"DON'T MESS with my fest!"

For sure, some old-school folkniks attending this weekend's Philadelphia Folk Festival will be whining that line.

But we're thinking that the general populace will rejoice at some offbeat bookings for the 52nd annual get-together on the Old Pool Farm, in Upper Salford Township, acts intended to make this homey event even more user-friendly and connectable.

As ever, there's lots at the fest that qualifies as tried and true folk music, from Celtic talents (Burning Bridget Cleary, RUNA) to earthy blues (Carolina Chocolate Drops, Otis Taylor), with bluegrass (the much buzzed about Decemberists' spin-off, Black Prairie) and Americana twang (the Mavericks), plus cool world beat-ers (Sierra Leone's All-Stars, Hawaiian uke master Jake Shimabukuro) and earnest singer-songwriters like Boston fave Ellis Paul.

But for the first time ever, this year's PFF also will celebrate Philly rock and roll in abundance. An especially big blast ignites tomorrow night, when the main-stage bill includes veteran Philly rockabilly Ben Vaughn with his quintet, the uber-versatile Upper Darby export Todd Rundgren and the rotating troupe of veteran local singers/players who answer to the name David Uosikkinen's In the Pocket and make it their mission to dredge up and pump out classic Philly rock-'n'-soul oldies.

Also sprinkled through the weekend are Philly fantastics like Jeffrey Gaines (making his long-overdue fest debut), genre melding Toy Soldiers and area-rooted artists like South Jersey/Texas swing legends Asleep at the Wheel and one-man-fest David Bromberg.

"Philadelphia is the first name in this festival, so it's important to dig into Philly roots music of all kinds," said Jesse Lundy, one of the two talent bookers (along with Rich Kardon) who argued (successfully) for inclusion of this local rockin' contingent. "And let's get real. Most of the people who attend this festival are really rockers. Whenever a musician throws in a quote from, say, a Grateful Dead tune, the crowd goes crazy."

Truth is, a festival that doesn't pay some attention to what its audience loves is a festival that will soon be out of business. "Half the acts that now play at the Newport Folk Festival aren't folk, half the acts at Monterey Jazz Festival aren't jazz," noted Rundgren, a musical wizard (and true star) who's worn many a musical hat in his career, from blues to Broadway, haunting pop ballads to spaced-out prog rock, cocktail jazz to his latest, electronica-flavored "State" of album being.

"Today's younger audience doesn't draw the same lines, the same distinctions between styles that people used to do," added the mercurial musician/producer. "If you want to reach them, broaden your base, you have to loosen up."

Some guys in the folk community have always preached the theme of "inclusiveness." The great bluesman Leadbelly (author of "Goodnight, Irene") famously declared that "I ain't ever heard no cow sing, it's all folk music to me." And the ethnomusicologist Alan Lomax (who discovered and recorded Leadbelly in prison) first got himself in hot water with the folk police way back in 1959, producing a Carnegie Hall concert that dared to mix the likes of Arkansas country singer Jimmy Driftwood, blues greats Muddy Waters and Memphis Slim and the R&B harmony group the Cadillacs.

Givin' a Hoot

When not sitting behind the drum seat for the Hooters, David Uosikkinen has unofficially taken on the job of curator for Philadelphia pop and rock history, though he laughs at a suggestion that he's the modern, local answer to field collectors like Lomax or Francis James Childs, the folklorist whose cataloging of old English and Scottish ballads would inspire everyone from Joan Baez to the Dead and Decemberists.

Every three months or so, Uosikkinen gathers a bunch of veteran Philly talents in a recording studio and cuts a new version of a classic rock or soul song spawned in these parts, mostly from the flush-with-success 1960s and '70s, when his own musical consciousness was awakening.

He releases the recording as a 99-cent MP3 download at songsinthepocket.org (Settlement Music School shares in the profits) and gathers the clan for a celebratory concert at a local club or theater. There will be 17 people on hand for the Folk Fest appearance!

"Philly was such a hotbed of activity, and even then there was a lot of commingling of styles that made our scene unique," he said. "The Hooters were certainly influenced by the reggae and folk-rock bands that WMMR played back then, like Bob Marley & The Wailers and Fairport Convention." The latter's brilliant former guitarist, Richard Thompson, will face the PFF crowd tonight with his own, very rocking Electric Trio.

For his part, Rundgren will stick mostly to his hits, "doing what I call my Arts Center set, the songs I do for the audience that might not know me all that well." That would imply the likes of "Hello, It's Me," "Can We Still Be Friends?," "We Gotta Get You a Woman," "Bang the Drum All Day" and "It Wouldn't Have Made Any Difference."

But given this is the Philly Folk Fest - which Rundgren visited "once in my Woody's Truck Stop days as a spectator, mostly to catch Jesse Colin Young" - we're thinking it'd be cool if he also revisits his folkie anthem "Love of the Common Man," or blues roots with a wailer like "Black Maria." Or maybe haul out one from "Todd Rundgren's Johnson," his 2011 album tribute to the songs of Robert Johnson. Yeah, Toddy's covered all the bases.

As for the future of the PFF, Lundy suggests that "we're not going to go overboard, even if this experimental Philly rock-heavy night goes over well. The fact that we still take folk music seriously sets us apart from almost every other festival out there. And it's still our middle name."

Online: ph.ly/Tech