The Animation Guild’s TAG blog has confirmed that Disney will no longer produce new episodes of Phineas and Ferb. They quoted an anonymous Disney staffer who had worked on the series:

Most the Phineas and Ferb board artists are gone. It was a nice, five-year run but the series and the specials have wrapped and people are off to other jobs, looking for other jobs. A few artists are swinging to other Disney shows here, but others not…

UPDATE: On Twitter, Phineas and Ferb co-creator Jeff “Swampy” Marsh denies that the show is over in an aggressively worded series of tweets directed toward the Animation Guild’s business rep Steve Hulett, who reported the news. We have reached out to the Animation Guild for comment.

Contrary to Marsh’s claim, I have never known the Guild to be inaccurate on a cancellation notice. They represent the artists who work on the show, and if there’s anybody who would know if a show is finished, it’s the Animation Guild. There may, in fact, be new unaired Phineas and Ferb episodes/specials already in the can. What the Guild is reporting however—and which Marsh doesn’t deny—is that the new content has already been produced, and thus why the show’s crew was laid off.