UPDATE: I tracked down a copy of ANSI MH6.1-1968, "Pictorial Markings for Handling of Goods" at the Linda Hall Library in Kansas City and (once we got copyright permission from ANSI) they scanned it for me. It's a cool old document but it did not contain the PERISHABLE symbol.
With ANSI MH6.1 out of the running, there is one remaining likely candidate in the bibliography from Henry Dreyfuss's 1972 "Symbols Sourcebook" and that is a system of signs Herbert Lindinger made or compiled for Olivetti
I emailed the Olivetti Archives a couple weeks ago and have not heard back. I have been looking for information on Herbert Lindinger and it looks like he may still be alive! Or if he died, nobody has updated his wikipedia page.
I have not found a contact for him yet but have emailed a German university he was associated with to see if they have any way to contact him.
What if this is the designer of the label and he is still alive??