I will retract my recommendation above. Unless the sickle is designed for heavier brush, the blades take a beating on anything more than grass/hay. Hit a thicker hunk of wood? Hit a small stone? Hit wire? You will spend the next few hours with some special tools and spare blades to sort it out.
I recently hit a small piece of wire fence that a deer must have dragged into the field. It tangled into the bar. 6 blades later, two guides, and a LOT of cursing plus two trips to the store I had it working again. It only took about 6 hours to fix.
They are meant for very light cutting only.
