Hi go through the following
1. USDA research indicated that at low concentrations acetic acid had variable success in controlling weeds, and then any success was only when the acetic acid was applied to young weed seedlings (less than two weeks after germination). I had used kitchen vinegar with a concentration of 5% acetic acid on mature plants. To kill adult weeds, the concentration of acetic acid needed to be much higher. At higher concentrations, the results indicated that 85-100 percent of the weeds treated were killed. This has not been tried on all weed species.
Source:
Vinegar as herbicide
2. cetic acid is what makes vinegar a weed killer. Actually, it makes vinegar a plant killer. Acetic acid, from any source, will kill most vegetation because it draws all the moisture out of the leaf.
It is fast. Spraying full strength vinegar on a plant in full sun will often result in a withered, brown plant in only a few hours, for sensitive weeds, or by the next day in tougher plants.
It is non-selective, meaning it might kill everything it touches. This limits the usefulness of a vinegar weed killer, to the extent that you are able to control overspray that would get on desirable plants.
Do you have places where you could use these characteristics of a vinegar weed killer? If it seems like a good idea, how do you use it? That brings up an interesting development
Source :
Vinegar Weed Killer: Grandma's Recipe For Fast Weed Control
Also see
Using Vinegar as a Herbicide
Regards
Harish