Using sugar for weed control

[Bluetongue]

Someone sent me this link that I have to pass on, as it's fascinating.

Basically, by adding sugar to weed infested soil (quantities used in the study are specified), the sugar feeds the soil microbes, which use the nutrients and reduce the nitrogen available to nitrogen-hungry weeds... thus suppressing weed growth and allowing indigenous species to regenerate. Ingenious!

http://www.soilfoodweb.com/04_news/docu ... E-zine.pdf

[rev]

yeah watch it with that soil food web mob

Charlatans....

[eataust]

There are nitrogen-hungry natives though, aren't there? I know nitrogen's an interesting issue with plants, but I still haven't quite got a handle on the whole "fixing nitrogen in the roots" deal and all that ...

[Bluetongue]

Sorry EA, I missed your question earlier. I don't know the details of nitrogen requirements of native plants, only the generalities. One reason why nutrient-rich runoff into bushland is a problem is that the conditions favour the exotics over the natives. There must be exceptions, as there is to every other rule.

I'm going to test this sugar thing tho. Our gravel driveway is full of exotic grass and weed seedlings and I need to prepare it for planting to native grasses. I'll try parts in sugar, part in salt. Only using salt because I have some salty water left over from killing a bucketful of snails

[eataust]

You can also just use boiling water, too, I believe; although it probably wouldn't necessarily kill 'em down to the roots ...

[Bluetongue]

On Gardening Australia this week, they gave a recipe for a simple herbicide:

1 cup salt
2 litres white vinegar

It's non-selective, so needs to be carefully applied to weeds only. On the show, they used a wide paintbrush.

[spottedquoll]

Straight vinegar will work (a small handsprayer is good to apply it) and I've found that diluted "Dettol" sprayed onto broadleaf weeds will have them shrivelling up within a couple of hours (especially on a hot day) - though I'm keeping an eye out for a generic substitute as it's an expensive way of doing things (although probably cheaper than the pine oil based herbicides available in handsprays - it smells the same).

[Bluetongue]

Just an update regarding sugar...

The Victorian Landcare and Catchment Management magazine, Autumn 07, Issue 39, has an article on the subject - p10.

A Sweet End to Weeds, by Margrit Beemster

To summarise: researchers at Charles Sturt Uni have been conducting trials and have concluded that sugar is a good short-term weed control method. The rate they used was 500g of refined white sugar per square metre! Repeated every three months. Annual weeds were the ones affected, by the sound of it. 'The researchers are primarily interested in using sugar as a tool to help restore the understorey species in grassy box woodlands'.

For further information you can contact Dr Suzanne Prober at CSIRO or Dr Ian Lunt at CSU (I'm reluctant to subject them to spam by posting their email addresses here, but can pass them on if asked)

[boylesg]

Straight vinegar will work (a small handsprayer is good to apply it) and I've found that diluted "Dettol" sprayed onto broadleaf weeds will have them shrivelling up within a couple of hours (especially on a hot day) - though I'm keeping an eye out for a generic substitute as it's an expensive way of doing things (although probably cheaper than the pine oil based herbicides available in handsprays - it smells the same).

I would be pretty cautious with these remedies (vinegar, salt and detol).

If you put to much vinegar in your soil you will significantly lower the pH, it is an acid after all.

If you use salt over a long enough period and extensively enough then you could potentially render your soils significantly saline.

Who knows what high levels of quarterenry amonium compounds in your soil might do. Are they biodegradable like most of the herbicides are?

[eataust]

Heh. Given how acid my soils are, vinegar would probably _sweeten_ it :)

(I don't really have weeds, apart from serrated tussock which I rip out with the mattock and turn into compost tea for six months+).

[boylesg]

Heh. Given how acid my soils are, vinegar would probably _sweeten_ it

(I don't really have weeds, apart from serrated tussock which I rip out with the mattock and turn into compost tea for six months+).

I think you might be getting your acids and alkalis confused.

If you have acidic soil then vinegar will make it worse. If you have alkaline soil (high pH) then vineger will reduce the pH.

[eataust]

Actually I was making a rather sarcastic comment on acidic soils :)

I scatter a lot of lime and gypsum and dolomite around. It's almost pure clay :)