Asulam – the need for this bracken beater

Bracken is a plant we are used to seeing in the Border hills, writes Derek Robeson of SAC Conservation.

Up until now it has been kept under control by various methods – key among them being by application of the chemical asulam. However, on December 31 its use was banned across Europe.

It is now illegal to sell or transfer asulam, or even to promote its use. Chemical which has already been purchased can still be used legally, but the use-up period ends on December 31 this year. From January 1 next year it will be illegal to use or store asulam anywhere in the EU.

Why has it been banned? Asulam is used widely across the world for broadleaved weed control. In Scotland it is used principally as a selective control agent for bracken. All chemicals have to be licensed and re-registration of asulam was required. Because of the range of uses for asulam it was decided that the re-registration should be based on its use for control of weeds in spinach.

The EU Food Standards Agency expressed concern about a possible human health risk and a ban was imposed.

United Phosphorus (owner of the brand Asulox) has agreed to apply for re-registration, but this is unlikely to happen before 2016. Meanwhile, an emergency authorisation will be applied for to cover application each summer for a 120-day use between June and September. This, however, is unlikely to be before 2013.

What are the implications of the ban? Bracken is generally found on steep and inaccessible hill slopes. Traditionally, it has been controlled by applications of asulam by helicopter. Because asulam is a highly-selective weed control agent, it has little effect on other plants.

It is estimated that Scotland has about 2,000 square kilometres of bracken-covered land. This could increase to 6,000 square kilometres (seven per cent of land area) if left unchecked. Bracken can quickly spread through underground rhizomes at the rate of more than a million per year. Due to its dense canopy cover it can choke out more desirable plants such as heather and native wild flowers and grasses, making the hills a less wildlife-friendly place.

If emergency authorisation for the use of asulam each summer is not successful, then it is quite possible that many Border hill valleys will appear quite different in time.