wiki

Then there's the nuclear option–chemical warfare. For me this a last resort.

Glyphosate is a non-selective systemic herbicide that is applied directly to plant foliage. It is a non-selective herbicide, meaning it will kill most plants. It prevents the plants from making certain proteins that are needed for plant growth. It is only effective on actively growing plants and cannot prevent seeds from germinating. After application, glyphosate is readily transported around the plant to growing roots and leaves and this systemic activity is important for its effectiveness. It causes an enzyme to accumulate in plant tissues that diverts energy and resources away from other processes, eventually killing the plant.

For details see Wikipedia: https://en.wikipedia.org/wiki/Glyphosate.

I have used it a couple of times in isolated areas for spot treatments, either with a small brush or with a low-pressure sprayer.

My first experience with mass infestations of invasive plants was sheep sorrel. I have used it a couple of times to kill sheep sorrel (in isolated areas), which has nasty rhizomes that will expand for yards beneath the ground in one season. Before your vegetable plants start producing you'll have a big patch of these plants spread out over a large area. OK, so they are edible - I hope you love them if you let them propagate. They can take over a garden.

As I conjecture a package of vetch cover crop contained the minute seeds of this rapidly proliferating perennial weed, which is difficult to eradicate due to its persistent seeds and ability to reproduce vegetatively through rhizomes. I saw that suddenly there was an area of about 100 square feet with strange sprouts along one section of my garden.

I tried painting them with a glyphosate solution on the leaves and waited. The existing leaves withered, but the rhizomes in the ground continued to generate new ones and the infestation wasn't contained.

In a case like this, the only recourse is to dig up all the underground rhizomes along with the sprouts and destroy them. Composting them is obviously not going to be effective. This was my first, and not last experience with the persistence of rhizomes and the limits of glyphosate.

See also Loathesome weeds.

My next experience with the limits of glyphosate was on the property here at Sun Mountain Farm. Two grasses, reed canary grass and creeping sedge rush, infesting the majority of the land of our property, proved to resist the destructive power of glyphosate. While stems above ground withered and turned brown, new sprouts quickly replaced them. Again, the only effective way to remove these grasses is to dig up them entirely.