Some Grapefruit Showing Less HLB Symptoms

Daniel CooperGrapefruit, Rootstocks, Varieties

A recent update of the U.S. Department of Agriculture Multi-Agency Coordination (MAC) Project evaluating multiple grapefruit varieties on different rootstocks reveals that some combinations have less HLB symptoms than others. Jackson has one of the lowest ranks for disease index across the combinations. The healthiest trees in the trial include: At least half of the blocks in the MAC trial …


Standing Up Against Hurricanes

Daniel Cooperhurricane, Research, Rootstocks

By Ute Albrecht, Bo Meyering, Carol Tardivo, Gabriel Pugina and Kim D. Bowman The approaching hurricane season poses the question of why strong winds cause some citrus trees to topple over while others remain firm in the ground. Grove location, grove topography and soil type are factors that influence a tree’s ability to withstand tropical-force winds. The tree’s root structure …

ReMedium TI®

Rootstocks and OTC

Daniel CooperHLB Management, Rootstocks

The University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) Citrus Research and Education Center hosted a May OJ Break educational seminar. Ute Albrecht, UF/IFAS associate professor of plant physiology, spoke during the event and gave an update on oxytetracycline (OTC) therapies being applied in citrus groves over the past two seasons. She gave a summary of research she …


Georgia Research Projects Underway

Daniel CooperGeorgia, Rootstocks

Jake Price, University of Georgia (UGA) county Extension coordinator, recently provided a summary of citrus projects he has been working on: Source: Georgia Citrus Association Sponsored Content5 Facts About Fire Ants and How to Control ThemApril 30, 2024BRAZILIAN RESEARCH RESULTS IN A UNIQUE PRODUCT FOR HLB MANAGEMENTApril 1, 2024Protect Your Groves From Citrus LeafminerMay 29, 2023


In Georgia Owari Trial, Yields Peaked in 2021

Daniel CooperGeorgia, Research, Rootstocks

University of Georgia Extension agent Jake Price recently summarized yields for three recent seasons from Owari satsuma trees in a rootstock trial. Last year, 2023, was the last harvest year for data collection in the trial. Price reported that yield in the trial plot peaked in 2021 with a yield of about 20,300 pounds on 60 trees, which would be …


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

Daniel CooperCitrus 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 …


New Results From Owari Rootstock Trial

Daniel CooperGeorgia, 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 …


Rootstocks and More Showcased at Field Day

Daniel CooperEvents, 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 McGillCold 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 McGillEvents, 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 McGillNutrition, 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 McGillCalifornia 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 McGillRootstocks, 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 McGillBreeding, 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 McGillResearch, 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 McGillRootstocks, 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 McGillfreeze, 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 McGillNutrition, 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 McGillEvents, 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 McGillResearch, 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 …