Monitoring tree nutrient content via sap analysis is a fairly new concept in Florida citrus, but has at least a decades-long history in other crops. That history and other background information about the technique were addressed in a recent University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) virtual seminar. The workshop’s purpose was to introduce Florida’s citrus growers to the technique, according to host Rhuanito “Johnny” Ferrarezi, a UF/IFAS researcher.
George Hochmuth, UF/IFAS emeritus professor, kicked the workshop off with a report on his research of the nutrient detection technique related to vegetables in the 1980s. He reported that vegetable growers who had started using fertigation wanted an inexpensive and quick test for nutrients as an alternative to tissue testing.
Hochmuth defined sap as “the juice you squeeze out of the petiole of the plant.” The petiole is the stalk attaching the leaf blade to the stem.
Sap analysis isn’t meant to replace standard lab analysis for nutrient content, but may reduce the amount of standard lab analysis, Hochmuth said.
Retired Cornell University researcher Michael Rutzke said objectives of sap analysis include determining the nutrient status of plants – and making nutrient corrections – before symptoms of problems occur. A slide he showed stated that more research is needed “to correlate between traditional method and juice/sap method for all crops of interest.”
Scott Wall, founder and CEO of New Age Laboratories, said sap analysis offers detection of nutrient deficiencies or excesses from four to six weeks earlier than dry tissue analysis.
Jeff Glass, business development manager with Agro-K, said tissue testing looks backward while sap analysis looks forward. A slide he presented stated that it “reveals nutritional imbalances before they appear visibly.”
Apple growers have used sap analysis and benefited from it for years, said Nathan Harman, a consultant with AEA. “I want citrus growers to have access to that,” he said.
Workshop host Ferrarezi is initiating sap analysis research for citrus in Florida’s Indian River region.
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