Stump killing poisons and the industry by Ian Monger

The recent withdrawal of Amcide as a stump killer raises questions for the industry about the legal implications of using stump killing chemicals and the alternative chemicals that might be available. Since suppliers and users are unclear about how the changes might affect them, the AIE has spoken to the Pesticides Safety Directorate to clear things up.

The method chosen to remove a stump depends on many factors, but mechanical removal with a stump grinder is arguably the most effective, safe and efficient. (The Tree Stump Removal article summarises different methods). But access or other restrictions sometimes means that using a poison to kill the cambium, and so prevent growth from the stump, is the only option. LPAs often specify stump poisoning where access is limited.

Ammonium sulphamate-based stump killing products have been used in the industry for many years. Amcide has been the only professional product available, and has been used in the industry since 1964. A range of amateur products have been available to the public (Deep Root, Root Out).

Ammonium sulphamate is a broad-spectrum contact herbicide that controls tough woody weeds, tree stumps and brambles. It has an extremely low toxicity to humans and is considered one of the safest herbicides to use prior to growing edible crops. Soon after the tree is felled, the chemical crystals are poured on the cut surface and covered, then the chemical kills the cambium and prevents regrowth. Beyond the stump, the poison is slowly converted in the ground into the beneficial plant nutrient ammonium sulphate. In a report, the Henry Doubleday Research Association (organic growing research charity) considered it an option where organic control methods had failed.

EC Review Programme

The aim of the EC Review Programme is to reassess and evaluate, to modern safety standards, all pesticides that have been in use prior to 1992. The Review started with a list of 90 active substances selected on the basis of health and environmental concerns and residues in food, and required that the chemical manufacturers submit a 'dossier' of chemical and safety data. The dossier for ammonium sulphamate was never submitted to the Review board (probably because of the chemical manufacturers' commercial or safety calculations), and so the chemical was removed from the approved list and withdrawn from sale.

Ammonium sulphamate has now been completely withdrawn from sale as part of the periodic EC Review Programme. Products containing the chemical can be stored and used until 22nd May 2008. Beyond this date it will be illegal to store or sell any product containing this chemical.

The practicing arborist, or the LPA Tree Officer might ask what the alternative is.

There are 2 'grades' of herbicide which are legally approved for use in the EU: those approved for home garden (amateur) use and those approved for professional (horticultural) use. This is an important distinction, as it is technically illegal for a professional person to use an amateur product in the course of his business or employment.

Amateur products:

These products are available from garden centres and DIY shops, including online. Their use doesn't require specific training because the label is worded so that instructions are easy to follow. If a product can be used on tree stumps this will be specifically stated on the product label. Advice can also be obtained from pesticide companies and gardening organisations. The Crop Protection Association's website allows you to search for approved products on the 'Solve your garden problem' page.

AIE asked the Pesticides Safety Directorate (PSD - an agency of Defra) about the use of amateur products by arborists. They said that although use by professional users of 'amateur' products in 'professional' situations is technically illegal, the PSD hold no objection to such use, provided:

• no safety or environmental concerns were evident;

• the 'professional' user undertaking the work hold a certificate of competence;

• the use satisfied all the conditions of the product's approval; and

• that an appropriate COSHH assessment for that particular use/situation was undertaken.

SBK Brushwood Killer from Vitax Ltd contains triclopyr and is approved for amateur use to kill stumps.

Professional products:

All 'professional' users of pesticides - irrespective of what type of pesticide they are using - are legally required to:

• comply with the requirements of Schedule 3 (Conditions Relating to Consent to the Use of Pesticides) of the Control of Pesticides Regulations 1986 (as amended);

• follow the advice and guidance contained in the 'Code of Practice for Using Plant Protection Products' - Defra's statutory Code of Practice for all professional users of plant protection products in England and Wales (made under the Food and Environment Protection Act 1985, and the Health and Safety at Work etc Act 1974).

This means that, by law, everyone who uses pesticides professionally (which means: 'in the course of his business or employment') must have received adequate training in using pesticides safely and be skilled (competent) in the job they are carrying out.

By law you also need a certificate of competence if you supply, store or use 'agricultural pesticides', including in amenity areas such as parks, streets and sports pitches, in forestry, or in or near water.  Those without such a certificate may work under the direct supervision of someone who holds such a certificate.

Competency in the safe use of pesticides in the UK is assessed by the National Proficiency Test Council (NPTC), through the 'Safe Use of Pesticides' qualification. Certification covers: current laws; health and environmental risks associated with pesticides and their application; safe working practices; emergency action; health monitoring; record keeping; and proper use of equipment for applying pesticides. Download the Safe Use of Pesticides Learner Guide [70KB].

You will need to arrange any training you need, and pass your tests. Training for NPTC certificates of competence is provided by many agricultural colleges, independent training providers and trade associations.

Finally there is no obligation under the pesticides legislation for a person to be in possession of a certificate of competence to use a pesticide in order to purchase such a pesticide although in practice it is becoming much more common for suppliers to only provide professional products to people that do hold such certificates.

Timbrel from Bayer Environmental Science is approved for use as a forestry/industrial herbicide. It contains triclopyr and is approved for professional use to kill stumps. It costs about £90 for 2 litres (Amcide cost about £25 for 3kg). It may be applied immediately after felling; undiluted with a paintbrush, or diluted with paraffin, diesel oil or water with a knapsack sprayer.

(Remember to carry out an additional COSHH assessment if you or your staff plan to use a new herbicide or use a herbicide in a new situation.)