Deer will eat tender new grape leaves and branch shoots first, but they will also eat older leaves and even chew on woody grape vines. Deer may also leave scratches in the thick bark of the main grape vine.
Creating a barrier that prevents the deer from reaching the grape leaves is a humane way to protect your vines, but it's not always effective. Deer can leap over fences, and "deer tubes," which encase the lower vine, do not reach high enough to protect the leaves. Deer netting spread over the tops of the grape vines is beneficial if the grapes are grown vineyard-style, in limited-height rows. If the grape vines are free form, winding their way up tree trunks and through thickets, deer repellent is a better choice.
Chemical deer repellents, available in gardening centers, must comply with state regulations. The repellents work by putting off a disagreeable order or taste that discourages the deer from grazing on the leaves. These repellents are safe when applied according to the label directions, but overuse may lead to plant damage.
Natural alternatives to chemical repellents contain ingredients deer frequently associate with their enemies or predators. Spreading human hair near the grape vines may repel deer who do not like the strong smell of humans. Bloodmeal and feathermeal may repel some deer. Additional repellents include mothballs and creosote. The University of West Virginia report suggests using a combination of repellents for the best results.