It's avocado season. Specifically, it's the part of avocado season when Riverside's Farmers Markets start transitioning from the green thin-skinned varieties – Bacon, Fuerte and Zutano – to the black thick-skinned Hass variety. Hass is the world favorite. An estimated quarter billion (with a "b") pounds of avocados (the great majority being Hass) were consumed for 2025's Super Bowl Sunday alone. Mexico is the world's primary producer of avocados (mostly Hass), and California is the number one avocado-producing state (95% Hass). And the Hass truly has its roots in Southern California.
It wasn't always this way. In the early days of the avocado in California, everybody "knew" that a black-skinned avocado was a rotten avocado. Fuerte – so named because it survived the terrible frost of 1913 – reigned as avocado royalty for much of the 20th century.
Despite its cold tolerance, productivity, tough skin (relative to its peers) and nutty flavor, Fuerte has its flaws. Its short season annoyed the consumer. And its strong tendency for alternate bearing annoyed farmers. Alternate bearing starts when a tree is stressed. It will drop all its fruit during a cold snap or heat wave, only to have a boom year the following year, followed by a bust year, and so on. If a temperate stress hits a whole region, the entire region starts alternate bearing. Everyone has abundant fruit during the boom ("on") years. The extraordinary supply sends prices plummeting. During the alternating barren ("off") years, demand remains at the same level, prices are high, but production is meager. Fuerte is particularly sensitive; even the "stress" an unusually good bearing year can induce alternate bearing in this variety. Another shortcoming was the fact that Fuerte was picky about its tolerance to certain Southern California microclimates.
Resourceful amateur and professional horticulturalists were experimenting with alternatives to Fuerte. One such experimenter was Whittier postman Rudolph Hass. In 1926, he bought three seedling trees to use as rootstocks for Fuerte. Hass repeatedly tried grafting, but one of the three seedlings rejected all of his attempts. Hass didn't remove the wayward tree, but he neglected it. In fact, Hass was repulsed by the seedling's fruits.
Fuerte's fruits are sleek, green and smooth. The Ugly Duckling's fruits were grenade-shaped, dusted with black, very thick-skinned and pebbly. When its mature fruits were allowed to ripen, they turned purple-black.
Nonetheless, Hass' kids tried the fruits themselves (perhaps inspired by neighborhood dogs gobbling the fruit). They begged him to give the fruits a chance. "You gotta try it, Dad!" Rudolph conceded, and there was no looking back. Not only did the flavor change his mind, but he had already noted that the trees held fruit for an extraordinarily long season. Fully converted, Hass promptly named the tree after himself and received a U.S. Plant Patent in 1935.