floating pennywort..

parts of the Colne here have been infested with this stuff for the last few years, huge clumps of it above fallen trees and any other slack water.
Apart from donning waders and manually ripping it out , anyone know how to eradicate the stuff without chemicals?

Simon

This stuff is very hard to get rid of. I've heard the only surefire way is to drag it out and burn it....every last bit and be prepared to have to repeat that ad infinitum. The trouble is any bits that float off will probably root elsewhere. The Colne has a major problem with this stuff and I can only see it getting worse & worse.

Skippy

As i understand it, when you pull this stuff out you help spread it. Like Skippy said, you will have to keep doing the work time and time again.

Sorry to say it, but Chemicals may be the only way.

If you can get anybody interested in trying to tackle it...which I doubt. On one of the rivers in Wales I fish for sea trout they've been trying to get rid of the infamous Himalayan Balsam. You have to spray this stuff at just the right time 3 years in a row simply to stop the stuff spreading and only then can you start to think about eradicating it. This is year 4 and its still not sorted.

Like many things[ cormorant,signal crays,pennywort etc]...by the time you realise you have a problem its probably too late to do anything about it.

What we need is to introduce something that feeds on pennywort,crays,mitten crabs & cormorant that turns into a shoal of roach when it reaches maturity.

Fortunately we do not have a problem with my ‘ticket’ stretch of the Colne... YET.
The problems appears to some stretches to be quite severe, including the formation of dense rafts reducing light levels below the rafts, deoxygenating water killing fish and other fauna and blockages which may lead to flooding. It appears that herbicides are the most, if not the only, effective method of control if administered at the right time, i.e at the end of the growing season.

Does this stuff have a growing season ? It seems to be there all year and is bank to bank in places.Chemicals are dangerous things....look whats happened at Farlows.

Just had my ticket and latest news from GXUDS and they're asking members to remove it from the Colne.

Some of the chemicals are faily safe, such as glyphosate, as you need to spray it onto dry leaves. As soon as it touches the water it is so diluted it causes no further harm, or so I was told.

I believe that maximum growth occurs in late summer and it over-winters on banks as a much smaller and flatter plant. Apart from that I’m not that knowlegable, however I’ve managed to find this information which may be of use.

‘Persistence and Spread: Floating Pennywort can double its weight in as little as 3 days. In Britain the plant exhibits seasonal growth.
New plants: Vegetative reproduction in Britain, and can form extensive mats from the smallest shoot fragment.
Management: Control is extremely difficult to control due to rapid growth rates but can be achieved using tailor-made treatment programs carried out by a specialist company.
Chemical control: can use glyphosphate or 2,4-D amine but plant does not rot down very quickly after treatment so vegetation should be removed after 2-3 weeks in flood risk areas. Regular treatment necessary throughout the growing season.
Regular cutting from May-October will prevent complete dominance. Cut material needs to be removed from the water immediately. Hand pulling or spot chemical treatment should follow cutting to reduce re-growth. Pulling can work well on small infestations’.

Here's the DEFRA cribsheet on it
https://secure.fera.defra.gov.uk/.../downloadDocument.cfm?id=31