Editor's note: A special thanks to Dr. Monica Ozores-Hampton at the Southwest Florida Research and Education Center for coordinating The Immokalee Report, of which the article below is part.
Maury Boyd’s Orange Hammock citrus grove has become well known to the Florida citrus industry and to international citrus-growing regions because of his use of foliar fertilizer nutrients and SAR (systemic acquired resistance) products to maintain the health of huanglongbing-infected trees.
The Florida Department of Agriculture, Division of Plant Industry, positive identified HLB in Boyd’s grove using PCR (polymerase chain reaction) in spring 2006. Since HLB confirmation, the Orange Hammock grove has maintained tree health and yields, producing seven years of profitable crops.
The production program consists of a foliar spray cocktail of nutrients and SAR products applied three times per year with the initiation of vegetative growth flushes in spring, summer and fall.
Combined with an Asian citrus psyllid insect management program, the foliar spray cocktail has helped reduce and ameliorate HLB leaf symptoms. This, and a good soil-applied dry fertilizer program, has allowed the trees to remain healthy and productive.
The psyllid insecticide management program is applied by fixed-wing aircraft using low volume of 5 to 10 gallons per acre. The applications are timed every five to six weeks during the growing season.
The products in the foliar-applied nutrient/SAR cocktail and ground fertilizer are given in Table 1. Agri-Pro is a humic acid product containing small amounts of many minerals, including nickel, which is a required nutrient for citrus and usually available in nature.
More about the Orange Hammock grove
The Orange Hammock grove in Felda, planted in 1992, is a typical bedded flatwoods grove with 165 trees per acre of Hamlin and Valencia sweet oranges on Swingle citrumelo and Carrizo citrange rootstocks. It is irrigated with micro-sprayers.
The grove is now 95 percent infected with HLB. In 2012, the overall severity of tree disease was rated less than in previous years.
Yields from the grove were collected from the grower records. The combined yield and juice quality by variety for seasons 1999-00 to 2011-12 is given in table 2. All fruit yield is reported as 90-pound boxes per acre and mean pound solids per box.
The mean yield of the six years before HLB for Hamlin was 569 boxes per acre. After finding HLB, it has been 576 boxes per acre.