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Protecting British Trees

Typical knapsack spraying operation (30 Kb JPEG)
Typical knapsack spraying operation

The Forestry Commission has 753,000 hectares of woodland which comprises 25% of the total forested area of the United Kingdom (UK) and which represents 3% of the total land area of the UK.

The critical period for weed control is from April to June when we focus on five types of weeds: 

  • grasses, 
  • herbaceous 
  • broadleaved weeds,
  • bracken, heather and
  • woody weeds such as rhododendron.

Weed control can be much easier and cheaper if a pre-emptive method of control is used (be that a herbicide application or a ground preparation) because those weeds which do emerge after pre-emptive spraying are weaker and tend to provide less competition for nutrients, water, sunlight etc., compared to weeds that are left to develop before any action is taken.

Weeding should normally continue until the crop trees become the dominant vegetation on the site, and until the likely level of crop tree suppression or death from weed competition becomes acceptable. Maintaining a 1 m² spot or 1 m wide weed free band around the tree for 3–5 years after planting, is often regarded as the most economically viable measure. Forestry Commission operators thus spray herbicides in three main ways; overall, band and spot spraying.

Overall Spraying

The herbicide is applied over the whole weeding site. Increasingly, the FC uses low drift nozzles and shielded booms to make sure the spray lands on the target surface

Band Spraying

Band spraying (12Kb JPEG)
Band spraying
Spot weeding (14Kb JPEG)
Spot weeding
Spraying with guard to protect trees (12Kb JPEG)
Spraying with guard to protect trees

The herbicide is applied in a band over or between crop trees. These may be non-selective herbicides and in these cases operators are required to take precautions against too much tree contact e.g. by using spray guards. Whilst guards help to reduce the risk of damage, difficulties encountered include extra weight carried and a more cumbersome operation.

Spot Sprayinging

The herbicide is applied as individual spots or over each tree.

In all cases, detailed records are kept of the operation, which includes information of 

  • the product used, 
  • volume rates and 
  • details of the operator. Records may also include
  • plant type, 
  • cover and 
  • weather conditions.

Warning signs are erected to inform the public that a spraying operation is/has taken place. Neighbours are also contacted and buffer zones are marked around those areas not to be sprayed, such as watercourses.

The Forestry Commission requires that sprayer operators are certificated and that their equipment meets all current standards.

The chemical products used are those that have been approved for forestry use and will have undergone extensive evaluation by the manufacturer.

Vehicles used to transport products are equipped with special transport boxes and spill retention kits.