be available commercially in the near future. Alfalfa is a cross pollinated crop, pollinated mainly by bees. Recognizing the risk of gene flow between GE and non GE varieties especially in areas where alfalfa seed and hay are grown for the export market, which has low tolerance for GE presence, industry has developed best management practices to support the coexistence of GE and non GE alfalfa producers. Feral alfalfa is commonly observed along roadsides, irrigation ditches, and unmanaged habitats in alfalfa growing regions. Feral alfalfa can contribute to pollen contamination and potentially lower genetic purity in alfalfa seed production fields when it grows in the vicinity of foraging pollinators working alfalfa seed fields. Of particular concern is GR feral alfalfa in conventional and organic alfalfa seed growing regions. Therefore, an important management practice is to control feral alfalfa around both seed and hay fields to minimize the movement of GE traits into the conventional seed production stream. Feral plants can be controlled by eliminating old alfalfa fields by mechanical removal by tillage, , transporting seed in spill proof containers, , repeated and timely mowing of road verges, herbicide application such as aminopyralid, dicamba, clopyralid, and 2,4-D, and integrated weed management (tillage with herbicides). Application of glyphosate herbicide alone should be avoided. The addition of alfalfa in revegetation seed mixes should also be avoided, especially in areas where GE -sensitive alfalfa seed is produced.