An assessment of aerially applied asulam as a method of long-term bracken control

The vegetation of 117 bracken-dominated sites that had been sprayed with asulam from the air over a wide range of dates was recorded. There is a high variability in initial efficacy and sites displayed considerable differences in regeneration in the years following treatment. Sites treated more than 10 years previously all showed good control of bracken. The absence of sites where bracken has regenerated completely was attributed to either respraying at a later date or the poor records kept of previous unsuccessful control measures. There was also a high degree of variation in the amount and type of herbaceous vegetation present below untreated bracken. The data presented suggest that aerial spraying of bracken with asulam can be a long-term and cost-effective control method. However, in the light of experimental results from other studies, the success of an individual operation is critically dependent on the initial efficacy of treatment, the initial floristic composition (if any) and suitable follow-up management.