Tag Archives: oxygen weed

Weeding the stream. Again. An ongoing task.

“Believe me, my young friend, there is nothing – absolutely nothing – half so much worth doing as simply messing about in boats.”

Kenneth Grahame, The Wind in the Willows

I misremembered. I felt sure there was a Wind in the Willows quote about messing about in the muddy waters of a stream but I was wrong. Of course they were messing about in a boat, not mud. When I went searching, there were many other charming quotes from the same book which are gently affirming in a world seemingly gone mad, but I found another escape this week.
img_3982I have been weeding the stream. Yes, hand weeding the stream. I see it is five years since I last got down and dirty in the water, although Mark and Lloyd do a certain amount of ongoing maintenance with the long handled rake. I find it easier to climb right in and scoop by hand or sometimes with a rake. It is very muddy and Mark laughs when I stagger back up from the park but I am way too vain (or self conscious, maybe) to immortalise this by taking a selfie of Muddy Me.

There are both eels and fish in the stream – small fish, mostly mud fish – and I find it deeply unnerving when something smooth and slippery brushes past my bare legs. I wouldn’t be quite so anxious were it not for Mark’s recent encounter with an eel. He was reaching into the water to pull out some blockage when an eel mistook his hand for something else and latched on. There was blood, quite a lot of blood and all of it was Mark’s. Eels are renowned for their backward facing teeth so it is not easy to dislodge them, though I think both the eel and Mark got such a fright that everything went flying. I console myself with the thought that eels are not known for aggressive attacks and it would be bad luck for one to follow up with me so soon after. Just in case, I wear both shoes and gloves as a precaution. I am hoping one will not attack my knees, calves or thighs.  Still, as I reviewed one cleaned area of the stream a few hours later, I was disquieted to see an eel gently swimming along the somewhat bare expanse. But it was a small one and I will not be intimidated.

Clockwise from top left: crocosmia, oxygen weed, wretched Cape Pond Weed, blanket weed and tradescantia

Clockwise from top left: crocosmia, oxygen weed, wretched Cape Pond Weed, blanket weed and tradescantia

But the weeds! We get up close and personal with the weeds that are carried down to us from properties further upstream but the major flood in 2015 has caused us a few more problems than before. Crocosmia, often referred to as montbretia but technically crocosmia x crocosmiiflora, have pretty summer flowers but the huge flood carried the corms far and wide and we are now working on restricting its spread. There is simply too much of it for us to be able to eradicate it and we would get reinfested during the next flood event.

Eradication, however, is the aim with the dreaded Wandering Jew (Tradescantia fluminensis). Mark has spent two decades battling this on our properties but still we get new outbreaks washed down to us. The problem is that every piece that is broken off is capable of growing and it is truly rampant once established. Both the tradescantia and the crocosmia grow alongside the water, rather than in it.

The goal is also to eradicate the oxygen weed and the Cape Pond Weed (Aponogetum distachyum). Mark has succeeded once in eradicating oxygen weed so he was most disappointed when he saw a larger form of it getting established on our place. His theory is that it comes from people emptying their little aquariums into fresh water ways, presumably because they do not wish to euthanise their goldfish and can’t find anyone to give them too. Don’t. Please don’t ever do this. Not only do we not need or want free range goldfish in our waterways, the oxygen weed becomes a choking blanket in slow moving fresh water. We have spent countless hours pulling it out but unless we get every bit, it will grow again. Ditto the Cape Pond Weed, about which I have written several times in the past.

What I call the blanket weed – a mass of very fine filaments – is here to stay but we try to keep it from getting too solid and impeding the flow of water. It is at least easy to rake out. Besides, the aquatic life needs some cover.

We are not perfect. Although we try and dead head our waterside irises and primulas, some of those may have washed downstream. I did at least go to a lot of effort to get rid of the noxious flag iris beside and in the water when we realised what an environmental hazard it is in this country.

In the meantime, there are worse ways to spend a pleasant, mild day than poddling about in the water. Our adult son is returning home from overseas next week and plans to stay for a few weeks. He spent many childhood hours playing with his mates in the ponds and the stream  – boogie boarding up and down and playing bike jumping games into the water. I am wondering at what stage I might suggest to him that it would be a huge help to his Aged Parents if he could turn his attention to scooping or raking the weeds from the deepest sections of the ponds which are beyond my reach. We shall see.

