You might want to look again... the grass has nothing to do with it. It's the selected, orange object that is in question in my example.
For ropes, I generally just use thin cylinders. For game stuff, I'll usually make them 3-sided cylinders.
But for tears and rips and so on, I generally use transparancy maps, unless the project calls for something different.
As for the rope's texture, you can make it in Photoshop using photos source, hand painting, and/or both.