Attracting an African-American audience to productions of August Wilson plays can be surprisingly tough. Or so goes the conventional wisdom on Broadway.But the current revival of “Fences” bucks that notion. Since the Denzel Washington topliner began previews on April 14, the show has regularly pulled in crowds that strike an equal balance between black and white, according to those associated with the production. “What I find exciting is, our audiences look more like America,” says helmer Kenny Leon, who also has directed Wilson’s “Gem of the Ocean” and “Radio Golf” on the Rialto. The wide appeal can be attributed to the production’s canny combo of casting — with an ensemble led by Washington and Viola Davis — and title. “Fences,” which centers on the marriage of a charismatic sanitation worker and his wife, is considered one of Wilson’s most naturalistic and accessible works. Although the traditional Broadway demo is still generally thought to be made up of older, primarily white, theatergoers, past Main Stem successes — including “A Raisin in the Sun” (also directed by Leon) and “The Color Purple” — have proved African-Americans will certainly turn out for the right offering. Wilson plays, however, aren’t often on that list. “The two stars have, I think, bridged that,” says Scott Rudin, who produces with Carole Shorenstein Hays. “The stars expand the reach of the play.” Washington, of course, proved his B.O. power with the 2005 revival of “Julius Caesar.” “Fences” has played to robust grosses since it began perfs, and now with strong reviews under its belt, the show looks certain to power through the remainder of its limited 11-week engagement. Will there be a Tony for original score this year? That’s what some legiters wonder, given that there are only two tuners, “Memphis” and “The Addams Family,” with scores eligible for the category in a season dominated by catalog- and album-based musicals including “American Idiot,” “Come Fly Away,” “Million Dollar Quartet” and “Fela!” There are a few possible outcomes when the Tony noms list is announced May 4. The Tony nominating committee always has the option of scratching a category entirely if members feel there aren’t candidates of sufficient quality or quantity to vie for a trophy. It happened in 1989, when the categories for both book and score were eliminated. That was the year “Jerome Robbins’ Broadway” won the top musical prize, and another revue of pre-existing songs, “Black and Blue,” also was on the list of tuner nominees. The third nominee was sci-fi tale “Starmites,” one of the Main Stem’s more memorable failures, and no fourth show could be drummed up to make up the category’s traditional quartet. This season, the nominating committee could instead decide to tap only one of the eligible shows. When that happens, the single nominee wins by default, as in 1995 when “Sunset Boulevard” took home the award for score after a hard-fought struggle against, uh … nobody. (“Sunset” also won the top tuner prize in a fallow season that only yielded one other nominee, the revue “Smokey Joe’s Cafe.”) Or, of course, nominators could decide to put up both eligible musicals. In which case, the race is on — but with a couple fewer horses on the track than usual.