The Water Framework Directive is legislation that has been created at the European level and has been approved by all Member States and is currently being implemented by the UK Government. It means that the Environment Agency reviews the impact of all materials on water systems on a catchment basis. A number of herbicides are currently under review to ascertain if they are being found within the water systems.
How does this impact how we control problems in aquatic systems?
Over the last decade a significant proportion of the pesticides that we used and took for granted have lost their approval for use. Within an aquatic system chiefly we relied upon Dichlobenil granules (Embargo G and Casaron G) these would sink to the bottom of the pond and control the plants in situ, however this chemical was found within water that was sampled and therefore, quite correctly, was removed from the list of approved products. However, this does leave us with a problem: there are no chemicals that are approved for use within the UK that can be used to control plants that are submerged within water. There is an important distinction to make here: plants that emerge from the water or are floating on the water can be controlled with the use of Glyphosate with the specific written approval of the Environment Agency.
Therefore the types of weeds that can’t currently be controlled with herbicides are Canadian Pondweed, Elodea Canadensis.
Alternative strategies are required to manage these type of situations. Whereas the type of plants that can be controlled are Water Lillies, Floating Pennywort, Hydrocotyle ranunculoides, Parrot’s Feather, Myriophyllum aquaticum.