According to this website,
http://www.topcropmanager.com/content/view/3850/38/ barley, wheat, and oats all self-polinate, and therefore different types of these plants can be grown in relative proximity without risk of cross-polination. Rye, apparently, is different. If this information is accurate, and I have every reason to suspect it is, then you need not worry about mischeif from your neighbor's barley.
Hope this was helpful, if not altogether timely.
