The Florida citrus soil water atmosphere plant (SWAP) project: final summary of cumulative yields and tree health

Leon Hartwell Allen, David V. Calvert, Mortimer Cohen, Robert R. Pelosi, James S. Rogers, Ernest H. Stewart


The Florida Citrus Soil Water Atmosphere Plant (SWAP) Project was initiated by applying three soil tillage (mixing) treatments: shallow tillage (ST), deep tillage (DT), and deep tillage plus lime (DTL) to nine blocks on a Spodosol (Oldsmar fine sandy loam) at the University of Florida Indian River Research and Education Center. Each block had six subsurface plastic drain lines, three adjacent drains were submerged and three adjacent drains were open. ‘Pineapple’ sweet orange and ‘Marsh’ grapefruit scions on six rootstocks were transplanted from the nursery in November 1970. Yields were measured from 1973–74 to 1984–85 by scion, rootstock, tillage treatment, subsurface drain type, and replication. At the end of 12 harvests, cumulative yields of ‘Pineapple’ orange were greatest for rough lemon, Rangpur lime, and Cleopatra mandarin rootstocks, intermediate for sour orange and Carrizo citrange, and lowest for Poncirus trifoliata rootstocks. The last survey of tree health was conducted in November 1984. The healthiest trees were on Cleopatra mandarin rootstock. Rough lemon had the most trees with blight symptoms. Sour orange had the most trees with Tristeza. Rangpur lime and rough lemon had some foot rot. Carrizo citrange and Poncirus trifoliate had the most water damage symptoms. Yields were related to tree health.

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Proc. Fla. State Hort. Soc.     ISSN 0886-7283