The Islip Arts Council says it was notified in a letter signed by Philharmonic President Zarin Mehta. It said the Philharmonic has been affected by "the financial realities of the day."
The council has instead asked the Long Island Philharmonic to perform at Heckscher State Park on July 18.
Neither the council nor the ensemble of freelance Long Island musicians knows yet where their funding will come from.
The annual concert-in-the-park has been held since 1977. Last summer's concert, including a Grucci fireworks display, drew nearly 67,000 people.