Aug 18, 2020
Efforts under way to improve the world’s ‘best’ peach

Colorado-grown Palisade peaches are ranked first in the country when it comes to value of the product per-pound, making them the most expensive peaches in the world.

Challenges in evolving the peach crop

Colorado State University College of Agricultural Sciences’ Ioannis Minas, a pomologist and assistant professor within the Department of Horticulture and Landscape Architecture, is at the forefront of Colorado peach development. Since arriving at CSU in 2015, he has worked to make the crops more resilient, efficient, productive and, of course, tastier. But given the unique environment peach growers work with in the Rocky Mountain region, that mission comes with its challenges.

“Land that is suitable for fruit production is very limited and demand for Colorado peaches across the country is very high, so in order to expand the industry, there’s no way to expand into new land,” said Minas, who is the leading peach rootstock researcher in the country. “We are trying to find rootstocks that can fit into modern stone fruit production for high-density plantings to create efficiency in production, to lower cost of labor, and produce more in the same area of production.”

Aside from limited land, Colorado peach growers are also faced with Cytospora canker, an opportunistic pathogen that accounts for 20% of annual crop production loss, and the potential for extreme freezing events, which hit this industry earlier this Spring and will have a detrimental impact on this season’s crop. Suffice to say, Minas deals with multiple tiers of challenges in his research. Much of his research distills down into three factors: Rootstock, cold hardiness and how orchard factors impact quality.

“Rootstock is the most important aspect of modern fruit production,” said Minas. “It underlines many aspects of production. And once planted, you can’t remove it without having to rip out the entire crop, so the selection of root stock is very critical.”

In 2017, Minas was elected to serve as the project coordinator for the North Central Regional Multistate Project (NC140) regional rootstock research trials for peaches across North America. The NC140 scientific coordination team is a de facto international leader for temperate zone tree fruit rootstock science. Minas’ Pomology program includes close outreach collaboration with the tree fruit industry to coordinate the applied research part of the Cytospora canker management program in collaboration with Jane Stewart of the Department of Agricultural Biology.

According to Minas, one of the trickier aspects of rootstock research and implementation in the orchard is that older rootstocks create and maintain their own microbiome. This can be problematic when introducing new plants into an orchard with an established microbiome of 20 or more years. This can prevent growers from establishing new crops, but rootstock research can provide solutions.

“I think this research combines good science, but also very applied research for the industry,” says Minas. “It’s very much-needed information. We are designing the next generation peach orchard. The potential is 2,000 trees per hectare with the potential of about 40 tons per-acre, which is three times more than what growers are producing.”

Cold hardiness and orchard factors

Of course, being a Rocky Mountain state, Colorado also has to deal with extreme freezing events. For instance, Minas and his team have concluded that a detrimental freezing event occurs when the temperature drops below 25-degrees Fahrenheit for more than 30 minutes. This past April, Colorado peach crops were exposed to almost two hours of temperatures below 25, which obliterated an estimated 90%bof crops. One solution to counter that, according to Minas, is researching late-blooming varieties, but with a short growing season, there’s a balance at play.

“We are doing a lot of research to identify cultivars that are more resilient,” said Minas. “We also can sense with very high precision the freezing of buds. So, we can estimate lethal temperatures that are critical for the growers to make frost-controlled decisions.”

While rootstock and cold hardiness research is critical to the production of peaches, there are many other orchard factors that impact fruit quality. Other factors are myriad, including cropping systems, draining systems, canopy architecture, fertilization, irrigation, cultivars—the list goes on.

“We want to know how to best manage the orchard in order to produce the highest-quality fruit in order to keep the Colorado peach industry’s position in the market,” said Minas.

Minas’ Pomology Program has developed highly accurate models, so with a single scan of fruit, they can predict maturity status, sugar content, and more. Essentially, they can scan entire canopies and get data sets on how different pre-harvest factors impact quality. All of this builds up to the goals previously mentioned: Increase production of delicious Colorado peaches.

“Colorado peaches are the most expensive in the world because of their superior quality that consumers are able to identify – coloration, aroma and sugars,” said Minas. “We want to make sure that all these new introductions in order to improve productivity will not negatively affect current quality—or maybe they’ll even improve the quality.”

To learn more about Minas’ Pomology Program and its research, visit its landing page here.

Christopher Staten, Colorado State University

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