NEW HAVEN, Conn. — M. Edgar Rosenblum, longtime executive director at New Haven’s Long Wharf Theater — as well as an executive at a number of other theaters and organizations — died Saturday at his home in Woodstock, N.Y. He was 78.Rosenblum was part of one of the longest running executive-artistic partnerships in regional theater, serving with artistic head Arvin Brown from 1970-96. He arrived five years into the theater’s founding, steadied its financial footing and oversaw nearly three decades of work that included American and world premieres, New York transfers, co-productions and commercial affiliations and a Tony Award for the theater, After Long Wharf, Rosenblum worked for New York’s Circle-in-the-Square and Theater for a New Audience and the Berkshire Theater Festival in Stockbridge, Mass. Earlier in his career he was producer and manager if the Woodstock Playhouse in Woodstock. During his career Rosenblum was also president of the League of American Resident Theaters, the organization comprising the nation’s leading regional theaters, a chairman of the board of the American Arts Alliance, and was founding president of the National Corporate Theater Fund. Most recently, he was working for the California Intl. Theater Festival.