rootstock

New Results From Owari Rootstock Trial

Daniel Cooper Georgia, Rootstocks

By Jake Price Rubidoux is considered the standard rootstock for Georgia, but it was not obtainable from U.S. Department of Agriculture (USDA)-certified nurseries in Florida in 2014 and 2015 because it is not a rootstock used in Florida. It is a proven rootstock in Georgia known for cold hardiness but did not perform well in a multiyear trial. The chart shows …

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Rootstocks and More Showcased at Field Day

Daniel Cooper Events, Rootstocks, Varieties

In early December, the U.S. Department of Agriculture-Agricultural Research Service (USDA-ARS) hosted its annual A.H. Whitmore Foundation Farm field tour and variety display in Groveland, Florida. The event was well attended and showcased the USDA-ARS citrus scion and rootstock breeding program. Attendees loaded up for a hayride and guided tour through the grove. One stop showcased the cooperative work the …

Rootstocks Influence Cold-Hardiness of Georgia Tangos

Josh McGill Cold Hardy, freeze, Rootstocks

Since the Christmas freeze of 2022, University of Georgia Lowndes County Extension Coordinator Jake Price has been conducting cold-hardiness ratings to see how Georgia citrus varieties were influenced by their rootstocks. He focused on Tango performance in a recent report and declared US-1516 “the clear winner” in providing cold-hardiness. Since January of 2023, Price has conducted ratings on how much …

Millennium Block Varieties Tour

Josh McGill Events, Rootstocks, Varieties

Citrus growers are invited to tour the 20-acre Millennium Block at the University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) Indian River Research and Education Center (IRREC) in Fort Pierce on Nov. 7. The tour will be held from 9 a.m. to 2 p.m.  New varieties in the grove are in their fourth year of growth. Researchers are …

Breeder Advice on Nutrition, Scions and Rootstocks

Josh McGill Nutrition, Rootstocks, Varieties

Citrus breeder Jude Grosser recently shared tips on tree nutrition and discussed some scion/rootstock combinations that should work well for trees producing juice oranges. NUTRITIONGrosser became very interested in citrus nutrition several years ago in an effort to keep his newly bred trees healthy in the face of HLB. The University of Florida Institute of Food and Agricultural Sciences professor …

California Lemon Rootstock Research Reported

Josh McGill California Corner, lemons, Rootstocks

Researcher Glenn Wright recently reported how various rootstocks for lemon trees producing fresh market fruit compared for yield and other qualities in three California locations with different climates. Wright is a University of Arizona associate professor and Extension specialist for tree crops. SANTA PAULASanta Paula’s warm summer Mediterranean-like climate had the following results: LINDCOVEResearch in Lindcove, a hot summer Mediterranean-like …

Citrus Breeding Efforts to Solve the Brix Crisis

Josh McGill Rootstocks, Varieties

By Jude Grosser, Maria Brenelli, Ling Liu, Yu Wang and Fred Gmitter The combination of HLB and hurricane Ian have made this a disastrous year for Florida citrus, drastically reducing the quantity and quality of processing oranges. Brix values are the lowest in history. Early-season Hamlin juice with inferior quality is generally blended with late-season Valencia to achieve the target …

USDA Citrus Breeding Program Focused on Rootstock and Variety Solutions

Josh McGill Breeding, Rootstocks, Varieties

The U.S. Department of Agriculture’s (USDA) U.S. Horticultural Research Laboratory in Fort Pierce, Florida, has been home to a citrus rootstock and variety breeding program for many years. Kim Bowman, a research geneticist, has been with the program for more than 30 years. More recently, Matthew Mattia, a geneticist, joined the breeding team. They provide an update on the program …

Millennium Block and MAC Project Updates

Josh McGill Research, Rootstocks, Varieties

Hurricanes Ian and Nicole in 2022 caused early fruit drop in the Indian River area, where two studies of 39,000 trees that might tolerate HLB are being conducted. Researchers now expect significant data from the studies will come after the 2023, 2024 and 2025 season harvests, but they have already gained some insights from the projects.  The first experimental grove, …

