Potential gene flow is a major source of concern in the Imperial Valley especially between seed fields. Some Imperial growers produce forage and seed from the same field; cutting hay early and then letting the same field go to seed for seed production.

Until recently, technology could not accurately measure gene flow from a GMO field to a non-GMO field.

Finding answers to the gene flow question is the goal of a research team led by UC alfalfa geneticist Larry Teuber. The group began quantifying RR alfalfa gene flow in Kings County in 2003.

Trials conducted in western Fresno County from 2006 to 2008 included an almost 6-square mile commercial alfalfa seed production area with no forage production fields in the vicinity.

Shannon Mueller, UCCE Fresno County farm advisor, tracked honey bees in the fields marked with either a colored powder or protein dust; a process developed by James Hagler of the USDA-ARS in Maricopa, Ariz.

The marking techniques allowed researchers to determine how far honey bees flew from hives to forage in surrounding alfalfa seed fields. Collected seed samples were analyzed to determine the gene flow percentage. Results suggest gene flow declines with increased distance from the RR alfalfa source field.

“The gene flow at 1 mile was less than one quarter of 1 percent,” Mueller said. “The gene flow at 3 miles was three-hundredths of 1 percent. No gene flow was detected at 5 miles.”

Mueller says the RR alfalfa trait is easy to detect in seed samples and provides an accurate measurement of gene flow.

“It is up to the industry to establish a threshold they will accept,” Mueller said. “Research results can help determine the distance between fields to achieve the desired result.”

Gene flow discussions in relation to the recent deregulation of RR alfalfa are not unique to RR alfalfa. Pollen has always moved between neighboring fields, yet researchers lacked the tools to accurately measure the gene flow. Technological advancements have changed that.