LOS ANGELES — Most summer school programs for students from elementary through high school will be canceled this year, the latest casualty of California’s widening budget gap, the superintendent of the Los Angeles Unified School District said Friday.

Core curriculum courses, available only to those who need credits to graduate, will remain open, the superintendent, Raymond C. Cortines, said. But other summer classes will not be offered, nor will non-academic programs like recreational activities for younger children, Mr. Cortines said, leaving many whose parents work at loose ends.

Students who do not need credits will be shut out of courses like math and English.

Roughly 225,000 students attend summer school in an average year, a district spokeswoman, Gayle Pollard-Terry, said.

“This is unfortunate,” Mr. Cortines said of the cancellations. “This goes against my education values, but I have cut in every area, and the cuts I made first were farthest away from students.”

The decision also affects thousands of teachers. Many count on income from summer teaching jobs, said A. J. Duffy, president of the local teachers’ union, and come fall, teachers will have the added burden of helping students who did not get the academic instruction they needed over the summer to catch up.

The district has already cut $563 million from its budget, and will save an additional $34 million by the summer program cancellations, Mr. Cortines said.