Hamlin

Donaldson: Potential Alternative to Hamlin in OJ

Daniel CooperOrange Juice, Varieties

U.S. Department of Agriculture-Agricultural Research Service (USDA-ARS) scientists are studying the possibility of the Donaldson sweet orange replacing the HLB-ravaged Hamlin in orange juice (OJ). The scientists work at the U.S. Horticultural Research Laboratory in Fort Pierce, Florida. While assessing citrus trees with oranges that might be used for commercial OJ production, the scientists found the Donaldson tree at the …

Hamlin

Apply Brassinosteroids to Improve Hamlin Brix

Daniel CooperHLB Management, PGRs, Tip of the Week

By Fernando Alferez and Divya Aryal Brassinosteroids (BRs) are a class of plant growth regulators with several effects on plant growth and development. University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) work in the last few years has shown that BR treatments may influence internal maturity in Hamlin sweet orange if performed at the right time. Research has …

Build Resilience in HLB-Affected Hamlin Trees

Josh McGillHLB Management, Tip of the Week

By Taylor Livingston and Tripti Vashisth Fighting HLB alongside weather disasters like freezes and hurricanes is leaving growers with little options for sustaining yields. The Hamlin sweet orange variety is known for higher susceptibility to HLB symptoms which cause rapid tree decline, including increased pre-harvest fruit drop and canopy loss. Production strategies that target fruit drop and canopy health improvement …

Gibberellic Acid Shows Promising Results on Hamlin

Josh McGillHLB Management, PGRs, Research

By Tripti Vashisth and Taylor Livingston Grower-led trials in 2022 showed positive results of gibberellic acid (GA) treatment on Hamlin trees in Florida. This article primarily discusses two growers’ trials in detail. Both sites showed improvement in fruit production from the GA application. Many growers have adopted GA applications in the past year as part of their grove management strategy. …

Examining Hamlin Survivor Trees

Josh McGillHLB Management, Research, Varieties

By Gary England, Fred Gmitter and Manjul Dutt In 2014, most groves in Central Florida had citrus greening infection rates approaching 100%, but a Lake County grower reported that some trees in his Hamlin on Swingle blocks seemed to be relatively healthy. Some visual HLB symptoms were observed on these “surviving” trees, but they did not have the massive fall …

Gibberellic Acid Application on Hamlin Appears Promising

Josh McGillResearch

By Tripti Vashisth In a multi-year field trial, University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) researchers have seen beneficial effects of gibberellic acid (GA) on Valencia sweet oranges. Monthly application of GA (September to January) on Valencia improved yield on average by 30%, reduced fruit drop and elicited enhanced plant defense response. These benefits are possibly due …

Parson Brown Outperforming Hamlin

Ernie NeffResearch, Varieties

Manjul Dutt recently discussed his research on the Parson Brown (PB) sweet orange, which shows some characteristics that could make it more attractive than Hamlin, Florida’s leading early-season orange. Dutt is a University of Florida Institute of Food and Agricultural Sciences horticultural sciences researcher at the Citrus Research and Education Center in Lake Alfred. Dutt’s research, funded by the Citrus …

Trials to Seek Hamlin Alternative

Ernie NeffVarieties

Twenty-four citrus scions were approved by the Citrus Research and Development Foundation (CRDF) on March 23 for eventual use in multiple field trials around Florida. The purpose of the trials will be to find an early-season orange that is more tolerant of HLB disease than Hamlin, said CRDF Chief Operating Officer Rick Dantzler. Hamlin has long been the primary early-season …

Rootstock Effects on Valencia and Hamlin in Large-Scale Commercial Plantings

Tacy CalliesResearch, Rootstocks

By Ute Albrecht, Sudip Kunwar and Jude Grosser Prior to 1865, the only rootstocks used in Florida were sour orange and sweet orange. Use of grafted trees instead of seedling trees became necessary because of the devastating effects of phytophthora on sweet orange. Sour orange was widely used as a rootstock because of its resistance to phytophthora and other positive …