Valencia on US-942 Rootstock Is Favored Florida Tree

Josh McGill Rootstocks, Varieties

For at least the last four years, the Valencia SPB-1-14-19 orange has been the most-produced citrus variety in Florida, and US-942 has been the favored rootstock. So, it makes sense that the Valencia SPB-1-14-19 on US-942 rootstock has been the most-produced tree combination for four years running. That information was provided at April’s Florida Citrus Growers’ Institute in Avon Park …

Rootstock Influences Cold-Hardiness in Sugar Belles 

Josh McGill freeze, Mandarins, Rootstocks

Sugar Belles on four different rootstocks in Georgia showed different levels of damage from the December 2022 freeze, reported Jake Price, Lowndes County Extension coordinator for University of Georgia Extension. The Sugar Belles at a Valdosta research plot planted in 2018 have put on the first flush of foliage after being mostly defoliated. The trees are snuggly located between windbreaks …

Nutrient Uptake Potential of Rootstocks

Josh McGill Nutrition, Rootstocks

The objective of a new study published in HortScience was to evaluate and understand the nutrient uptake potential of citrus rootstocks. Conducted by University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) researchers, it is one of the first citrus studies to report nutrient uptake efficiency and the potential of rootstocks. The information presented in the study can be …

Touring Trials at the Whitmore Farm Field Day

Josh McGill Events, Rootstocks, Varieties

The A.H. Whitmore Foundation Farm near Groveland, Florida, recently hosted a field day. The event was presented by the U.S. Department of Agriculture (USDA), New Varieties Development and Management Corporation (NVDMC) and the Florida Citrus Research Foundation. The farm opened in 1959. The 400-acre property includes 110 acres of groves on prime citrus land. Some of the state’s most popular …

Growers and Researcher Discuss Millennium Block Trials

Josh McGill Research, Rootstocks, Varieties

Two citrus growers recently explained the benefits to be gained from research at the Indian River Research and Education Center’s (IRREC) Millennium Block in Fort Pierce, and a scientist discussed a grapefruit study there. The IRREC is a University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) facility. The 20-acre block was planted in 2019 to help growers find …

Millennium Block Field Day Gives Growers Firsthand Look at Trials

Josh McGill Events, Rootstocks, Varieties

The University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) Indian River Research and Education Center (IRREC) in Fort Pierce hosted a drive-through field day for attendees to tour its Millennium block. The grove features more than 5,500 2- and 3-year-old trees. A total of 154 new citrus scion/rootstock combinations are included in the research project. The trial has …

HLB Tolerance Data Expected in Early 2023

Josh McGill Rootstocks, Varieties

Conclusive data on trials in the Millennium Block, expected in early 2023, may reveal which of more than 5,500 trees can tolerate HLB, researchers say. The Millennium Block is at the University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) Indian River Research and Education Center (IRREC) in Fort Pierce. IRREC Director Ronald Cave said the 20-acre grove, established …

Citrus Growers Invited to Visit Variety Trial

Josh McGill Events, Rootstocks, Varieties

The University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) Indian River Research and Education Center (IRREC) will host a Millennium Block Variety Trial Field Day on Oct. 19. The event will be held from 9 a.m. to noon. The Millennium Block is at 7850 Pruitt Research Road in Fort Pierce. Registration can be completed online here or by …

Stay Current With Research on Rootstocks

Josh McGill Rootstocks, Tip of the Week

By Jude Grosser The ultimate solution to the HLB problem is having good rootstocks that can mitigate or eliminate the disease’s impacts in any grafted commercial scion. With this, growers could profitably grow any scion, including grapefruit, Hamlin or even Murcott. Thus, rootstock breeding efforts focus on directly screening new rootstock hybrids for their ability to confer HLB tolerance or …

Chinese Rootstocks Show Promise in Australia

Josh McGill 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

Josh McGill 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 …