Aquatic Weed Control:
There are a number of aquatic invasive species, including Floating Pennywort, Parrot's feather etc and details of their optimum control can be found here.
Japanese Knotweed Control
Japanese Knotweed is a controlled plant in the Wildlife and Countryside Act and the Countryside and Rights of Way Act. It is an offence to cause it to grow in the wild. This means that you must exercise Duty of Care when handling or transporting material containing Japanese Knotweed.
There are three methods of controlling Japanese Knotweed, mechanical or chemical and biological
Mechanical control - this is digging out the rhizomes from the contaminated area and sending them to a licensed disposal facility. This is expensive. Sieving the soil on site and burning the sieved rhizomes is a better option, but still involves massive disturbance of the soil.
Chemical Control - Japanese Knotweed is easily controlled by applications of the right herbicide at the right time of year.
Glyphosate - Approved glyphosate formulations is usually applied near water. Better control is achieved using the adjuvant TopFilm. Stem injection of glyphosate is better in mixed vegetation, and where only small stem numbers are present
Picloram - should only be applied away from water, but gives very good control. Weed wiping young growth works where sensitive vegetation is present.