You can try this for weeds. Weed-be-gone works in 24-48 hours and round-up works in 7-10 days so I 've been mixing them 50-50 for years and it takes care of even the poison ivy/oak vines going up trees (without killing the tree). There was a commercial weed killer years ago that you were to mix with fuel
oil or diesel fuel with, I can’t remember the name (really worked well) today it's EPA registered so you need a license to buy now.
Another thing you can do for poison ivy. Do not mulch around plants were poison ivy lives (poison ivy seems to grow WELL in mulch) try using shredded /chipped wood. You can get it free from tree services when they are working in your neighborhood (they usually have to pay to dump there chips!) They will usually give you (gladly) the truck load. This chipped wood and branches is acidic as it breaks down and poison ivy does not like it. And it will last for 2-3 years, I use this in my wooded area and it works well.
Take care, Jon