Reducing herbicide inputs for forest vegetation management

 

Policy

It is UK Government and European Union policy to minimise pesticide use as far as possible. In addition, The UK Woodland Assurance Standard (UKWAS), requires managers to work towards the reduction and elimination of all synthetic chemical use in forestry.

Research

The programme is carrying out research into alternatives to herbicides and where there is currently no suitable alternative, reducing herbicide inputs in forestry.

Alternatives to Herbicides

For many weeding situations, non-chemical options already exist, but they are nearly always dramatically more expensive, as well as being less effective and often less sustainable, than the use of herbicides. However, opportunities exist for investigation into novel forms of non-chemical weeding methods such as biological control (mycoherbicides), use of dye markers, cover crops, mulches and manipulation of planting stock.

Jeskyn’s farm showing young ash trees growing with plastic mulch mats

Reducing herbicide inputs

In some situations there is currently no cost-effective way of controlling invasive, competitive weeds without the use of chemical herbicides.  We are currently conducting a series of experiments to allow us to model critical period of weed competition for various vegetation  / tree interactions. This will allow us to develop practical recommendations for mangers as to how to maximise the impact of any herbicide interventions, for minimum possible input and minimum reduction in survival and growth.

Herbicide reduction trial three years after planting

The photo shows two plots in one of our experiments three years after planting:

• The trees in the extreme left-foreground were only weeded for the first three years after planting
• The trees on the extreme right had just received their first weeding treatment which continued until year 5. 

The photo demonstrates the influence of weed competition on tree form and height; the trees on the right which did not receive early weeding remained 27% shorter than weeded trees after 5 years, despite intensive use of herbicides in years 3, 4 and 5.  This illustrates the importance in terms of both sustainability and economics of planning for correctly targeted early interventions, rather than wasteful and sub optimal later interventions..

Reducing Pesticide Use in Forestry

This major publication summarises the current options for reducing pesticide use in forestry, and provides guidance on minimising risk of damage to the environment should chemical use be necessary.

Details and download...

Summaries from selected scientific papers

• Natural products as herbicides for tree establishment

The above also lists the respective practical implications. See also:

• Forestry Commission publications on reducing herbicide inputs for further practical guidance
• Other scientific publications on vegetation management for a complete list of relevant publications.