ACRE Advice

Monitoring large scale releases of genetically modified crops (EPG 1/5/84). Incorporating report on project EPG 1/5/30: monitoring releases of genetically modified crop plants

Advice of the Advisory Committee on Releases to the Environment
under Section 124 of the Environmental Protection Act 1990

ACRE was asked to review the final report of the monitoring of large scale releases of GM oil seed rape grown between 1994 and 2000. The report represents the combined final reports of two separate Defra monitoring contracts run between 1994-1997 and 1997-2000. The final report is available at www.defra.gov.uk/environment/gm/research/epg-1-5-84.htm.

The report considers inter- and intra-specific gene flow by means of cross pollination and also seed dispersal and the persistence of volunteers. The research reported was not deliberately designed to investigate gene flow but took advantage of the results from a programme of monitoring of a series of approved releases of OSR between 1994 and 2000. Monitoring was undertaken at 11 field-scale experimental release sites in total.

The report is divided into several sections including details of methods and sites used, gene flow between crops, gene flow between species - including a specific study of gene flow to weedy Brassica rapa, feral and volunteer rape and conclusions.

The main findings of the report include:

Gene flow between GM and adjacent conventional oil seed rape crops

The occurrence of cross pollination decreased rapidly over a distance of a few metres but was detected at a levels of 0.5% at 250m at one site. Higher levels of out crossing were detected when the GM crops was grown near a varietal association crop. The report concludes that "the results presented show different situations can give very different results under natural field conditions".

Feral and Volunteer oilseed rape

The incidence of transgenic volunteers at sites was monitored for several (up to five) years. The number of volunteers that were detected was variable. In one incidence transgenic oil seed rape volunteers persisted until 2000 at least from a crop harvested in 1996. GM volunteers appear no more persistent than non-GM volunteers. A low level of gene flow was detected from GM oil seed rape to feral rape growing nearby (up to 20m). The report concludes that transgenes can persist in volunteers and feral populations but the level of occurrence is low and the transgenes did not appear to persist.

Interspecific gene flow

Gene flow between GM oil seed rape and Brassica rapa was detected at a site where a small amount of B. rapa was deliberately sown alongside a GM crop, and at another site where GM oil seed rape was sown in an area where weedy B. rapa was a known problem. The report concludes that where B. rapa and oil seed rape (B. napus) are grown together, gene flow will occur. Cross-pollination between oil seed rape and other wild relatives was not detected.