Greenbrier (Smilax) is widespread in Maryland and all 10 or so species documented here are native. (Officially, noxious weeds that are regulated are non-native species.) Birds consume their berries and spread seeds around, so their return to the same habitat is likely in the future. In that case, though, seedlings will be by their nature small and easy to remove in their entirety.

In lieu of herbicides, the only control measure is physical removal. While tedious, it eventually starves the root system by continual removal of all of the plant's top growth. Some Greenbrier species are notorious for rebounding easily after attempts at removal, even after fires, due to viable root fragments left behind in the soil. You don't have to remove roots if all the foliage can be consistently and vigilantly removed, but digging roots out will at least reduce how much regrowth the plant can produce.

To make removal a bit easier, you could consider hiring a herd of goats to browse the vines, though this may be more expensive than using herbicide would be. Plus, its viability will depend on site conditions and how many desirable plants are mixed-in with the Greenbier and whether or not the goats will also want to consume those. Browsing won't kill the plants, but will weaken them to make other control efforts easier.

If you do need herbicide to gain the upper hand, cut back what Greenbrier growth you can and treat the re-emerging foliage by painting-on the chemical with a disposable inexpensive foam brush. This way, the amount of herbicide needed will be much reduced, the application can be very localized, and no other organisms should be exposed. Follow label instructions about dilution if the product isn't already formulated to be ready-to-use. A systemic herbicide will be absorbed by the Greenbrier leaves and moved into the roots, which will make control more successful.

Miri

Understood...and yes, they are more practical when enough land is available.

Miri