Industry evolution
Beyond the Hass: The Diversity Studyed at UC Riverside
UC Riverside gathers nearly 1,000 avocado varieties to develop alternatives to Hass
October 6, 2026
The avocado has a diversity that far exceeds the best-known varieties on the market. The University of California, Riverside (UCR), in the United States, offers a database with nearly 1,000 variety names and maintains breeding programs spanning more than seven decades, with a collection of genetic material for scion varieties and rootstocks.
Both resources serve different functions: the database allows users to consult varietal information, while the breeding material is part of the work aimed at developing new selections. Therefore, the number of registered names does not equate to an inventory of varieties created by the university.
Why is the industry looking for alternatives to Hass avocados?
In an analysis published on the UCR website , horticulturist Mary Lu Arpaia explains that the Hass avocado combines good eating quality and favorable post-harvest attributes, but also has limitations. Alternating bearing, sensitivity to extreme weather conditions, and fruit size issues, especially as the trees age, are factors that the university considers in its research.
From this perspective, breeding seeks varieties capable of more consistent production. Arpaia also suggests that an industry with greater varietal diversity could help limit the spread of certain pests and diseases. These are research objectives that require evaluating the performance of each variety.
The program addresses two components of the tree: the fruit-bearing varieties and the rootstocks, onto which these varieties are grafted and which provide the root system. This distinction helps us understand that avocado breeding encompasses both the characteristics of the fruit and the material that supports its cultivation. UCR brings together genetic resources for both lines of research.
Luna UCR: The variety that represents decades of genetic improvement
A concrete example is Luna UCR, introduced by the university in 2023. According to the institution, it combines high-quality eating and post-harvest characteristics with smaller trees, allowing for denser plantings and easier harvesting. Its skin darkens as it matures, and its floral characteristics allow it to be used as a pollinator for other varieties, including Hass.
Its development dates back to work begun in the 1950s and continued by different generations of researchers. This trajectory shows that obtaining a new variety is a long-term process, in which previous selections can provide the foundation for subsequent advances.
Luna UCR's history has its roots in Gwen, a variety developed by researcher Bob Bergh and introduced in 1983. According to the university, Gwen combined good flavor, annual production, and smaller trees, but had little commercial success because it retained its green skin when the market had already adopted the dark-skinned Hass.
Bergh continued working with seeds from Gwen trees, and among their descendants emerged the tree that would give rise to Luna UCR. His story shows that a selection with agronomic advantages can contribute to improvement, even when it doesn't achieve commercial success.
The interest in this diversity lies in the possibilities it opens up for the industry: evaluating materials that respond to production challenges and, at the same time, maintain the characteristics demanded by the market.
