This comment is misleading. Every type of produce had a preferred shipping temperature and the range was very broad, from 33 degrees to 65 degrees or more (Fahrenheit). In the fall, cooler weather meant that crops like potatoes and onions, at the upper end of those temperature ranges, could be shipped with ventilation only and achieve the desired temperatures. But that depended on outside temperature, so a blanket statement that a kind of produce "didn't need icing" cannot be general.

      The USDA table of those temperatures is on page 345 of the PFE book.