Irrigation benefits both newly planted and established peach trees in UGA study

By for CAES News

While peach orchards are a common sight throughout middle and south Georgia — helping the Peach State live up to its name — peach producers need more than just the title to ensure that both long-established groves and newly planted fields are successful.

Dario Chavez and his research team in the Department of Horticulture on the University of Georgia Griffin campus are working to answer that question. Beginning in 2014, Chavez, along with then-graduate student Bruno Casamali, began working on improving Irrigation and fertilization management practices for young peach trees in the Southeastern U.S. after finding there was no up-to-date information available. Traditionally, irrigation management relied solely on rainfall, which is not always predictable.

“People always think the Southeast gets a lot of rain, but the rain we do get is very variable,” said Chavez. “Sometimes you have a lot of rain and other times you go for long periods without it.”

Peach trees are fast-growing, and without rain they will be under stress, which can affect growth, fruit production and fruit quality. Chavez and his team began looking into irrigation versus the industry standard of no irrigation from the time of orchard establishment. The researchers studied two main types of irrigation delivery systems used in fruit production — micro-sprinklers and drip irrigation. Using a supplementary irrigation system from the time of establishment proved beneficial for tree growth, yield and plant-nutrient uptake compared with trees grown without supplemental irrigation. Drip irrigation was found to be more efficient than sprinkler irrigation. 

“Plants are like babies — early growth and care serves them for many years to come,” said Chavez. “We looked at the difference it makes for starting with a new method compared to traditional methods. We found good results in production and yield, plant growth parameters and nutritional uptake. There are myriad differences across parameters between the two.”

Because Chavez and his team began the research project during a severe drought in 2016, it was easy to visually pick out the drought-stricken trees versus the irrigated trees. The team recommends that growers begin irrigating as early as possible, as it benefits the entire orchard. Chavez noted that because periods of drought are becoming more common in Georgia, and not only happening every few years as they did in the past, he recommends that growers have a system in place to supplement watering as needed.

Water is not the only factor when it comes to the early success of establishing new peach trees. Fertilization is also required to give trees a boost in survival. Because fertilizer is one of the higher costs of running an orchard, knowing the exact amount to use can help a grower keep overall costs down. For this portion of the project, Chavez’s team used different ages of fertilizer based on the recommended rate — 200%, 100%, 50% and 25% — over several years to see the impact it had on the nutrients available in the soil, plant and fruit. Their overall goal was to estimate how trees responded to different rates of fertilization.

Research showed that the nutrient concentration, especially nitrogen, for all plant parts (leaves, stems and fruit) did not change significantly based on the amount of fertilizer used.

“Once the plant fulfills the amount of nutrients it needs, it stops taking them in,” said Chavez, adding that he recommends that growers use half of the previously recommended amount of fertilizer and monitoring plant nutrients yearly to help growers to be more cost-effective. He noted that a 50% savings in fertilizer can make a big difference for growers trying to keep orchard operating costs down.

Currently, Chavez and his team are working on long-term studies in the same areas to estimate whether an overall reduction of 50% in fertilizer will affect the orchard growth and production in the long-term compared with standard fertilization. They are also collaborating with Professor George Vellidis at the UGA Tifton campus to design a peach irrigation app, which Chavez hopes to make available to growers by the end of this year. The app was created with funding from the Georgia Specialty Block Grant, the Georgia Agricultural Commission of Peaches and the Georgia Peach Council. It has been tested for the last two years in mature and new orchards, and it is currently being tested with a grower collaborator prior to release.

Beyond irrigation and fertilization studies, Chavez and his research team are working on breeding a new peach cultivar for Georgia. The team is installing greenhouses on the UGA Griffin campus, which will allow the trees to grow normally while they control the growing conditions regardless of weather. This is especially important when cross breeding peach cultivars, as a freeze can destroy the crop, which can be devastating to a breeding program. The greenhouses will allow Chavez’s program to secure breeding populations year after year.

For more information about Chavez’s research program, visit site.caes.uga.edu/chavezlab.

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