Ongoing citrus rootstock trials being conducted by the University of Georgia (UGA) hold promise for Georgia’s growing citrus industry.
Jake Price, UGA Extension agent and Lowndes County Extension coordinator, has produced six local citrus rootstock/variety trials with varying objectives.
The oldest trial, planted in 2014, is growing Owari satsuma trees on standard and new trifoliate hybrid rootstocks. Each year, as the trees mature, data is being collected to show how each rootstock performs with the Owari satsuma scion. Price gave an update on the ongoing trial during a virtual Georgia citrus meeting, hosted by Fort Valley State University.
Rootstocks being evaluated are US-942, US-897, US-852, US-812, X-639, Kuharski Carrizo, Swingle, Cleopatra, sour orange and Rubidoux. The goal of this replicated trial is to determine which rootstocks perform best with satsumas, in hopes of giving Georgia growers more rootstock options.
Data collected in 2020 from the Owari trial showed that trees on the rootstocks X-639, Kuharski Carrizo, Cleopatra and sour orange produced less fruit in 2020 than 2019, indicating that these trees may alternate bear, meaning they produce greater than average yield one year and lower than average the next year.
Rootstocks US-942, US-897 and US-852 produced significant yield increases over the previous year and have yet to alternate bear. Thus far, Owari trees grafted onto US-942 have produced the most yield in the Owari trial, producing 89 pounds more fruit compared to US-852 in 2020.
Additionally, there was no large bloom in March, and trees bloomed over several weeks.
Price also notes that fruit took longer to turn orange in color on rootstocks with heavier fruit loads, including rootstocks US-942, US-987 and Rubidoux. This can be a problem when marketing the fruit, but each growing season is different, so multiple years of data may be needed to draw a conclusion.
More information regarding Georgia citrus rootstock trials can be found here.
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