These quotes are from the Gov.uk website

General guidance on using herbicides:

• Follow the manufacturer’s recommendations on using,

diluting and disposing of the herbicide, and cleaning

containers or other equipment afterwards.

• Do not use herbicides when rain is expected, when it is

windy or when the soil is saturated. This is to reduce the risk

of herbicides spreading into or over other parts of the site.

• By law you must take all reasonable precautions to protect

the health of people, animals, wildlife, plants and the

environment. In particular you must take precautions to

avoid polluting water.

• By law you must follow the instructions on the product label

or in the published approval for the pesticide.

• By law you must be trained in using herbicides in a safe,

efficient and humane way.

• You must follow Defra’s Code of Practice for using plant

protection products for England and Wales (January 2006).

You can get this from the Chemicals Regulation Directorate

(CRD) website at www.pesticides.gov.uk