i use the three to four foot tall green plant stakes from Lowes/Home Depot to mark all my plants that are not obvious to the weed sprayer/yard guys until the plants get growing and its obvious they are not weeds... (of course this didn't stop the idiot from TruGreen last year from spraying my lilac bushes and killing them)..
Anyway, quick talk with the landscapers and also ask them how they are going to make this situation right (i ended up getting my bushes replaced and a free year of services).. if you don't ask they probably wont offer any type of compensation... If i were you i would look up what a couple of pounds of hops (per each plant) costs and bring those numbers to the discussion as monetary loss incurred due to their actions. They can write it off and you get at least compensated for any possible damages they may have caused to your harvest.
Here's another idea for protecting the hops and obviously marking them until you get the trellis(s) up cheap at lowes for like $6 each (they are for tomatoes etc and fold up when not needed anymore... and i use them basically to protect my hops from my dogs and the GF's idiot kid who like to wander through my flower/hops beds).