Chinese Rootstocks Show Promise in Australia

Jim Rogers International, Research, Rootstocks

Preliminary data from an Australian research project suggest Chinese rootstocks No. 24 and 85-24 are having a dwarfing effect on citrus tree growth and will be candidates for future high-density cropping systems. Citrus Australia reported that those rootstocks have strong potential in heavy soils, and that results on deep sandy loam soil are also very encouraging. Tahir Khurshid from the …

Progress in Developing Improved Citrus Rootstocks to Mitigate HLB

Jim Rogers HLB Management, Research, Rootstocks

By Jude Grosser, Manjul Dutt and Fred Gmitter Exploiting citrus genetic diversity is the key to defeating HLB. Plant species have survived for millennia with evolving, hostile pathogens. This is possible through natural selection within genetically diverse populations. Tolerant or resistant individuals survive and intermate, get through the bottleneck, and the species evolves. Current citriculture is based on extremely limited …

Releasing Rootstocks: Balancing Responsibility With Urgency

Jim Rogers Rootstocks, Tip of the Week

By Bill Castle, Fred Gmitter and Jude Grosser The rootstock development cycle, from creation to eight years in the field to release, is presently about 10 to 15 years. However, if multiple trials are involved, then the time required is increased. The criteria used to advance new selections through the system are commercially based. Rootstocks for juice fruit are assessed …

Rootstocks and Fertilization for Finger Limes

Jim Rogers Limes, Nutrition, Rootstocks

Rootstock selection and fertilization are important for those considering growing finger limes in Florida. University of Florida Institute of Food and Agricultural Sciences horticulturist Tripti Vashisth addressed both of those topics in a recent virtual Finger Lime Symposium. Vashisth concluded that Volkamer lemon, UFR-5 and US-802 rootstocks appear promising for finger limes. She noted that a vigorous rootstock influences tree …

Australia Evaluating Dwarfing Rootstocks

Jim Rogers International, Research, Rootstocks

Tahir Khurshid of Australia’s New South Wales Department of Primary Industries (NSW DPI) is leading a project evaluating several overseas rootstocks budded to a range of mandarin and sweet orange varieties. One of the components is evaluating the rootstocks for their dwarfing effect, which will potentially produce small trees for high-density planting systems for the citrus industry.   Size-controlling rootstocks have …

citrus rootstock

Florida’s Top Rootstocks and Varieties

Ernie Neff Rootstocks, Varieties

US-942 remained the top citrus rootstock in Florida for the third year in a row, and Valencia SPB-1-14-19 was the top variety. ROOTSTOCKSMore than 1.28 million nursery trees were budded on US-942, according to the Florida Department of Agriculture and Consumer Services’ (FDACS) Citrus Budwood Annual Report for 2020-21. The next 14 most popular rootstocks, with the number of buddings, …

Early Performance of Orange Rootstocks in Commercial Settings

Tacy Callies Economics, Rootstocks

By Ariel Singerman, Stephen H. Futch and Brandon Page This article provides estimates on the performance of different rootstocks grafted with Valencia sweet orange scions in commercial field conditions. These are the first estimates obtained from side-by-side trials that compare the performance of rootstocks developed by two breeding programs: The University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) …

Australia to Test UF’s HLB-Tolerant Rootstocks

Ernie Neff Rootstocks

HLB-tolerant rootstock seeds from the University of Florida (UF) have arrived in Dareton and Bundaberg to be evaluated under Australian conditions. Citrus Australia CEO Nathan Hancock said it’s important that the rootstocks have arrived in Australia well before the Asian citrus psyllid (ACP) and the HLB it spreads. “We need to know if these rootstocks from Florida are going to …

Research on Rootstocks: More Than HLB

Ernie Neff Rootstocks

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

Ernie Neff Rootstocks

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

Tacy Callies 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

Tacy Callies CRDF

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

Tacy Callies Pests

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

Ernie Neff Rootstocks, Varieties

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

Tacy Callies Research, Rootstocks

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

Ernie Neff Nutrition

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

Ernie Neff 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 …

citrus rootstock

USDA Releases 3 New Citrus Rootstocks

Daniel Cooper 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:

Field Testing of New HLB-Tolerant Scions and Rootstocks

Tacy Callies Research, Rootstocks, Scions

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

Ernie Neff hurricane, Rootstocks

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 …