CITRUS NURSERY SOURCE: A Day of Learning About New Rootstocks and Varieties

Daniel Cooper Citrus Nursery Source, Rootstocks, Varieties

By Peter Chaires

The U.S. Department of Agriculture-Agricultural Research Service (USDA-ARS) U.S. Horticultural Research Laboratory and Florida Citrus Research Foundation (FCRF) jointly held an open house, variety display and field tour at the W.H. Whitmore Foundation Farm between Leesburg and Groveland in early December.

This annual event provides a great opportunity for industry members to see the latest innovations in USDA-ARS research, taste and score citrus and avocado selections, and tour the farm. The farm tour makes stops at key research projects, each offering a narrated overview and time for questions. As projects are concluded at the farm, they are soon replaced with new projects, ensuring an interesting and productive trip for all. This fantastic event was co-sponsored by Florida Citrus Mutual and Wedgworth’s Inc. Here are some highlights from this year’s event:


Attendees were informed about the seed source block where promising and popular citrus rootstock trees are grown, many of which are just now coming into production. Phillip Rucks, FCRF chairman and owner of Phillip Rucks Citrus Nursery, spoke at the stop. US-942 seed trees are coming into heavier production this year, as are the US-812 trees. USDA SuperSour rootstock trees and UFR rootstock trees will be producing seed soon.

Kim Bowman showed attendees some of the rootstock selections he’s been developing over the past two decades.
Photo by Frank Giles

Kim Bowman, USDA-ARS research geneticist, highlighted the results from the first 18 months of a rootstock trial, using Hamlin sweet orange as the scion.


Bowman highlighted the results from a rootstock trial in its fourth year, using the University of Florida Institute of Food and Agricultural Sciences Bingo mandarin as the scion. The trees looked good and exhibit tolerance to HLB, but small fruit size remains a challenge.


This stop featured the Donaldson tree, which has been the focus of much interest due to its apparent tolerance to HLB. From this tree, the Florida Department of Citrus (FDOC) and Florida Department of Agriculture and Consumer Services launched the Expedited Budwood Increase Program to ensure rapid availability of plant material for nurseries interested in growing Donaldson and four additional promising orange varieties.


Matt Mattia, USDA-ARS plant geneticist, informed attendees about his mandarin scion trial. New selections showing promise are being studied in additional detail in this trial location. Several mandarins were featured in the variety display for sampling.


I was happy to provide an overview of the purpose of the Whitmore Variety Demonstration block. This small block contains commercially available scions, each on two popular rootstocks. Trees in this block are 2 years old and should be producing a crop next year. Growers, processors and packers will be able to visit, observe horticultural performance and sample fruit by appointment. Additional trees are ready for planting in the block this spring.

Also at this stop, Brite Leaf Citrus Nursery owner Nate Jameson and grower Bill Lennon provided an overview of the new deep well and irrigation system. This new system will help provide expanded irrigation coverage and freeze protection on the farm. Thanks to Sen. Ben Albritton (FL-27), Florida Citrus Mutual, the Florida Legislature and the FDOC for making this needed irrigation expansion possible.


The Scion Breeding Demonstration is where it all starts. Closely spaced trees, each a unique creation, can be observed for growth and tolerance to HLB. From this collection, scions will be identified for replicated trials. There are thousands of unique varieties in this block.


After the tour was complete, attendees were treated to extensive citrus and avocado fruit displays. Citrus included orange-like selections for processing, mandarins, grapefruit and grapefruit hybrids for the fresh fruit market. The icing on the cake was a wonderful barbecue lunch provided by Florida Citrus Mutual.

After the tour, attendees were treated to a citrus fruit display.
Photo by Frank Giles

The A.H. Whitmore Foundation Farm is a long drive for some, but as those in attendance will attest, it is a day well spent. Watch for the announcement and plan to attend the event next December.

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

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