University of California researchers build a better avocado tree

The Luna UCR avocado is similar to the Hass, but may benefit growers

A new avocado variety developed by UC Riverside researchers could be available in grocery stores in the coming years.

The Luna UCR avocado will soon be available to growers worldwide, though it will take a little longer before it is available in supermarkets.

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The Luna avocado, the result of decades of research, tastes similar to the popular Hass avocado, which dominates the US market. However, significant differences, such as its compact tree shape and flower type that can pollinate other avocado trees, may distinguish it for growers and others in the industry.

According to its website, UCR’s avocado-breeding program, which has been in operation for about 70 years, partnered in 2020 with Eurosemillas, a Spain-based agricultural commercialization group that has worked with the University of California since 1989.

According to a July UCR news release, Eurosemillas has partnered with growers in 14 other countries to cultivate the Luna.

It’s not uncommon for UCR or other public institutions to develop new plant varieties for the industry or general public, according to Eric Focht, a UC Riverside staff research associate in the Botany and Plant Sciences Department, in an email on Wednesday, Aug. 16.

Other plants developed by UCR include avocados, citrus, and asparagus.

However, he claims that there has been a decline in publicly funded breeding efforts in recent decades, possibly due to the high short-term cost.

It takes about two decades to release a new plant variety that was grown from seed, and “that’s not a quick turnaround,” according to Focht.

The Luna avocado took a long time to develop.

Berthold “Bob” Orphie Bergh, described as UCR’s “first real long-term avocado breeder” in a UCR news release by Mary Lu Arpaia, began avocado research in the 1950s.

Arpaia, along with Focht, Bergh, and others, is a UC Cooperative Extension professor of subtropical horticulture and one of the researchers on the Luna UCR patent.

“A really important point is that when you have a breeding program, especially for tree crops, you build upon the success of your predecessors,” Arpaia explained on Wednesday, Aug. 9.

Bergh initially sought an alternative to the country’s most popular avocado at the time, the Fuerte, which Arpaia claimed had production issues such as erratic fruit-bearing and a sprawling tree shape. According to the UCR release, there was already an alternative, the Hass, but it was unpopular with consumers because the skin turns black when it’s ripe.

By 1983, Bergh had developed the Gwen avocado, which remains green — but by then, consumers had grown accustomed to the Hass avocado, thanks to marketing and technology that enabled more uniform ripening.

Bergh planted up to 70,000 avocado seeds from Gwen mother trees in the mid-1980s in search of future varieties, according to UCR.

That batch of seeds produced several new varieties. Luna will be the last of them to be released, according to Arpaia.

The Hass avocado was named after its inventor, Rudolph Hass, while the Gwen avocado was named after Bergh’s wife. Arpaia’s dog inspired the name Luna.

“We were having trouble coming up with a name,” she admitted.

While brushing Luna one day, “a lightbulb went off.”

The Luna avocado will appear similar to the Hass variety to consumers.

According to Focht, Hass avocados currently account for 95% of the global avocado market.

While their shapes differ slightly, Hass and Luna avocados have green skins that turn black when ripe, and Focht describes the Luna’s flavor as “very Hass-like.”

Apple varieties are a good analogy for how different avocados taste, according to Arpaia.

“You go to the store and see all these different varieties of apples, and they all taste like apples, but they’re subtly different,” she explained.

She claims that the difference between avocado varieties is more subtle, though they “vary quite a bit in texture.”

She described the Hass as creamy, the Luna UCR as smooth, and the Gem as meatier.

Researchers are interested in the avocado fruit. Another example is the tree.

Focht pointed out the different shapes that make trees more or less desirable to growers in a sunny avocado field near UCR.

“Traditionally, we’ve looked at something like a narrow cylinder or column as the ideal tree shape,” Focht explained.

More upright, compact trees, such as the Luna, take up less space, allowing for more planting in a given field.

Carl Stucky, a board member of the California Avocado Society and an agricultural consultant, stated on Tuesday, Aug. 29, that the tree’s shape benefits “higher-density planting.”

Other considerations exist as the industry explores new directions, such as the use of trellises, according to Focht. While researchers do not yet know how the Luna would react in that situation, Focht stated that “we suspect it should do well,” and trials are in the works.

“There are many different situations that a field can present, and it’s likely that no single variety will fit all of those,” Focht said, but the Luna is “the perfect fit for what we’ve been focusing on for 50 to 60 years.”

The Luna’s flowers are another potential advantage.

According to Focht, avocado trees have one of two flower types and will cross-pollinate with trees that have the opposite flower type.

According to Focht, the fruit of the avocado tree variants being planted today to cross-pollinate Hass avocado trees has little market value. That means that the 10% to 11% of a field taken up by those variants often goes to waste, because picking the fruit may cost more than a grower would make selling it.

Arpaia believes it will take a few years for Luna avocados to be widely available, and that they will likely first appear at farmer’s markets, then at higher-end grocery stores like Whole Foods, and then at other chains like Ralphs.

In the meantime, the trees will be distributed to growers. Arpaia stated that they will first be used as pollinators before being planted in greater numbers.

The Luna isn’t expected to generate revenue for UCR for several years, according to Brian Suh, UCR’s director of technology commercialization, in an email on Wednesday, Aug. 16.

According to Suh, royalties will be distributed in accordance with UC’s patent policy, which allocates 35% to inventors, 15% to research, and 50% to the campus for multiple uses.

Stucky, on the other hand, sees “real problems” with how the Luna is being marketed, specifically the fact that there will be an upfront fee and an annual royalty for the life of the trees, which is “definitely unusual for avocados.” According to him, new varieties typically have a low, one-time patent fee.

Stucky also mentioned that the California Avocado Commission contributed to the program’s funding.

Suh stated in an email sent on Friday, Sept. 1, that as a result of his contribution, California growers will receive royalty fee reductions. In addition, he stated that UCR is collaborating with Eurosemillas to develop a short-term, royalty-free option for California growers’ first five acres.

DUE TO THE NUMBERS

From 2015 to 2017, California accounted for 86% of all avocado production in the United States.

40% — The percentage of avocados imported into the United States in the early 2000s.

90% — The percentage of avocados imported into the United States in 2022.

SOURCE: United States Department of Agriculture