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 …

citrus

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 …

rootstock

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 …

field

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 …

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 …

Trunk Injection: Rootstock vs. Scion

Josh McGillHLB Management, Tip of the Week

By Ute Albrecht, Larissa Nunes and Gabriel Pugina   The current label recommends trunk injection of oxytetracycline (OTC) into the rootstock, but this may not always be possible. Previous University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) studies have shown that both rootstock and scion injections are effective. However, researchers have not yet studied if different rootstocks influence …

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 …

grapefruit

Grapefruit Rootstock/Scion Research Update

Josh McGillGrapefruit, Indian River, Research

University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) researchers Mark Ritenour and Flavia Zambon recently provided an update on a large field trial. The project is called Evaluation of Potential HLB Tolerant Grapefruit Rootstock/Scion Combinations in the Indian River District of Florida. A summary of their update follows:  The project started as a collaborative effort between the UF/IFAS …

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 …

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 …

Stay Current With Research on Rootstocks

Josh McGillRootstocks, 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 McGillInternational, 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 McGillHLB 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

Josh McGillRootstocks, 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

Josh McGillLimes, 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 …

Progress With SuperSour Rootstock Trials

Josh McGillResearch, Rootstocks

By Kim D. Bowman The breeding of new citrus rootstocks is not an endeavor for the impatient. Two of the most popular rootstocks in Florida, US-942 and US-812, each were included in field evaluation for more than 20 years before the U.S. Department of Agriculture (USDA) released them for commercial use. In these cases, the time invested in thorough testing …

Australia Evaluating Dwarfing Rootstocks

Josh McGillInternational, 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 …