The effectiveness of glyphosate for controlling Brachypodium pinnatum in chalk grassland

Where Brachypodium pinnatum forms dominant, low diversity stands with distinct boundaries, the herbicide glyphosate is sometimes used, in the UK, to control the species. The effectiveness of glyphosate in reducing B. pinnatum dominance and restoring a species rich chalk grassland community was assessed here by treating B. pinnatum stands at two ancient chalk grassland sites, and monitoring the subsequent development of the plant community, over several years. The rate of re-colonisation of treated stands varied between sites. At both sites many of the species initially colonising treated areas were ruderal or uncharacteristic of the surrounding chalk grassland. Where colonisation proceeded rapidly, ruderal species declined, and chalk grassland species characteristic of the site increased in cover. However, B. pinnatum re-colonised all treated stands even though glyphosate inhibited the germination of its seeds. It is predicted that B. pinnatum will regain dominance following glyphosate treatment, and we suggest that glyphosate should only be used to control B. pinnatum as part of an integrated control programme.