Semester of Graduation

Fall 2023

Degree

Master of Science (MS)

Department

School of Plant, Environmental, and Soil Science

Document Type

Thesis

Abstract

Many of the world’s citrus growing regions are experiencing challenges related to citrus greening, also known as Huanglongbing (HLB) caused by the presumed bacterial agent Candidatus Liberibacter spp. HLB is vectored by the Asian citrus psyllid (Diaphorina citri) and through propagation of infected citrus material. HLB impacts tree health as well as fruit development, ripening, and quality of the resulting citrus fruit, often leading to an unmarketable product. Producers are growing citrus in high density orchards underneath protective screening material that excludes the Asian citrus psyllid, preventing new HLB infections. Four ultra-high containerized tree spacings of 2 feet (0.61 m), 3 feet (0.91 m), 5 feet (1.52 m), and 7 feet (2.13 m) were studied using ‘Owari’ satsuma mandarins (Citrus unshiu Yu.Tanaka ex Swingle, Marcow) budded to the dwarfing ‘Flying Dragon’ rootstock (Poncirus trifoliata L. Raf.) beginning in September of 2021.

Growth indexes including height, width, and trunk caliper, fruit count, weight, brix, blossom count, and grade were measured. For all tree spacing densities, it was found that growth and fruit quality as well as total yield did not differ among the density treatments in the containerized orchard. These findings indicate containerized satsuma mandarin producers may maximize spacing within the protective screened environment using ultra high-density stocking rates. Early production after establishment of this orchard system also offers a potential increased return on investment due to fruiting at a much more juvenile stage of development.

Date

11-2-2023

Committee Chair

Kirk-Ballard, Heather

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