Varieties: Replacing Hamlins with Early Valencias

Ernie NeffVarieties

University of Florida/Institute of Food and Agricultural Sciences plant breeder Jude Grosser makes a case for Florida’s citrus industry replacing Hamlin oranges with early-maturing Valencia oranges that he and others are developing. “I think that’s a no-brainer because Hamlins are having a really bad time with greening, and orange juice sales are declining,” Grosser says. “Hamlin is half our juice. …

podcast

All In For Citrus Podcast, January 2026

Daniel CooperAll In For Citrus Podcast, HLB Management

In the latest All In For Citrus podcast, Michael Rogers, director of the University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) Citrus Research and Education Center, discussed a statewide citrus workshop hosted at the Southwest Florida Research and Education Center in January. The event provided a day full of educational presentations covering a wide range of topics. Rogers …

workshop

Oxytetracycline Performance Addressed at Citrus Workshop

Daniel CooperEvents, HLB Management

The University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) hosted a statewide citrus grower workshop in mid-January at the Southwest Florida Research and Education Center in Immokalee. The event offered a full day of education covering a wide range of topics, including management of pests, diseases, weeds and nutrients. Ute Albrecht, UF/IFAS associate professor of plant physiology, provided …

grower

Grower Results With ReMedium TI® Mirror Researcher Results

Daniel CooperHLB Management, OTC Expert, Sponsored Content

Sponsored Content Question: Are there any updates on the performance of ReMedium TI® and citrus yield improvements? Answer: We are hearing from growers about groves in central and southern Florida where they are observing HLB recovery. I am getting reports from growers that have been steadfast users of ReMedium TI® that seem to be in agreement with much of the …

grove

Grove Conditions, Infrastructure and Funding Addressed

Daniel CooperProduction

In the recent Highlands County Citrus Growers Association (HCCGA) newsletter, Riley McKenna discussed conditions in groves, shrinking infrastructure and the importance of block grant funding. GROVE OBSERVATIONS McKenna, HCCGA president, stated that “faint hints of March bloom are already beginning to fill the air.” He added that the weather shows little indication of stabilizing or slowing tree growth, “which could …

brassinosteroids

Unraveling the Mechanisms Leading to Prolonged Tree Health by Combining IPCs and Brassinosteroids

Daniel CooperHLB Management, IPCs, Tip of the Week

By Fernando Alferez, Divya Aryal and Saoussen Ben Abdallah University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) research in the last three years has found that the combined use of individual protective covers (IPCs) and brassinosteroids (BRs) enhances protection of citrus trees against HLB and other diseases that limit citrus production in Florida. The research has been conducted …

quality

Brazil’s Orange Crop Forecast Drops Again

Tacy CalliesBrazil, Crop Forecast

Fundecitrus’ Dec. 10 orange crop forecast for the São Paulo and Triângulo/Southwest Minas Gerais Citrus Belt in Brazil is for 294.81 million boxes of oranges. That’s a reduction of 3.9% from the September forecast of 306.74 million boxes and a 6.3% reduction from the initial May forecast of 314.6 million boxes. The two main reasons for the reduction in the …

Florida

What We’ve Learned From 20 Years of HLB Research in Florida

Daniel CooperHLB Management, Research

By Michael Rogers It has now been two decades since huanglongbing (HLB), or citrus greening, was first detected in Florida. That announcement in August 2005 changed everything for the Florida citrus industry. At the time, Florida citrus was still a global powerhouse. Less than a year earlier, HLB had been confirmed in Brazil, and we were aware of its devastating …

trials

Trials Show Organic Tool Could Mitigate the Impact of HLB

Daniel CooperHLB Management, Organic

Mountain Valley MD Holdings Inc. (MVMD) recently reported positive results from ongoing citrus field trials in Brazil for its Agrarius™ signaling technology. Agrarius™ is designed to organically increase crop yields, reduce fertilizer and pesticide usage and enhance plant health. MVMD has been working with a client-directed third-party agricultural partner, FARM ATAC, in Brazil to assess the impact of the application …

updates

Florida Citrus Disease Updates

Daniel CooperDiseases

Plant pathologist Megan Dewdney on Nov. 20 presented updates on greasy spot, greasy-green, citrus black spot (CBS) and phytophthora brown rot. Dewdney is a University of Florida Institute of Food and Agricultural Sciences associate professor and Extension specialist at the Citrus Research and Education Center. GREASY SPOT AND GREASY-GREEN Dewdney reported that control measures for greasy spot, caused by the …

NVDMC

CITRUS NURSERY SOURCE: NVDMC’s Research Initiatives for 2025–26

Daniel CooperCitrus Nursery Source, Research

By Peter Chaires Last month’s Citrus Nursery Source article promised additional details on New Varieties Development & Management Corp.’s (NVDMC) 2025–26 sponsored projects. While there is only space for general summaries, it is important to highlight the areas of focus for each research team, and the emphasis on short-term benefits while continuing to build a foundation for the future. NVDMC …