Tag Archives: New Zealand Pigmyweed

Warning: highly invasive aquatic plant, New Zealand pigmyweed, found on the Wandle

There has never been a more important time for every user on the River Wandle to Check, Clean, Dry – we have discovered New Zealand pigmyweed on the Wandle!

New Zealand pigmyweed, Crassula helmsii, is a highly invasive aquatic plant introduced to the UK in the 1900s as an ornamental “oxygenating plant” for ponds. It is thought to have escaped to the wild naturally (transported by wildfowl moving between ponds) or as ponds/aquaria were emptied out into nearby rivers.

Where would we find it?

New Zeland pigmyweed grows in still water, such as ponds or lakes, and also in slow moving waters like canals. It can even form dense colonies on damp mud and could therefore colonise marginal and impounded areas of the Wandle, and many of the backwater habitats.

Where is it in on the Wandle?

Currently, the only known New Zealand pigmyweed colony is in a small pond in Hackbridge / Beddington where it was discovered during our recent Wandle cleanup, highlighted on the map below.

Why is it bad?

New Zealand pigmyweed forms dense mats on the surface of the water, and up to 3 m under the water. These mats can shade out other plants below, resulting in a decline in oxygen in the water which has negative effects on invertebrates, frogs, newts and fish.

Much like floating pennywort, New Zealand pigmyweed can hinder recreational activities such as angling, by creating impenetrable “carpets” across open water bodies.

Finally, the control and eradication of this plant is very difficult. We are unlucky to have it, but lucky that we have discovered it with only one colony! In many other catchments where it has become established, water seems to have disappeared from the landscape.

Manchester Airport Pond, Photo Credit: Paul Breslin

What can I do to help stop the spread?

Avoid the pond! The pond where we have discovered the plant is not currently used for recreational purposes and ideally this would remain the case. For example, if you walk dogs in the area, please make sure they don’t go for a dip in this pond, as they could easily then transport it to wherever they next go for a swim. The plant can grow from tiny fragments that you might not even spot, so it is better to be safe than sorry!

Be vigilant! We believe (and hope!) this is the only case of New Zealand pigmyweed on the Wandle. However if you are out and about and believe you see the plant, please get in touch with us so we can come and investigate. You can call Polly on 07833 497 599 or email her at polly.bryant@wandletrust.org

Check, Clean, Dry! Finally if you are an angler on the river, or a use the river in another way such as canoeing, please make sure you are following biosecurity procedures such as Check, Clean, Dry. This will not only help reduce the risk of spread of New Zealand pigmyweed, but also the spread of other INNS and potential new INNS to the Wandle from other rivers.

Wandle cleanup: May 2017: Beddington Park

The one with a Limerick…

Did you know last week was National Limerick Day? Well, if you didn’t, to get this blog started here is a Wandle limerick just for you:

But on with the cleanup…

As May is the start of Himalayan balsam season, our cleanup for the month focused on Beddington Park, with our usual volunteers joining forces with our Invasive Non-Native Species (INNS) teams: the River Rangers and the Hit Squad.

On the Wandle, Himalayan balsam is widespread and is not great news for the river. As part of our Wandle Invasive Species Project, we have been working with our River Rangers and Hit Squad to map the distribution of the plant on the river, and plan out action to work towards its eventual eradication.

Beddington Park, and Richmond Green just upstream, are considered the “source” of Himalayan Balsam for the Wandle, sending seeds downstream to colonise new sites, and are therefore priority areas to target.

On a sunny Sunday morning we were joined by 58 volunteers, including a local scouts group and our INNS Officer, Alan, with his trusty sidekick, Pepper the dog. After our Health & Safety briefing, we divided into two teams to get started: the cleanup crew and the balsam bashers.

Alan led the balsam bashers. Having worked on the site last year, Alan knew where the balsam would be and took a team of volunteers to remove every single plant.

Meanwhile, the cleanup crew got started on the river. The waders headed upstream from Church Lane towards Richmond Green and it wasn’t long until two trolleys were found.

And then not much longer until another two were discovered!

While working up the river, the cleanup crew kept an eye out for any Himalayan balsam growing on the banks of the Wandle, removing each plant as it was discovered.

In no time, we had made it to the weir and started emptying the trugs of rubbish into wheelbarrows.

Andy and Dave then led an “expert” team over the weir all the way to Beddington Lane to clean and check for balsam on a stretch we are usually unable to access.

We still had 40 minutes until lunch, so the rest of us headed back to the tent, got back in the Wandle and headed the other way to clean the river inside the park. It was close to spotless with only the odd can or bottle!

By lunchtime, the balsam team had finished, and the cleanup crew were in need of a drink. We all gathered back at the tent to have lunch and enjoy the sunshine.

After a longer lunch than usual, Alan took the Hit Squad (our team of volunteers trained in the management of Invasive Non-Native Species) to the small pond on London Road, just outside Beddington Park. Here there was some floating pennywort to remove as part of the Wandle-wide battle against the very invasive aquatic species. A rather terrifying discovery however, was the presence of New Zealand pigmyweed (Crassula helmsii) in the pond as well – photographs and samples were taken to confirm but this aquatic plant could cause real problems for the Wandle.

Photo Credit: GBNNSS

The rest of the waders got back in the Wandle and finished off the last 100 m in the park, finding an extra 3 or 4 bags of rubbish.

It was then time to check the skip was packed, and the van, and then all head home for a nice cold beverage.

So what did we find?  1 washing line complete with pegs, 1 car wheel clamp, 1 tow bar, 1 buoy ring, 1 bag of lemons, 1 coffee table, 1 football, 1 tennis ball, 1 cricket ball, 2 traffic cones, 3 coconuts, 4 trolleys and 15 other bags of rubbish, plus around 200 balsam plants.

Huge thanks to local volunteer Jackie for kindly funding this event, Sutton Council for purchasing some much needed litter pickers for us, everyone who helped unpack and pack up the van during the event, Rosie for supervising the Event Tent, Rosie and Alan for helping me back at the garage, Ann for baking some treats, and the Parks Team at Sutton Council for organising collection of all the rubbish the next day.

Thank you to all our volunteers for coming:   Aaron, Aenes, Alex, Andrea, Andy, Andy B, Ann, Cain, Caroline, Charles, Charlie, Chris, Claire, Clare, Dave, David H, David S, Derek, Drew, Ed, Gavin, Geoff, George, Gillian, Guy, Jackie, Jane, Jenny, Jessica, Jim, John L, John N, John S, Joshua, Justyna, Katrina, Ken, Kilian, Kim, Matilda, Michael, Nick, Nicola, Olivia, Per, Phil, Rolanas, Rosie, Sheila, Sophie C, Sophie N, Steve, Talus, Victor, Wally and William.

So what did I learn from this month’s cleanup? The difference between coconut water and coconut milk!