We have lowered the water level to enable major weed removal over the next week or two

We have lowered the water level to enable major weed removal over the next week or two

The battle with the water weeds

We have dropped the water level for me to hand scoop the stream

We have dropped the water level for me to hand scoop the stream

I have been getting really down and dirty this week, hand pulling the weed from our main stream. As this involves wading in mud up to my knees, I emerge looking decidedly worse for the wear and no, you are not going to see a photo of me in this state.

Our main issues are with dreaded oxygen weed, Cape Pond weed and blanket weed. If we didn’t stay on top of them, the entire water surface would disappear below vegetation, which rather defeats the purpose of having a stream in the garden. I asked Mark if he thought our problems were related to farm run-off and excessive nitrogen but he is of the opinion that it has more to do with slow water flow rates, though he felt the build up of mud and silt in our streambed would be extremely fertile. When we get sudden bright green algal bloom, it is an indication of nitrogen being applied on farms upstream.

The worst offenders: Cape pond weed and oxygen weed

The worst offenders: Cape pond weed and oxygen weed

There is something very appealing about a natural stream but they are not without their problems. Offhand, I thought of three gardening colleagues with natural streams. One has problems with flooding in torrential rain. The water cannot get away fast enough so it builds up on his property. One has no problem at all with flooding because their stream is in a deep ravine, maybe 20 metres below the level of their land, but this means it isn’t really a significant garden feature. The third has a picturesque mountain brook to die for, bar two factors. Their land has sufficient natural fall to clear flood waters quickly but the bubbling brook can turn into a torrent that scours everything alongside. This means that they can’t have streamside plantings of any quality. They tried two or three times before giving up, having seen the plants ripped out and carried away. Their second issue is that the water is of high purity so a number of neighbours have water rights granted. Each neighbour has installed their own alkathene pipe at the top of our friends’ garden where the stream enters, running the pipes along the streambed until they exit at their adjoining properties down the bottom. There must be at least five alkathene pipes, both black and garish white, visible in that stream. It is not a good look.

So be careful what you wish for. None of these people, however, have to do what we do and clear the waterway of vegetation every year or two. We eliminated problems with flooding and scouring but our water flow is not sufficient to stop the growth of water weed. Our wonderfully natural looking stream is actually the result of outside expertise and in-house experience coming up with a low tech solution. We control the water where it enters our property by means of a simple weir. In normal conditions, this allows the water to flow equally down two streambeds. One meanders pleasantly through our park while the other is a deeper flood channel girded by stop banks. The two stream beds join up again on the other side of our property so the flow downstream is completely unaffected. When heavy rains cause flooding, a mechanism is triggered which directs all the water down the flood channel. By these simple means, we eliminated flooding, boggy patches and scouring from the park though we do have to manually reset the weir in order to get the water flowing again.

The pond weed is the direct result of having a relatively low flow through the park area, though our stream is such that it never dries up. Oxygen weed is a curse. We had a bad infestation which Mark finally eliminated entirely for some years. He blames the reinfestation on people emptying unwanted goldfish bowls into the stream at the corner by the road. Do not ever do this. The goldfish are most likely to die but the oxygen weed is an invasive menace in slow moving water.

Our other great burden comes from a former neighbour who, as far as Mark is concerned, should be lined up and shot for liberating such an invasive weed. African Cape Pondweed, also known as water hawthorn, (botanically Aponogeton distachyum) is undeniably pretty, with a very long flowering season. Presumably this is why the former neighbour planted it on the margins of his ponds. Because he had no control over the water flow, the inevitable floods scoured it all out of his place but it found a lovely home in our slow moving sections. I don’t know how many hundreds of hours we have spent rooting it out. It is quite good friends with the oxygen weed because it can grow through it and spread its lily pad-like leaves. Between them they have the potential to turn our stream to bog. Native weeds are nowhere near as aggressive.

It is only yours truly who has shed most clothes to get in and hand pull the water weeds this year. Generally this is done by the two men in my gardening life (Mark and Lloyd) who take it in turns to wield the long handled rake and manually haul it all out on to the bank. It is a slow process and pretty hard on their backs. I thought it would be faster and easier to do it by getting in and so it is proving to be. The water is pleasantly warm, the mud even more so on sunny days. I just have to time my mud wrestling because I can’t exactly stop for lunch or a cuppa. Wisecracks about eels are not welcome.

Lloyd at least stays cleaner on the end of the rake but it is harder on the back

Lloyd at least stays cleaner on the end of the rake but it is harder on the back

First published in the Waikato Times and reproduced here with their permission.