Redblush originated as a bud from a Thompson Seedless.  The mother tree had been budded to a Thompson or Pink Marsh in May of 1929 but had frozen back within 2 inches of the bud union in January 1930.  Later a sprout was put out by the stump of the bud.  In September 1931 it bore fruit somewhat larger than that of the Thompson, the color showing as flush on the rind.  When cut the fruit was found to  be mush deeper red than the Thompson.