Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 7/12/2016
Publication Date: 7/16/2016
Citation: Sandya, K.R., Greene, S.L., Martin, R.C., Kramer, M.H. 2016. Do glyphosate resistant feral plants and hay fields spread the transgene to conventional alfalfa seed fields? Meeting Abstract. North American Alfalfa Improvement Conference, Madison, WI. July 12-14, 2016.

Interpretive Summary: Alfalfa growers are marketing to consumers who do not want genetically engineered traits in the seed and hay they purchase. These consumers comprise export and organic markets. Because alfalfa is an insect pollinated crop, gene flow is a concern. Alfalfa readily naturalizes along roadsides, irrigation ditches, and unmanaged habitats; and feral plants can contribute to gene flow. There is concern that genetically engineered hay fields and feral plants that contain genetically engineered traits may be a source of contamination, however there have been few studies that have examined this. Our objective was to examine the extent that gene flow occurred from genetically engineered feral plants and hay fields to conventional seed fields. Genetically engineered and non-engineered feral plants, seed and hay fields were mapped in Fresno County, CA and Canyon County, ID in spring 2013 and conventional seed fields identified at various distances from feral plants and hay fields identified as genetically engineered. Adventitious presence in the conventional seed fields was examined and related to distance and other attributes that may influence gene flow. The results from our study suggested that there is very low level gene flow from genetically engineered hay fields and feral plants. However, if producers use coexistence best management strategies, levels should not have an economic impact.

Technical Abstract: In addition to meeting domestic needs, large amounts of alfalfa seed and hay produced in the US are being exported overseas. Because alfalfa is an insect pollinated crop, gene flow is a concern. Adding to this alfalfa readily naturalizes along roadsides, irrigation ditches, and unmanaged habitats; and feral plants can contribute to gene flow. The situation has become more complicated since the introduction of genetically engineered (GE) alfalfa to resist glyphosate herbicide. Due to cross contamination of GE traits, many alfalfa producers are impacted by market sensitivity. They are concerned that GE hay fields and feral plants may be a source of contamination, however there have been few studies that have examined this. Our objective was to determine gene flow from glyphosate resistant (GR) feral plants and hay fields to conventional seed fields. Alfalfa feral plants, seed and hay fields were mapped in the Fresno County, CA and Canyon County, ID in spring 2013. GR feral plants and hay fields (source) and conventional seed fields (sink fields), located at various distances from GR sources, were identified. Distance from GR hay fields, distance from GR feral plants, pollinator abundance, elevation, aspect, and slope were also obtained. The results from our study suggests that there is low level gene flow from GE hay fields and feral plants. Gene flow from feral plants may depend on the feral plant population size. It would be prudent for producers of AP-sensitive seed with very low or no tolerance for GE traits to use ASSP AOSCA isolation distances (3.2 km) from any GE alfalfa hay fields or any unmanaged alfalfa feral plants, manage feral plants in the vicinity of seed production fields, and use proper hay harvesting schedule.