Re: Convolvulus arvensis -- oh lucky day!

Susannah wrote:
> At 09:11 PM 12/30/03 +1300, Tony and Moira Ryan wrote:
>
>> Actually there is one which is effective and that it Dicamba (which
>> has been sold here as Woody Weedkiller). On certainly needs to be
>> pretty careful with it though as it will kill just about anything else
>> as well. The safest way to use it is to unwind shoots and immerse the
>> tips in a bottle or can containing a solution of it. This must be
>> arranged so it cannot fall over and spill the stuff on the ground. In
>> a few days it will translocate into the root and kill it. I have also
>> seen someone succeed with a double strength Roundup solution use in a
>> similar manner.
>
>
> I'm not sure I understand this correctly -- do you mean that you have
> one can per shoot (or cluster of shoots within reach), and that you dip
> them in the can leave them in the can overnight? I think I would need
> thousands, or maybe tens of thousands of cans! Or do you just dip them
> in for a second or two?

Actually, I had not really thought of using this technique except for
mopping-up operation or among desirable plants which cannot be easily
removed first. I am not quite sure how long it takes to act and have usually left it at least 3 or 4 days, but quite possibly a few hours is all it really needs.

Both Dicamba and extra-strong Roundup will work very effectively if
sprayed generally over a patch such as you have, but nobody dedicated to organic growing could countenance this use, which can have direful effects on the ground and it's valuable inhabitants and at least with Dicamba anything you might plant in it for some time after.

>> just one other possibility. If your climate is suitable and there are
>> no valuable plants in the area what about trying soil sterilization by
>> insolation next summer?

> Is that different from covering with plastic? I had thought they were
> different words for the same thing.

Yes, It _is_ different from a black plastic mulch, which is not intended to sterilize the soil, as it will after all allow things like strawberry or tomato roots to grow under it successfully, but is only really effective in a climate with a sufficiently hot summer(I find in my garden where summer temps rarely even reach above 75 degrees F it is pretty useless). To begin with, one uses a _clear_ plastic film which contrary to popular wisdom heats the soil up much more than the black. Then one prepares the bed by loosening the surface soil thoroughly followed by watering copiously before applying the plastic and sealing the edges as far as possible by burying them.

What one then has in effect is a steam sterilization apparatus which
will continue to operate to a gradually diminishing extent until
the heat goes out of the soil or the plastic seal is broken. If I
remember rightly a covered period of about six weeks is suggested.

This is mainly use to counteract soil borne diseases and kill weed
seeds, but as you can imagine it kills off much of the soil life generally, the good organisms as well as the bad. However, a good many of the desirable microorganisms are capable of surviving in protective cysts through all the cooking and will come out of hibernation successfully once things cool down again, while most disease organisms are not so sturdy. To replace the rest of the "microherd" one would then expect to have enliven the soil further over a couple of seasons by several applications of good active compost accompanied by an organic protective mulch.

How much of the Convolvulus it would actually kill though would relate directly to how deep down the effect goes and this I can't help with I am afraid.
>
> I saw a reference to vinegar, too, when I did a Google search. Like
> your experience, it was an unconfirmed rumor, but might be worth a try.

We are lucky here to have the organic weedkiller I mentioned based on Pine oil. It goes under the name of Interceptor, but I have no information as to whether it is only sold locally or on a wider scale. While apparently kind on the soil it is quickly lethal to any aboveground vegetation and seems more effective than just the straight vinegar which I formerly used, but is not so I understand actually translocated much below the soil surface, so like the vinegar it probably works mostly by progressively weakening the growth rather than immediately disposing of the whole plant.

There does seem to be further organically-acceptable solution which I didn't know about previously which was suggested by Jon Stewart and that is to put the area down to grass for two or three years. Even if some of the rhizomes survived this they might well be few enough just to spot treat in the way I suggested..This sounds spot-on to me provided it works and you can afford to do without that whole patch for the requisite length of time. It would certainly be much cheaper and less drastic than most of the other solutions which have been suggested and will leave you with soil in lovely condition for immediate planting.

I don't know if you are aware of the most satisfactory we of preparing garden beds from turf, but the best one I know is to put a smothering layer of newspaper over the grass (about ten sheets thick works well) and then cover this with a thick layer of organic mulch with or without a thin layer of good compost beneath on top of the paper. By the time this surface application has broken down (Several summer months is usually sufficient) all the turf will be dead leaving you with a beautiful, fully organic soil from the decay of both the tops and roots of the grasses plus the top dressing.

Good luck to you whatever course you finally decide on!

Moira

--
Tony & Moira Ryan,
Wainuiomata, North Island, NZ. Pictures of our garden at:-
http://mywebpages.comcast.net/cherie1/Garden/TonyandMoira/index.htm


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