Trials yield answers
In August, Arapaho Citrus harvested the fruit early on the Ray Ruby/Flying Dragon and Rio Red trees to give them more time to grow. According to the company’s harvest numbers that are posted online, the yields would have been about 73 boxes per acre for the Flying Dragon rootstock planted on a 6 by 20 row spacing, 92 boxes per acre for the Rio Red rootstock planted on a 8 by 20 spacing, and 121 boxes per acres for the Rio Red rootstock planted on a 6 by 20 spacing. This is using the assumption that the fruit would have averaged a size 40 when mature at about 24 months old.
Spyke says these yields are one or two years ahead of the per acre yields he would expect with trees planted using the modern 10 by 20 row spacing. “The more powerful thing than the amount of fruit you get is the cost. Basically, if you put more trees on an acre, two things happen. First you get more fruit per acre in the early years until the trees form a hedgerow. Second, the cost per box of fruit is less because when you mow, spray or do anything you are treating more trees,” he says.
Still in search of answers
Despite its promise, Castle says there are still questions about the system’s viability in Florida. Much of the information on specific fertility needs of trees is still an inexact science, he says, and the information from South Africa is proprietary.
Through test plots and additional research at the Citrus Research and Education Center, Castle says he hopes to eventually develop macronutrient recommendations for Florida citrus.
In addition, trees in these modern high-density orchards will be managed to not exceed 6 to 9 feet tall. Although some over-the-row pruning equipment can be used to manage the high-density hedgerow, Castle says growers will likely need to modify or purchase new over-the-top harvesting equipment. He already has been contacted by at least one equipment manufacturer to explore developing harvesting equipment specific to advanced production systems orchards.