Plant breeders Fred Gmitter and Jude Grosser report on their efforts to develop rootstocks that perform well in Florida from several perspectives. In addition to seeking tolerance to HLB, they are working on rootstocks that might control tree size, deal with other diseases and pests and perform in a range of soils. Gmitter and Grosser are University of Florida Institute …
Rootstocks US-812, US-942 Hold Promise
The rootstocks US-812 and US-942 seemed to offer promise in early economic performance evaluations that economist Ariel Singerman discussed at the 2021 Citrus Expo. Singerman is a University of Florida Institute of Food and Agricultural Sciences Extension economist at the Citrus Research and Education Center in Lake Alfred. Singerman analyzed yield and economic performance of rootstocks in commercial settings during …
The Secret Ingredient of Developing New Citrus Rootstocks
By Bill Castle Creation, evaluation, release and commercial acceptance are dynamic, interactive activities that together constitute new rootstock development. Underpinning each of them is a commonly overlooked and rarely mentioned activity, professional judgment. Yet, it is something everyone has and recognizes as getting better with time and experience. It is a skill developed and refined over time from knowledge of …
CRDF Selects Rootstocks for Trials
The Citrus Research and Development Foundation (CRDF) directors recently ratified the rootstock selections for the planned rootstock field trials and discussed the organization’s involvement in future research, CRDF Chief Operating Officer Rick Dantzler reported. The board ratified 10 rootstock selections for the new field trials, overseen by CRDF’s Select Committee on Plant Improvement. According to Dantzler, the field trials will evaluate …
Citrus Nematode and Resistant Rootstocks
University of Florida Institute of Food and Agricultural Sciences professor Larry Duncan discussed the citrus nematode (Tylenchulus semipenetrans) during a recent international webinar on plant parasitic nematodes hosted by ADAMA. T. semipenetrans has a worldwide geographical distribution, making it the most common plant parasitic nematode of citrus. According to Duncan, this pest is regulated by seasonal carbon flux in fibrous …
Varieties and Rootstocks Reviewed
In his virtual Citrus Expo presentation, Jude Grosser reviewed varieties and rootstocks showing promise for productivity in the face of HLB. Grosser is a University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) plant breeder. His presentation was based on work done by him and fellow UF/IFAS researchers Bill Castle and Fred Gmitter. Grosser said UF/IFAS released OLL-20 “based …
New Rootstocks in the Citrus Breeding Pipeline
By Jude Grosser, Fred Gmitter and Kim Bowman Two citrus breeding programs have identified several rootstocks that can currently be planted with confidence when combined with appropriate scions, including mid- and late-season oranges, and grown with emerging enhanced nutrition programs. These citrus breeding programs are at the University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) Citrus Research and Education …
Nutrition and Rootstocks to Be Studied
Seventeen researchers have responded to the Citrus Research and Development Foundation’s (CRDF) request for very specific citrus nutrition research, the organization’s board of directors learned May 19. CRDF Chief Operating Officer Rick Dantzler said several advisory groups will review the proposals prior to the CRDF board choosing and funding selected proposals no later than September. The research requested by CRDF …
Advice on Picking Rootstocks
Growers who attended a recent Citrus Research and Development Foundation (CRDF) rootstock field day in Highlands County should look at similar CRDF trials when deciding what rootstocks to plant. That’s the opinion of Jim Graham, a CRDF project consultant who spoke at the event last month. The same six rootstocks with Valencia scions that are in field trials in Highlands …
USDA Releases 3 New Citrus Rootstocks
The U.S. Department of Agriculture has released three new citrus rootstocks that are available for unrestricted public use. The rootstocks are US SuperSour 1, US SuperSour 2 and US SuperSour 3. A new publication provides summary information about the new releases. Get the new publication here: Sponsored ContentTake Advantage of Rising Temperatures to Treat for Fire AntsJuly 1, 2025Take the …
