Weed Control in a Farm Pond

[Steve King]

Hi - a little off topic, but maybe someone can help.

My brother has moved to a former farm house and there is a farm pond in the garden. The pond is around 30'long, 16' wide, the depth varies all over the place, but it is around 4?' at its deepest point.

The surface is covered with a red leafed plant - it looks a bit like a succulent plant you would have on your rockery. The weed is so dense that there is no water visible!

My brother and I spent around 4 hours scooping out 20 wheelbarrows full of the stuff out. That made a lot of difference - there were several weed free areas and the weed itself was a lot thinner.

A couple of weeks later, the wretched weed has grown back thicker than ever.

As far as we know there are no fish in the pond, but it is rich in newts and dragon fly larvae. We don't want to wreck the ecology of the pond, but we'd like it to look more like a pond and less like a red quagmire!

I'm thinking along the lines of removing more of the weed and then partly draining the pond and refilling with fresh water as I reckon the water must be full of nutrients.

Any ideas anyone??

 

[jason fisher]

I'm thinking along the lines of removing more of the weed and then partly draining the pond and refilling with fresh water as I reckon the water must be full of nutrients.



first idea good, second part no don't not ever at anytime, leave it to the rain, anything else and algae will go mad.
have you got a photo of the plant, i'm curious it could be one which is pretty rare.

 

[Steve King]

I don't have a photo of the plant, but I'll have a scout around on the net and see if I can identify it.

 

[Wolfman Woody]

Yes, Steve, don't put tap water in. You'll bugger it completely. It'll probably go green.

Is the leaf furry and spongy?

 

[The Digital Monkey]

Spray it with round-up.

 

[Joskin]

There is some kind of weed killer available that you can put in the water that will not harm the other pond life that you have. I am not sure what it is called or where it can be obtained but I could find out for you if it would be of help to you

 

[The Monk]

Steve this may not be practical but weed is fed by light, if you can put a large black plastic sheet over the top of the pond the weed will died off. It sounds as if the land is in the process of reclaiming it, basically thats what happens to a pond if its left long enough of course. In the old days they use to use Raglon, but it created all sort of ecological problems, just try blanking one area off at a time and see what happens, you also need to check out what the substrate material consistancy make up is, a rich soil substrate could attract the wrong type of plants, isthe pond in shade or in the open?

 

[Herr General Swordsy]

the plant sounds like the floating American fern thingy thats recently been banned because it is so invasive, sorry cannot think of its name but stick to the physical removal of weed, i know its hard but think of all those little newts and dragon flies.

if you were to introduce some fish think about pur blood crucians, it sounds ideal for a small group

 

[The Digital Monkey]

there is an aqutic weed spray dont no where to get it from but you need to be licenced to obtain it and use it.If you can do like the monk says and cover it it will kill of the weed.Some weeds the more you rake out the more they grow back.Or you can take the more exspensive way and hire a drott to dreadge it.

 

[Steve King]

Thanks for the replies guys.

I've had no luck identifying the offending plant/weed on the net. If anyone has an idea of the culprit please email me (preferably with a pic). I'll also see if my brother is able to take a digital picture opf the weed so I can send it to you.

The plant floats is mainly green if you look at it by itself, but the leaves have red bits which make the whole pond look red when you see it.

Nick, the pond is perhaps a little too big to block out the light. The pond is in the open, but the East side has a little shade. The substrate is pure clay. We reckon the pond was formed by quarrying for the clay to make the bricks from which part of the house is built from.

Jeff, the leaves are not really furry, as I say it looks a bit like a succulent, but with a few roots dangling.

If its of any use, the previous owner of the house says that the pond used to have a bit of duck weed and silk weed previously = the red stuff suddenly apeared a few years ago.

 

[Phil Hackett 2]

Steve I suspect from the description you give, the plant is one of three species.

Azolla filiculoides (Water Fern), Azolla caroliniana (Carolina Water Fern) both originate from the US, now banned from sale, or Spriodela polyrhiza (Greater Duckweed).

As we?ve got on a subject that concerns me greatly (non-indigenous water weeds and marginal plants), and I know we have a few pond lovers on here, I?ll offer some free advice. Whether you want it or not!

