Alternative weedkillers

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Marilyn

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Alternative weedkillers
« on: July 26, 2012, 11:53:43 am »
Hi all,

I have been running the garden basically organically for the last two and a half years - with excellent results for biodiversity. In terms of insect pests, I have found that a little patience pays dividends - for example, waiting a few weeks while controlling an aphid population by hand removal normally sees some ladybirds move in and take care of the problem. However, I am finally facing the fact that I must consider alternatives for certain problems, notably invasive grasses and the dreaded Cyperus rotundus. We have been hand-pulling these so far, but it is an uphill struggle to keep on top of, and a huge drain on manpower which could be much better employed in more constructive tasks.

I have been doing a bit of online research and there is a LOT of discussion about the ill effects, or lack thereof, of glyphosate, not to mention other weedkillers. I re-read the thread on this forum about spot application of glyphosate and this still seems to me like the most sensible approach. I am curious to know, however, if there is a chance of the chemical moving into the soil from the plant matter, once it has died back.

I am also curious, as the topic title suggests, to know about any alternatives that you good folk use. I am increasingly wary of these "home cures"; quite often one finds people talking joyously about some household product they have discovered is a marvel for killing the weeds and an alternative to "Evil Chemicals", but in fact is far more toxic than an adequate herbicide would be, in the untested dose they are using. I am reminded of the day we were talking about glyphosate in college, where I discovered that the lethal dose for caffiene is much lower than that of the "Evil Chemical", i.e. caffiene is by far the stronger poison.

I have heard about vinegar but it strikes me that this could have quite noticeable effects on soil acidity and composition, and salt - which will certainly be a disaster for the soil chemistry if applied over any length of time. Similarly the "boiling water" cure is often touted, but I presume this will scorch one's top growth at best, leaving the plant to regrow from the roots after a time.

So, ladies and gentlemen of the forum, what are your thoughts?
I work in hotel and private gardens, promoting sustainable landscape management in the mediterranean climate through the use of diverse, beautiful and appropriate plants. At home, I garden on two balconies containing mostly succulents.

Joanna Savage

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Re: Alternative weedkillers
« Reply #1 on: July 26, 2012, 02:52:26 pm »
Hello Marilyn, when I was a student in the Dept Agriculture, University of Queensland, before the introduction of glyphosate, our Agronomy lecturer, Dr Percy Skerman advised us about the control of nutgrass 'Cyperus rotundus'. He said the most certain means of control was to build a 'chook yard' over the offending patch. That is the Queensland way of saying 'build a hen run' over the infestation. The hens eat every emerging shoot of green as soon as it appears. I don't remember how long they would take to do the job, but judging by the persistence of the underground nuts, repeated spot applications of glyphosate might be faster. Joanna