I live in VA, in the Appalachain Mountains, with plenty of wild turkeys. I do not have experience in something that will keep them away. I do know that anything that works with wild geese (have some of them, too) will work for turkeys.
Here is a link: 5 non-harmful ways to control Canada geese on lawns, golf courses, and atheletic fields
These windmills listed in the link above might just do the trick. I do know that keeping birds out of fruit trees is an art. I use to hang aluminum strips in Peach trees, keeping out Mocking Birds and others, who love fruit. It works.
Motion with flashing sunlight reflections will scare away birds.
If you do some research on the web, there are also Turkey repellents that are sold. Although I've never used them, they might work. Best of luck.
A friend down the road has a high fence (about 6 feet) around her corn, and it does help some, but doesn't keep them all out.