When looking at making a pond or refurbishing one, leave the non-natives in the garden centres and only use the native species. Many of the species that have been sold down the years by garden centres have got out into the wild, wreaking havoc on the receiving water bodies. Azolla & Canadian pondweed are just two, but the most invasive is Cressula helmsii, known as New Zealand and/or Australian Water Stonecrop. This stuff is so invasive it can cover a water in two years down to a depth of 10 ft. Just one small broke off piece can start a complete new colony, which will ultimately cover a medium size lake in the time period.

There is as yet no effective practical control for it, and it will withstand long periods of freezing and desiccation. It?s the yob of the weed world, killing all other submerged native weeds by blocking the light from them and robbing them of any nutrients. It?s now banned from sale in garden centres, but many of them probably have spores in their ornamental ponds just waiting for the right conditions to explode, and your new pond is most likely to be just right for it.

When buying weed or plants ask where they come from, and if they ain?t native don?t buy them and tell them why you won?t buy them. The Govt. is too slow to stop this trade in non-indigenous weeds and plants and only consumer pressure on the garden centres will stop them selling such wretched stuff.

I?d go with what the Monk says here Steve about black plastic covering it. You can probably get it off a local dairy farmer for nothing, as silage come wrapped in the stuff, and he throws it away after unwrapping the huge bails. Each strip is 10ft wide by 20 ft long, so there should be enough to cove the pond from 3-4 bails.

 

[Steve King]

Thanks for that Phil, Azolla filiculoides, it is!

I have a chat with my brother and pass on your suggestions.

 

[ED (The ORIGINAL and REAL one)]

You may find this interesting:

WEED CONTROL

 

[Wolfman Woody]

This it here then Steve?

My question "Is the leaf furry and spongy?" meant what you said in fact. I believe the hairs are spores, but they're so very small you'd hardly notice them. Sod to get rid of.

I'll ask my EA pals, sometimes you can use Glyphosate (Roundup and, I think, Pathclear) on pond weeds without any problems to other life. So long at the leaves are on the surface it will kill them and the roots, but in the water it's relatively harmless.

Might be better though, if you can get enough out and just after winter, to put some fast growing natural (Nymphaea alba) lilies in. That'll deny them sunlight.

 

[Fishing Gimp]

Probably the safest way to cut down the weed is to keep hauling it out for a period of time and hope it will give up eventually. If you use any plant killer it will have some hitherto unthought of side effect on the indigenous fauna - it always does! The other thing is what type of newts inhabit the pond? The reason i ask is because if they are Great Crested Newts and you alter their habitat significantly you could find yourselves facing a fine and the undying hatred of any local wildlife trusts!
Be careful as these people have more influence than most of us realise until you cross them.

 

[ED (The ORIGINAL and REAL one)]

There is only one way to eradicate it completely--- Guaranteed!!!!--
It will cost you ?95
See here:


AZOLLA CONTROL

 

[Steve King]

Hmm interesting Ed! That could save us hours of work. Standing up to your waist in water for hours scooping out weed is pretty hard going!

I think the environment will change for the better if native plants are introduced, the newts will thrive I reckon...

 

[jason fisher]

killing weed doesn't work.
all it does is puts a load of rotting vegetation into the water, this gives off loads of nitrates which feed algae then you get pea soup.
removing the weed and placing it away from the water on a compost heap till it rots right down provides you with a good source of said fertiliser and removes the nutrients from the system thus starving the algae.

 

[jason fisher]

the other problem we have here is jeffs sugestion of introducing nymphaea alba, it's a lovely lilly but it's roots will be through the bottom of a clay based pond in no time leaving you with a leak as will any of the reed mace varieties.
one none native which i would encourage is hottonia pallustris the water hyacinth, it is south african but it's not that invasive and the dragon flies and damsels love it, the other thing is it never seems to stop flowering which provides you with lots of baby plants. which are easy to remove if you don't want it to spread.

 

[Steve King]

It certainly makes good compost Jason! The compost heap has been steaming since we dumped 20 barrow loads of Azolla filiculoides on it!!

I doubt if nymphaea alba would cause a problem with the pond, my brother lives in Sussex and the clay is pretty thick.