When was the "salad bowl" term introduced?

The phrase gained wider currency in 1908 during the great wave of slavic jewish and italian immigration when israel zangwills play ''the melting pot'' was produced.

It is false

Explanation:

Julius and Ethel Rosenberg were arrested in the Summer of 1950 and executed in 1953, they were convicted of conspiring to commit espionage by passing plans for the atomic bomb to the Soviet Union.  Harry S. Truman  was the president at that time.