Tacy CalliesCitrus Nursery Source

By Peter Chaires

citrus nursery
The annual field day at A.H. Whitmore Foundation Farm in Groveland allows growers to view citrus rootstocks and varieties.

Beginning this month, Citrus Nursery Source (CNS) transitions to Citrus Industry magazine after 14 years in Florida Grower magazine. For those unfamiliar with this column, CNS covers citrus industry issues that are of potential interest to nurseries and the growers they serve. Recognizing that it is difficult for nursery owners and staff to regularly attend meetings, this brief monthly column intends to elevate awareness of subjects that may warrant additional study or consideration.

Citrus rootstock seed availability is essential for Florida’s future citrus tree production. Growers are ordering liners produced from tissue culture, but some nurseries and growers show a preference for liners produced from seed. Seed of some prime citrus rootstock varieties, including US-812, US-942, US-802, US-897, C-54, C-57 and C-146, have been in short supply in years past.

To serve the future needs of the industry, the Florida Citrus Research Foundation (FCRF) and U.S. Department of Agriculture-Agricultural Research Service (USDA-ARS) teamed up starting in 2018 through 2020 to plant a larger rootstock seed production block of improved HLB-tolerant varieties.

As the trees mature, production from the A.H. Whitmore Foundation rootstock seed production block is increasing to meet the demand of the citrus industry. Table 1 shows the production of selected varieties over the past three years. The US-942 supply is increasing quickly. C-54, C-57, C-146, some UFRs and SuperSours have also been planted at Whitmore and are making progress. Attendees at last month’s USDA-ARS A.H. Whitmore Foundation Farm Field Day and Farm Tour got a glimpse of the new plantings.

Existing 12-year-old seed trees of US-802 and US-897 have an abundance of fruit along with the younger plantings. Barring tree-damaging freezes, the Whitmore seed production block productivity should increase again in 2024.

The FCRF board of trustees and USDA-ARS annually review the list of rootstock varieties included in the block. Understanding that rootstock production can’t turn on a dime, it takes time to propagate trees, plant them in the block and generate fruit for seed extraction. Lacking a crystal ball, this group seeks to identify consistent commercial demand trends, thereby ensuring that grower and nursery needs will be met, and valuable space and farm resources will not be committed to rootstocks that have niche appeal or that lack substantive grower support. Rootstocks that cannot be reliably or efficiently produced from seed, or rootstocks that appear to be produced in sufficient quantities in other public or private seed blocks, may not require inclusion.

The Citrus Research and Education Center in Lake Alfred will host two more fruit displays this season. The events will take place at 1:00 p.m. on Jan. 23 and Feb. 21. These two displays tend to be heavy on oranges, orange-like fruit and grapefruit. Attendees can sample fruit and offer input to help inform University of Florida citrus breeder decisions. When sufficient fruit volume is available, juice samples of new selections, industry standards and interesting blends are presented.

These events are also an excellent opportunity to remain current on the latest developments in citrus plant improvement and what is and may soon be available. For planning purposes, each display takes about an hour to complete. A diverse audience of growers, processors, flavor chemists, packers, marketers and fruit enthusiasts ensure a successful event.

Peter Chaires is executive director of the New Varieties Development and Management Corp.

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