Build Resilience in HLB-Affected Hamlin Trees

Jim Rogers HLB 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

Jim Rogers HLB 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

Jim Rogers HLB 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

Jim Rogers Research

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 Neff Research, 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 Neff Varieties

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 Callies Research, 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 Neff Varieties

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. …

Optimize Zinc and Potassium Applications to Prevent Fruit Drop

Jim Rogers Fruit Drop, Nutrition, Tip of the Week

By Fernando Alferez, Daniel Boakye, Murillo De Sousa and Pablo Orozco After HLB was first detected in Florida, increase in disease-associated preharvest fruit drop in affected trees has significantly reduced grower returns. Fruit drop is normal in healthy citrus, accounting for 10% to 15% of the total crop. However, under endemic HLB conditions and depending on the variety, crop loss …

Combine Plant Growth Regulators for Most Benefit

Jim Rogers Citrus Expo, PGRs

Using the plant growth regulators (PGRs) gibberellic acid (GA), 2,4-D and cytokinin in combination can maximize the benefit for HLB-affected trees, researcher Tripti Vashisth reported recently. The University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) associate professor of citrus horticulture and production works at the Citrus Research and Education Center in Lake Alfred. She discussed the benefits of …

Treat HLB Trees With the Right PGR at the Right Time

Jim Rogers HLB Management, PGRs, Research

By Tripti Vashisth, Wesley Webb and Taylor Livingston As trees become symptomatic for HLB, leaves experience an imbalance of plant hormones. This hormonal imbalance exacerbates HLB symptoms and can lead to more stem dieback, poor vegetative growth and fruit drop. This ultimately leads to reduced bearing wood, resulting in yield losses and tree decline. Thus, the use of growth-promoting hormones …

HLB Tools for Today and Tomorrow

Jim Rogers Citrus Expo, HLB Management

By Frank Giles and Tacy Callies The Citrus & Specialty Crop Expo hosted two citrus educational sessions during the Aug. 16–17 event held at the Florida State Fairgrounds in Tampa. The sessions included both long-term research aimed at delivering trees resistant to HLB as well as what growers can do today to help mitigate the effects of the disease in …

Season’s First Update to Brazil’s Orange Forecast

Jim Rogers Brazil, Crop Forecast

The first update of the 2023–24 orange crop forecast for the São Paulo and West-Southwest Minas Gerais citrus belt confirmed the initial May forecast of 309.34 million boxes. Fundecitrus announced the update on Sept. 11. The forecast for Hamlin, Westin and Rubi varieties was increased 3.5% to 58.09 million boxes. Other early-season varieties climbed 1.6% to 18.51 million boxes. The …

Accelerating Citrus Breeding Efforts

Jim Rogers Breeding

By John M. Chater Professors Jude Grosser and Fred Gmitter have been breeding improved citrus varieties at the University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) Citrus Research and Education Center (CREC) for decades. Over time, they have released several of their advanced selections. Many of these selections are sweet oranges. There is a subset of these creations …

Citrus Breeding Efforts to Solve the Brix Crisis

Jim Rogers 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

Jim Rogers 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 …

Update on the Cold-Hardy Citrus Region

Jim Rogers Cold Hardy

By Danielle Sprague Williams In North Florida and South Georgia, there has been a significant growth in citrus production due to the relatively mild winters, advances in freeze protection and cold-hardy citrus varieties. In addition to this, there is a relatively low incidence of the citrus greening pathogen and its vector, the Asian citrus psyllid. Due to these factors, many …

Sustaining Citrus With Soil Improvement

Jim Rogers Cover Crops, HLB Management, Soil Health

By Frank Giles HLB has taken a toll on growers both large and small over the years. That’s been the case with third-generation grower Chuck Bellamy, who grows citrus near Inverness, Florida. His grandparents planted the first trees on the property in 1930. A few of those trees are still alive in the grove nearly 100 years later. Bellamy says …

Valencia on US-942 Rootstock Is Favored Florida Tree

Jim Rogers 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 …

Brazil’s Initial Orange Forecast for 2023–24

Tacy Callies Brazil, Crop Forecast

The 2023–2024 initial orange forecast for Brazil’s citrus belt is 309.34 million boxes. The forecast was announced on May 10 by Fundecitrus and its cooperators. The projected volume is 1.55% less than the previous crop, which totaled 314.21 million boxes. Fundecitrus reported that weather conditions are positive for the 2023–24 crop with rains being 50% above the historical average. However, …