well... my dogs are very obetiant but we let them out at night to guard the property, thats when they wander off. Also when my dogs were comming when i was calling for them the other day, they were comming from across the road when i was calling their names and they almost got hit!
Well I would imagine that they aren't doing a very good job of guarding any crops if they are continually running away. So to avoid them getting hit by a car, or shot by a neighbor, I would leave them in the house until your fence is built.
I have heard of Akbash guarding a variety of things, but crops is a new one. A large part of training them to guard something is in the bonding process and mostly what they guard are flocks of animals. They must bond with what they are guarding if they are going to be an effective guardian. Maybe if you worked on bonding them to the corn stalks and tomato plants they'd get the idea. And I cannot believe I even just typed that because it sounds totally ludicrous.
Maybe you should try joining this email list that is comprised of owners of your breed and other breeds just like them for better information on how to train your Akbash. The majority of owners on the list use their dogs for what they were bred to do and might be able to help you figure something out.
Even dog that are used to guard flocks, etc have confines of a fence around them. If you know they run off, then they should not be turned out to guard at night until the fence is complete!
Absolutely anything can happen to them at night when they are off wandering. Keep them in the house at night until the fence is complete and secure. Druing the day, a leash or a tie out (tie outs are only safe if you are home to supervise)
Life isn't about waiting for the storm to pass. It is about learning to dance in the rain.