Tag Archives: water weeds

Dispensing with the big pond

Everything grows so quickly. Back in the 1990s, the whole area was much more open

The big pond is a good example of how conditions can change over time. Sometimes decisions need to be made rather than fighting nature to try and preserve an increasingly unsatisfactory status quo.

The pond had ceased to have a function. Originally, it was our swimming pond where we used to gather as a family for summer dips. That stopped when we built a swimming pool which didn’t carry the perils of resident eels.

Our son Theo used it in his middle childhood. He and his mates built a bike jump and it became a show of macho youthfulness to see how high up the hill they could start their run with an old pushbike. The aim was to build up as much speed as possible, hit the launch pad and part company from the bike in mid-air, both boy and bike landing separately in the deepest part of the pond. It was the responsibility of the rider to dive to retrieve the bike and get it back to shore. It sounds dangerous and maybe it wasn’t the safest of childhood pursuits but there were no major injuries.

By last spring, the water had all but disappeared from view

Over time, the weed infestation took hold – possibly because of increased nutrient loading in the water from upstream farming activities. It was several years ago that I figured that it was unwise to get into the water when I had open skin wounds, even just minor abrasions. It only took a few hours for fungal infections to start getting a hold. It is not water that I would swim in these days.

With the growth of weed, we lost any reflective qualities of the water.

It was only three years ago that Theo did a major clean out for us.

Three years ago, Theo was at home for a couple of weeks, en route from Amsterdam to Melbourne. He did a trojan job clearing the pond of accumulated weed but short of finding somebody willing to do that every year – volunteers are not so much thin on the ground as entirely absent – we needed to concentrate the flow of the river into a designated channel and abandon the pond.

The platforms that enabled Lloyd to reach the middle of the pond

I missed the photo of Lloyd walking on water. By last Monday, he had reached the point where the pond narrowed sufficiently for him to stretch from the banks. We have an extra-long handled rake and have put a long handle on the drainage fork. All I can show you are the platforms he was using made from corrugated iron, linked by wide wooden boards. The principle is of spreading the weight so the human on top does not slowly sink into the morass of water weed and silt. With the water level dropped as low as we can get it, the silt layer is still about a metre of soft, floating soil particles. With resident eels. Lloyd hauled all the weed to the sides of the pond and has basically created terraces which will compact and solidify over time, leaving a winding channel in the middle.

Lloyd hauling out large swathes of Lousiana iris 

The wakendorfia have all been removed this week and the oxygen weed raked out of the smaller, upper pond.

At the same time, he and I removed 2/3 of the Louisiana iris (ratio of foliage to flower is much too high to justify massive swathes of them). I dug out the remaining Wachendorfia thyrsiflora. It is showy in bloom but too invasive and free-seeding to keep by running water. We try to manage what we may be spreading downstream. I took a rubbish bag down with me to load all the bulbs of the weedy montbretia (Crocosmia x crocosmiiflora) and all the bits of Tradescantia fluminensis  – both invasive weeds that repeated floods keep delivering us from upstream. Readers may know the tradescantia by its common name of ‘Wandering Jew’, or maybe ‘Wandering Willie’. We have decided that the Jew epithet is nothing short of downright offensive and Willie carries other connotations so we have trained ourselves to refer to it as ‘Wandering Trad’. Let’s lay the responsibility for this plant where it belongs – which is presumably with plant collector, John Tradescant, not with the Jews in the millennia when they lacked a homeland.

We have reached this stage of narrowing the pond to just a stream channel. The water is very low at the moment because of unusually dry conditions

There is still a clean-up to be done around the stream but fortunately, we are in high summer and it is dry. All the plant material is being left out to be dried by the sun and we will then stow it beneath established trees and shrubs where it can rot down. It has to be dried out so that it doesn’t take root and grow again. The mud and silt will be raked out along the sides where necessary. And we will let the grass grow long again. I am hoping the result of some pretty solid work across the past couple of weeks will be a greatly improved meadow display this coming spring and water that is more bubbling brook than sluggish stream morphing into swamp.

The big lesson we have learned from this is that we need to do more to control the growth on the banks of the stream, not by stripping them bare or spraying but by strimming them twice a year when the park gets mowed. It is all part of the learning process on how to manage a more natural-style of gardening.

A last resort – getting in a digger

I have commented before that water in the garden can involve quite a bit of work, be it still water, treated water or running water. And water has had us busy this week.

The mill wheel bird bath can become a breeding ground for mosquitoes in summer

We have treated water – a swimming pool. Once that is up and running for the season, it doesn’t take much to keep it clean because we have a salt filter on a timer. We have still water – two pond features with goldfish and an historic mill wheel which serves as a bird bath. The problem with the mill wheel is that, without fish in it, the mosquitoes breed up within about three days so we have to drain it and replace the water often over summer. True, mosquitoes breed up anywhere there is still water, even in the bromeliads (and we have quite a few of those). But the mill wheel is close to our bedroom window so I blame that for the incursions of nasty, blood sucking critters in the night.

I cleaned out the excessive growth of the aquatic plants in the sunken garden this week. Goldfish stop this from being infested with mosquito larvae.

The goldfish ponds are relatively easy care. I go thorough a couple of times a year to scoop out the build-up of rotting detritus and to restrict the growth of the aquatic plants and we have to top them up with water in dry spells. The pond at the bottom of the sunken garden is too shallow so it evaporates quickly and we often get algae spreading that needs scooping out with a sieve but it is all pretty straightforward.

A last resort – Lloyd on the digger. You can see the mat of grass that had established on the choking silt.

