The effects of cutting and asulam on numbers of frond buds and biomass of fronds and rhizomes of bracken Pteridium aquilinum

Abstract

SUMMARYThe effects of cutting and the herbicide asulam for the control of a dense uniform stand of bracken Preridium aquilinum were investigated experimentally over a 6 —yr period in Norfolk, England. Bracken is a particularly difficult species to control by either mechanical or herbicidal means because of its extensive and complex rhizome network, containing large reserves of dry matter and a large number of frond buds. Cutting bracken in the summer removed dry matter from the system and reduced frond vigour but did not reduce the number of frond buds to a critical level. Whereas the first few cuts substantially reduced the standing crop of fronds, relatively stable standing crops of fronds were observed in future years despite continued cutting. Asulam caused a 99% reduction in the standing crop of fronds in the year after spraying, but in the absence of further treatment, fronds recovered to pre‐spray levels after 6 yr. Asulam caused severe localised damage to frond buds and rhizome apices, but otherwise the rhizome network remained intact. New sections of frond bearing rhizome (short shoots) developed on storage rhizome (long shoots) deep in the soil of both the asulam plots and those cut.