I personally don't use herbicides as I prefer to taproot-remove weeds and prevent weeds. I try to prevent infestations of weed infiltrating rock beds and side drives by diligently removing the taproot at the early stage, when its shoot begins to emerge and well before spreading and flowering.
Here are alternatives to killing most weeds or stunting stubborn weeds (bindweed) or invasive elms:
Tarp weeds in rock—Apply a tarp or contractor glad bags over the rocks, and small boulders to secure the tarp. Do so for the entire summer to burn via increased temps and to deny sunlight (photosynthesis). Circle back and remove the taproot of survivors.
Cardboard-mulch weeds in soil—Cover ground with cardboard (like the free, large ones our bike store recycles), weighed down by small boulders or mulch. Circle back and remove the taproot of survivors.
Release bindweed-eating insect—Consider getting the bindweed eating gall mite (Aceria malherbae) from the Palisade Insectory. I used to think that this insect was "engineered", but it made its own evolutionary place on our planet and conservation groups make use of this insect. This apporach is useful if you don't want to eradicate the weed via herbicides or taproot removal: the insect is known to reduce bindweed by 25%. Insect will not survive where there's no bindweed—and they won't travel beyond your yard.
Remove invasive elm trees with Hi-Lift Farm Jack—As a tip, I've removed 5-year old trees on my own property without specilized equipment by removing all branches with a sawsall, cutting trunk down to 4' height, soaking trunk with water day before, then straping trunk to truck hitch and giving it some gas 4-5 times before trunk comes out, rootball and all. (I can't promise that saplings won't return.) Obviously this only works if the location of the tree is accessible my truck; in that case, use a Hi-Lift Farm Jack.
However, I see the appeal of poison if:
You have an entire "field" of bindweed in your aggregate and your budget doesn't support landscape maintenance services
The weed's taproot are under concrete cracks and nowhere near plants or sidewalk/storm drain
Your sprinkler lines are at shallow depths
You're using Tordon RTU mature elm trees; however, if there's an herbicide that kills an elm, then that's a strong chemical, and yet I still can't promise it will work.
But, know that you need one or more applications to kill bind weed, and there will still be survivors even when you use Roundup. Moreover, there are risks to contaminated storm water (river water). As such, use as a last resort. Consider design changes instead.