Planting-density and nutrition trials in the Indian River area were among the topics discussed at the Florida Citrus Show earlier this year. The presenter was Rhuanito “Johnny” Ferrarezi, a University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) researcher at the Indian River Research and Education Center.
A grapefruit planting-density trial utilized a staggered diamond set to maximize trees per acre on the bedded groves found in the region. Ferrarezi reported on a planting of 393 trees per acre for the trial. “We squeezed in more trees to the acre, and what we are seeing is a great increase in fruit yield over a period of six years,” he says. Ferrarezi adds that researchers want to continue the trial to “see the effect of the competition for light, water and nutrients on tree yield over time.”
He reports that fruit quality also improved. “We were able to increase Brix with higher tree density,” he says. “If we can produce more fruit of better quality, we are actually succeeding in staying in business while we are trying to figure out a solution for HLB.”
In a grapefruit nutrition trial, using higher levels of micronutrients than UF/IFAS recommends did not increase yield. “We were expecting to see positive results by using more nutrients,” Ferrarezi says. “In grapefruit, that didn’t prove correct yet.” But, he says “it takes several years for trees to respond … We do believe that proper nutrition is the key to keep growers productive.”
Ferrarezi reports on a sweet orange planting-density trial that included the use of fertigation for application of nutrients. “Here at the River, some higher-density orange trees planted under fertigation … really maximized tree yield,” he says. “We do have one commercial grower that actually started planting oranges and got rid of all his grapefruit in an attempt to continue producing citrus here at the River.” That’s intriguing, since the Indian River region is recognized worldwide for its grapefruit.
Hear more from Ferrarezi:
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