Visual deterrents such as shiny tapes and streamers can be hung near the grapevines. Though cost-effective and easy to install, this method is not typically enough on its own. A physical barrier such as netting is more effective at keeping birds away though it can be difficult to install. The most common and least expensive netting is the lightweight, black, polypropylene type with a square mesh size of ½" x ½". Woven mesh bird netting is also effective and easier to work with but is more expensive. If your trellis has a wire at six feet high, purchase a net that is at least 14 feet wide so that it can be draped over the grapes and secured along the bottom edge with clothes pins. Nets that are 17 feet wide are less common but give more material to work with and are therefore easier to secure.
Another option for a physical barrier is to secure paper bags around the grape clusters. The bags can be kept in place until harvest. (Cynthia Domenghini)