SHARING OPTIONS: The ability of blackgrass to multiply means that a single plant could get this bad in a field in just two seasons. While blackgrass is a growing concern on this island, it has long been a serious issue in Britain and the problems and experiences of dealing with the weed are recalled in this article. Blackgrass (Alopecurus myosuroides) is the most important herbicide-resistant weed in Europe, occurring in at least 10 countries. In Britain, it occurs on at least 20,000 farms in 35 counties and mainly in autumn-sown crops. It is a very competitive weed and populations have the potential to increase rapidly, due to its ability to produce high seed numbers. Its aggressive growth pattern means that yield losses can be substantial.