Round up is fine for the back yard and we do use it but 8 acres is pretty tough. I spent the last two weekends detangling bind weed, brambles (aka wild rose) and poison ivy which had grown up with a few trash trees under the biggest tree on our property. I scrub down with poison ivy soap and creams and shower and wash my clothes but still get it. I think I need a gas mask and a flame thrower. This area had been sprayed with round up over the past three years.
A flame thrower sounds good. Make sure you’re upwind.
If I had eight acres and a herbicide sprayer I would write a satiric message in the grass that could be seen from space :0)
Round up is not effective on poison ivy. Go down to your county extension office, they will assist you with the proper sprays.
I use an axe to cut poison ivy vines out of trees. I found vines 3 inches in diameter. I use a mower on the rest. If you can mow it, it will eventually disappear.
spraying with Roundup—
Instead read the label for products that are for woody brush-different product. I use it on trash trees, spraying the leaves, waiting a couple of weeks til dead- it takes out roots and all. Then I clip it near the ground and that is that. This kind of product is labeled for poison ivy.
I also sometimes cut a small trash tree, immediately (before the small trunk can seal over) brush it with full strength brush killer- wear heavy rubber gloves when you do this-that will kill down to the root also.