For ecological and visual reasons many groups and individuals will prefer not to use herbicides. However, their use will allow more efficient clearance, and lengthen the period before repeat clearance is necessary. Since 1986, all pesticides, including herbicides, have been classified as either for professional or amateur use. Only a person who has obtained a certificate of competence can use a pesticide for professional (or ‘agricultural/horticultural’) use.
In practical terms this may limit most groups to those herbicides classified for amateur use. These are usually obtainable in garden centres, and often have the same active ingredient as the professional equivalent but at a lower dilution. If in any doubt, check with your local office of the Ministry of Agriculture, Fisheries and Food.
Safety precautions
These apply to both amateur and professional pesticides.
- Keep herbicide concentrates in their containers. Read and follow the manufacturer’s advice.
- Provide soap, clean water and towel for washing hands and other exposed skin in case of spillage, and for after work and before meals. As a second best use a waterless skin cleanser and paper towels.
- Mix herbicide solutions in a workshop where there are washing facilities. Wear disposable plastic gloves and a face shield when mixing concentrates and wash immediately if you splash yourself.
- Wear suitable protective clothing at all times. For stump treatment, knee length wellington boots and chemical resistant gloves are essential, and waterproof leggings are advisable. For spraying, wellington boots, chemical resistant gloves, waterproof over-trousers and jacket are essential, and a face shield and ori-nasal mask are recommended. Take care not to come into contact with contaminated parts of protective clothing when taking it off.
- Take the herbicide solution to the work site already mixed, either in the sprayer, or in plastic screw top containers, clearly marked, for stump treatment.
- Never leave herbicides on the path overnight.
- Avoid contamination of waterways.
- Use sprayers only in calm weather to reduce the risk of chemical drift.
- Store herbicides and protective clothing away from foodstuffs and out of the reach of children and animals. Store in a locked and labelled cupboard.
- If a person who has been using chemicals falls ill or is suspected to have ingested some chemical, give first aid and call a doctor immediately, or take the person to hospital. Ensure the doctor knows which chemical is suspected.
Disposal of herbicides and containers
Minimise disposal problems by buying and mixing only what you need.
Rinse the empty concentrate container with water and use the rinsings on the target vegetation, or allow to soak into bare earth, away from a drain or ditch. Empty containers should be punctured or crushed but leaving the labels legible. Empty containers are accepted at most licensed disposal sites but check first with the waste disposal department of your local authority. Unwanted concentrates and diluted herbicides may also be accepted, but in some areas you may have to pay for a specialist contractor to dispose of them. Suppliers may take back unopened, unwanted concentrates.
Detailed advice is contained in ‘Code of Practice for the Safe Use of Pesticides on Farms and Holdings’ (MAFF Publications, London SE99 7TP).
Instructions for use
Herbicides must always be used in strict accordance with the manufacturer ’s instructions.
Manufacturer ’s information should always be studied carefully, not only for safety reasons, but also for the most effective and economical use of the product.
Non-woody growth
Nettles, brambles and other non-woody growth can be sprayed with a translocated herbicide. A herbicide containing glyphosate (Roundup) is suitable.
In general, translocated herbicides are most effective if sprayed while the plant is in active growth and before it flowers. Spraying too early in the season means that insufficient herbicide is absorbed to kill the plant. After flowering, the plant is no longer actively growing and translocation will be less effective. The treated vegetation may need to be left for up to four weeks before the roots are killed, when the dead top growth can be removed.
For path clearance work, the most efficient use of the herbicide must be balanced against the need to make the path passable. This may mean that the best method is to spray the secondary growth of vegetation which has been cut about four weeks previously. Food reserves of the plant are weakened by the initial cutting, and it is easier to reach and treat effectively the new growth, than a tall, dense mass of vegetation. This also avoids the problem of leaving large stands of brown and dying vegetation, which looks very unsightly. A herbicide can also be used for complete control of growth along fences where neighbouring landowners complain of weed spread.
Japanese knotweed is difficult to control, and should be sprayed at its maximum growth in July, and then left for about four weeks before it is cut down. If spraying is done thoroughly, this can kill the plant in one application. A scarlet dye is available from Hortichem which can be mixed with the herbicide to make it easier to see where you have sprayed. Anything less than thorough spraying of full growth will mean re-growth and further spraying later in the season or in following years. In order to keep a path in use, it may be necessary to cut along the line of the path and spray the remainder one year, and then spray the old path line the following year.
Bracken
Asulam (Asulox) is a professional herbicide which is fern specific. It is used to treat bracken at the stage when the fronds are fully expanded but not lignified. There should follow a 95% reduction in the number of fronds the next year, but unless trampling is heavy, the remainder will re-invade over the next four or five years. Spot treatment of re-invading fronds in the second year after the initial treatment, combined with an increased level of trampling, should give sufficient control. Glyphosate also controls bracken, but being non-specific, will affect surrounding vegetation.
Use a knapsack sprayer, and spray only on a dry day. Do not cut the treated bracken for at least four weeks, to allow translocation of the herbicide to the rhizomes.
Stumps
Where the site is suitable, stumps can be destroyed without using chemicals.
Where necessary, stumps of trees and shrubs can be treated to prevent or reduce re-growth with a herbicide containing either ammonium sulphamate (Amcide), or glyphosate (Roundup). The procedure for treatment in both cases is as follows:
- Mix the herbicide solution according to the manufacturer’s instructions.
- Cut the stump as low as possible to minimise the area which needs treating.
- Empty sufficient herbicide for one application into an open container, and paint it on the stump and basal bark, to the point of run-off. This should be done as soon as possible after the stump is cut, as healing processes which seal the stump begin immediately it is cut. Alternatively, the solution can be applied using a garden hand sprayer. Label the sprayer with a permanent marker, and do not use for any other purpose.
Amcide can also be applied as crystals, which should be placed in drilled holes, 25mm diameter and 50mm deep. A 150mm stump should have four holes. Cover the filled holes with stones to keep the rain out, or the crystals will become diluted and ineffective.
