Contents

Executive Summary

1: Introduction

1.1: Objectives

1.2: The PGS Application

1.3: The Hybrid Oilseed Rape System

1.4: Environmental Risks of Herbicide-Tolerance

2: Gene Flow and Hybridisation

2.1: Volunteer and Feral Oilseed Rape

2.1.1: The PGS application

2.1.2: ACRE's view

2.1.3: Other views

2.1.4: Recent developments

2.1.5: Conclusions

2.2: Gene Flow Between Neighbouring Crops

2.2.1:The PGS application

2.2.2:ACRE's view

2.2.3:Other views

2.2.4:Recent developments

2.2.5:Conclusions

2.3: Hybridisation with Wild Relatives

2.3.1: The PGS application

2.3.2: ACRE's view

2.3.3: Other views

2.3.4: Recent developments

2.3.4.1: Spontaneous hybridisation between oilseed rape and wild relatives

2.3.4.2: Frequency of spontaneous hybridisation a. B. rapa

2.3.4.3: Fertility and fitness of hybrids

2.3.4.4: Will GM oilseed rape outcross with greater frequency than conventional varieties?

2.3.5: Conclusions

3: Herbicide Tolerance

3.1: Introduction

3.2: Glufosinate-Tolerant Oilseed Rape

3.2.1: The PGS application

3.2.2: ACRE's view

3.2.3: Other views

3.2.4: Recent developments

3.2.5: Conclusions

3.3: The Effects of Glufosinate Herbicide

4: Risk Assessment

4.1: The 1994/1995 Risk Assessment and ACRE's Remit

4.2: A Revised Assessment of Risk

4.2.1: Volunteers and feral populations

4.2.2: Gene flow and hybridisation

5: References

Table 1: A comparison of the data available in 1998 with that in 1994 (Scheffler & Dale 1994) on hybridisation between oilseed rape, Brassica napus, and its wild relatives (see text for definition of spontaneous)

Table 2a: Percentage of hybrid seed produced in various crosses between Brassica napus and related species

Table 2b: Percentage of hybrid seed produced in various crosses between Brassica napus and related species

Table 2c: Percentage of hybrid seed produced in various crosses between Brassica napus and related species

Table 3: Gene flow between oilseed rape and wild relatives (summary)