Hi James,

Thank you for your question. The two plants that are pictured are In  Hairy Cat’s-ear (Hypochaeris radicata), a non-native perennial herb originally from Europe  is an annual flowering herb introduced from Europe and  White clover (Trifolium repens) is a legume introduced from Europe and has been used as forage for live stock since early settlers times. White Clover is a perennial with creeping stolons (runners).  It is not recommended to use vinegar or salt on weeds as this will also damage any plants or roots it comes into contact with. Salt and vinegar also can sterilize your soil, negatively impacting soil biome. Salt can kill roots preventing roots from absorbing nutrients. 

These plants may be removed mechanically, digging up the entire plant including roots. Note that Cat's ear has a tap root that should be dug out and White clover should be completely dug out including all  runners. Following removal put down black landscaping fabric and cover with 3 to 4  inches of mulch. Or add to the mulch that you already have in place making sure you are blocking the ground from light. Mulch should not go right up to your tree trunk.  The link provided discusses how a tree should be mulched.  Another approach would be to plant aggressive native ground cover under the tree, like Packera auria. 

Sawtooth oak (Quercus acutissima), although not listed as invasive in the state of Maryland,  is non-native introduced from Asia and out competes many native trees. Sawtooth oaks prefer well drained soil and thrive in loamy soil, the soil should have a  mix of sand, silt, and clay. Sawtooth oaks are able to thrive in varied climates.  Avoid sitting water, or soggy roots that can cause to root rot and decline in Sawtooth oaks.  It is hard to tell from the photo but the bark shows signs of overwatering or a pathogen infection. You should have the tree looked at by a reliable licensed arborist.  The tree may be stressed by both the pruning, the soil treatment, or perhaps over watering if the mulch is holding in too much moisture too close to the bark. You may want to have your soil tested, University of Delaware does soil testing and make sure it is the right make up for your tree. 

I hope this is helpful.

Best regards,

Christine