Field Testing of New HLB-Tolerant Scions and Rootstocks
By Rhuanito S. Ferrarezi, Jude W. Grosser, Fred G. Gmitter, Ed Stover and Kim Bowman Citrus is Florida’s most important agricultural commodity. The state produces citrus for different markets: round oranges for juice; navels, mandarins, grapefruit and lemons for the fresh-fruit industry; and lemons for extracting peel oil for processing. Huanglongbing (HLB) disease affects all citrus varieties. Since the discovery …
Some Rootstocks Succumbed to Irma
Researchers inspecting their groves at the Southwest Florida Research and Education Center after Hurricane Irma found that trees on certain rootstocks were very likely to be uprooted. Fernando Alferez, a horticulturist at the Immokalee center, discusses the uprooted trees and hopes he has for fresh citrus growing. “This is anecdotal evidence from our experience here,” Alferez says. “What we saw …
Rootstocks and HLB Tolerance — Another Perspective
By Ute Albrecht Tolerance to a disease is generally defined as the ability to be productive in the presence of disease-causing organisms. This is contrary to resistance, which is defined as the ability to completely evade a pathogen due to specific resistance mechanisms. The question as to what defines an HLB-“tolerant” rootstock was posed in an article by Bill Castle, …
Field Trials of Rootstocks and Scions: What Can They Tell Us?
By Harold Browning Column sponsored by the Citrus Research and Development Foundation Plant breeding programs have been a mainstay of citrus production worldwide. They have served as a basis for gradual improvement in fruit quality, adaptability to varying growing environments, and most importantly, to disease management. For that reason, new germplasm has been a front line of pursuit in the …
HLB and ‘Tolerance’ as a Practical Matter in Choosing Rootstocks
By Bill Castle (Editor’s note: Click on the graphs throughout the article to enlarge them.) By classic biological definition, a particular citrus rootstock-scion combination when infected with Candidatus Liberibacter asiaticus (CLas) would be considered tolerant if infected trees had no more than slight reductions in performance, sometimes accompanied by a reduced level of the pathogen. That definition implies that the …
Florida CUPS: From a Small Plot of Potted Plants to 1,500 Acres
When University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) Professor Arnold Schumann started a citrus under protective screen (CUPS) plot in Florida in 2014, the grapefruit trees were in above-ground pots. The plot at the Citrus Research and Education Center was on 1.33 acres that included 1 acre of planted citrus. After five years, the grapefruit trees on …
Extensive Educational Opportunities at the Citrus & Specialty Crop Expo
The Citrus & Specialty Crop Expo is fast approaching. During the July All In For Citrus podcast, Tripti Vashisth, University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) associate professor, discussed the extensive citrus seminar program scheduled for Aug. 20–21 at the Florida State Fairgrounds in Tampa. The citrus sessions will include more than 20 speakers over the course …
Cold-Hardy Citrus Growers Should Consider Multiple Varieties
By Clint Thompson and Dale Sandlin The potential lack of satsuma mandarins this season in the cold-hardy citrus region should not discourage growers from adding to their production portfolio in the future. It just means they need to try other varieties, despite satsumas being the most commonly produced variety in the region. Jake Price, University of Georgia (UGA) area citrus …
Two Genome-Edited Trees Are Approved
Two non-transgenic genome-edited orange plants — a Hamlin and a Valencia that may resist HLB — have been federally approved and are ready for Florida growers. Nian Wang, University of Florida Institute of Food and Agricultural Sciences eminent scholar endowed chair in biotechnology, reported this news in a June 17 virtual presentation. The plants, which Wang termed “Eds1-edited,” have received …
CRAFT Continues to Push New Plantings and HLB Therapies
During the recent Florida Citrus Industry Annual Conference, Steven Hall provided an update on the Citrus Research and Field Trial (CRAFT) programs. Hall is executive director of the CRAFT Foundation. CRAFT programs have been very popular among growers to incentivize new plantings and build knowledge about HLB therapies like trunk injection, the use of individual protective covers, plant growth regulators …