Gene flow between sugar beet and weed beet

Gene flow between transgenic sugar beet and weed beet was investigated at t he farm scale. Evidence was given of gene flow between bolters of the crop that occurred at low density in a 1 ha field and weed beet growing spontane ously in an adjacent set-aside field. Up to 0.8% of the weed progeny was hy brid. A second experiment was specifically designed to check gene flow from a small pollen source of sugar beet to a low density weed beet population. The frequency of hybrids slowed down from 10% three meters away the pollen donor to 1% at 15 m. The effects of wind, distance, weed aggregation, inse cts and genotypes on the hybridization rate are discussed.