Marestail, Equisetum arvense. It is an absolute devil to get rid of. Roundup will work, but you need to bruise the foliage first and add a little washing up liquid to the mix to make it stick to the leaves. Even so it takes a long time and a lot of work.
Sorry.

You will find two kinds of shoot. One as in your picture and the other with a sort of club shape on the top. Best cut the latter off as soon as you see them as they are the spore bearers.

Horsetail is the correct term as marestail is actually an unrelated aquatic. There is no substitute for vigilance and constant hand weeding (daily if possible) to deprive it of growth potential. Eventually it will give up on you and move on via its 2 metre deep rhizomes.
Weed-killer can be a problem as all the other plants are killed giving it a free run. It is fairly resistant thanks to a wax coat so needs a special preparation with a strong detergent and pre-bruising as stated above, but still you would be lucky to kill the deepest roots.