Running water – the stream in the park – is nowhere near as simple to maintain. This week, we admitted defeat and hired a digger. We haven’t put a digger through the stream for about 25 years and it is an absolute last resort because it destroys the entire eco-system. Generally, we can get away with going through with a long-handled rake and drainage fork every couple of years to haul out the excessive growth of choking weeds – back breaking work but kinder to the environment. This time it was beyond that and the issue was the excessive build up of silt. We were at the point where the stream was turning into a swamp with little water movement.

There were four reasons for this state of affairs and only one of those was caused by our management. The water that flows looks clean enough to the naked eye. As Mark observed, it is a good example of how a visual assessment is not an accurate guide to water quality. Because it flows through farmland upstream, the silt loading is high. It runs dirty every time it rains and and over the years, the silt dumped on our stretch had built up. It also carries a very high nutrient loading from farm runoff and that means we are battling water weeds all the time. Then when the culvert at the corner was replaced last summer, it involved earth works on our place and the soil was not compacted so there was a major collapse during a flood. That reduced the water flow through the park by at least 50% with the water going over the weir and down the flood channel instead. Digging out that silt bank blocking the stream was too big a job to do by hand.

Neither Mark nor I were game to try driving the digger but fortunately Lloyd is not afraid of machinery though cautious by nature.

The fourth problem was of our making. When we decided to manage the park as a meadow and reduce mowing to just twice a year, we also stopped strimming the banks of the stream. With the build-up of silt and the greatly reduced water flow, the grass had invaded the river and formed a mat that was too heavy to dig out by hand. Hence the digger. We can’t get a big digger in because of access restrictions and the placement of many trees and shrubs so Lloyd spent two days quietly and cautiously working his way round the areas that could be accessed safely from the cab of the little digger. Its reach is not long enough to scoop the two ponds we have so they remain an unresolved issue at this stage. We are thinking we want to create a channel for the water and turn the ponds into bog gardens but the details of how we manage that transition are not quite clear yet. Natural ponds are even harder to maintain than the stream and we think it is time to draw the line beneath having those.

Mark will probably plant trees to shade more of the stream. When water is shaded, it stops the rampant growth of choking water weeds and it is much easier to stand on the bank and rake out what is there.

This was just a small eel that appeared a little disoriented at finding itself on dry land. I helped it find the water again.

I have a vested interest in this. I have found that it is easier to weed the stream by dropping the level (which we can do with the weir and the flood channel) and getting in the water to clear it. It is a very muddy procedure but easier on my back than doing it from the bank. I started doing this last week before we decided to get the digger. I cleared one stretch of several metres but I can never get in that water again. The next day, I was back again, this time raking from the bank just down from that area I had cleared. And lo, there was a very large eel undulating through the shallow water. I am always aware of my tendency to hyperbole so I didn’t want to exaggerate its size but Lloyd spotted it sunning itself the next day and estimated it to be about 80cm or more in length with a girth behind its head of close to 50cm in circumference. I knew we had eels. I had to head one in the right direction to get back in the stream and I have seen many small ones. But that is too large an eel for me and there may well be more than one of them that size. I am scared of eels.

The aim is to manage the stream without needing to resort to a digger again – at least in our lifetime.

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

Flagging away the flag iris

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The first time I realised there was a problem with our flag irises was when Mark intervened to pull a photo from a House and Garden feature on our garden a few years ago. It was a view similar to that above. “It’s a weed,” he said. “It is embarrassing to be shown with a weed.” It has taken a while, but this week, I have dug out the last of it.

The offending flag iris

The offending flag iris

The problem with Iris pseudacorus is its resilient and invasive ways. It can survive in water, even in salt water, beside water, on water as a floating mat of rhizomes and even just on heavy soils and flood-prone areas. It is also poisonous to both humans and stock so is not controlled by animals. It is on most New Zealand weed lists and some regional councils require active management to control its spread.

Behold the offending rhizomes

Behold the offending rhizomes

Our flag irises have never set much seed, though all the descriptions say that seeding is a problem. We would have acted faster, had we seen threatening seed set. But the rhizomes, the rhizomes! They are sign enough of an issue. They form a dense mat both on and just under the surface. It reminded me of digging out wild ginger with their ability to form a solid barrier, choking out other growth. It was heavy, muddy work digging them out and prising stray rhizomes from farthest reaches with me, precariously balanced. I did not want to end up in the stream at this time of the year.

We had them planted by running water; the upper reaches of the Waiau Stream flows through our park. It was clear that floods or any disturbance of the rhizomes could cause some to wash downstream and from there, populate the countryside. It would not have been an issue had they been by a self-contained pond with no means of escape.

True, we grow Primula helodoxa and that is sometimes flagged as a weed issue by waterways but we dead head it. It is the seeding that is problematic with that plant.

Iris sibirica

Iris sibirica

Lovely Higo irises

Lovely Higo irises

and Louisiana iris

and Louisiana iris

Fortunately there are alternatives to the flag iris which do not seem to be a weed problem and are arguably considerably prettier.  Iris sibirica, the Higos and the Louisianas are all happy in similar conditions and give us a League of Nations in our park – Northern Europe and Siberia, Japan and USA. We just happened to have plants of all hanging about waiting to be planted. So while the three patches of flag irises are now muddy and apparently bare, in a few months’ time, they may even be flowering again in hues other than yellow.

036We are enjoying the water meadow effect we are achieving in that area of the garden.

More Louisianas that Mark has been raising to plant out

More Louisianas that Mark has been raising to plant out