At UF/IFAS, we are working on finding solutions for Florida’s citrus growers. This is a summary of one project made possible by state legislative funding for the UF/IFAS Citrus Initiative during the 2018-19 cycle. It documents how we are making progress and providing Florida growers with reasonable, pragmatic solutions to successfully grow citrus in the new age of citrus greening.

Researchers: Ute Albrecht, Horticultural Sciences and Rhuanito Ferrarezi, Horticultural Sciences

IMPACT: Florida growers are engaged in replanting thousands of acres of citrus groves. A commercial citrus tree consists of two parts, an above-ground part that bears the fruit (the scion) and a below-ground part that provides the root system (the rootstock). Choosing the right rootstock/scion combination is crucial to success. Traditionally, rootstocks are grown from seed. This research shows that it is more important to select the right rootstock for an environment than it is to worry about how the rootstocks were propagated in the nursery.

The endemic presence of HLB has forced growers to rethink many of their management practices. A UF/IFAS citrus research team is investigating a question growers are asking when deciding on whether the propagation method used to generate the rootstock makes any difference. Rootstocks may be propagated three ways — from seed, cuttings or tissue culture. UF/IFAS plant physiologist Ute Albrecht of Southwest Florida Research and Education Center and colleagues conducted a study to determine whether propagation methods used for rootstocks has an influence on growth of the scion.

The study was conducted in three counties, using Valencia sweet orange scions grafted to eight rootstock cultivars. Measurements of the trees’ height, trunk diameter, and canopy size were collected, and the health of each tree was assessed. Rootstock variety was a much more significant factor in tree growth than the propagation method involved.

As growers are replanting their groves and trees are in short supply, growers should have more confidence in buying rootstocks regardless of whether they are grown from seed or generated by other methods, namely cuttings or tissue culture. This allows nurseries to produce trees in a shorter amount of time and growers to get the desired trees and replant at a faster rate. This is important for the survival of the citrus industry which is suffering from the devastating effects
of Huanglongbing (HLB, a.k.a. citrus greening).

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