By Lenn Thompson, Editor-in-Chief The Hudson River Region has a clear-cut signature white grape variety — Seyval Blanc. On the red side of things, the most planted grape seems to be De Chaunac, but I don't know any winemakers who are excited about it. It's so widely planted because it's easy to grow. Period. Baco noir is only being bottled varietally by a handful of wineries in the region, but it seems to show the most potential among the hybrids that thrive along the Hudson River, and Benmarl Winery in Marlboro, NY has been growing it and making wine from…