ABSTRACT
The technology of genetic engineering is introducing a wide variety of traits into crop plants. One of the first to be field tested is herbicide resistance. This chapter discusses the problems of herbicide- resistant weeds (HRWs) and how these might arise from the widespread development and employment of herbicide-resistant crops (HRCs). The potential for gene flow via pollen depends on three primary factors: the amount of pollen produced; the longevity of pollen; and the means of pollen transport. Secondarily it may be affected by selection on any genes expressed in the recipient gametophyte. Biological problems may arise from the movement of herbicide-resistant genes (HRGs) into wild populations. Where the herbicide is applied, HRGs are expected to be strongly selected for, and population should evolve to contain primarily or entirely plants carrying the HRGs. The economic consequences of HRWs are potentially immense. The chief economic impact of weeds is in agriculture, where they reduce crop yield and quality.
