- Author: Ben Faber
- Author: Ben Faber
Huanglongbing Update
As of November 5, a total of 2,619 trees and 368 ACP have tested positive via PCR for the bacterium that causes HLB. The most recent activity has been in Orange and San Bernardino counties. Infected trees have been or are being removed, additional HLB detection surveys and ACP treatments are applied on a recurring basis to remaining citrus in those areas.
For additional details, please see the updated HLB quarantine and treatment map and table at maps.cdfa.ca.gov/WeeklyACPMaps/HLBWeb/HLB_Treatments.pdf.
For information on regulatory and treatment requirements growers can expect should HLB be detected in or near your citrus grove or packing house, please refer to CDFA's Information for Citrus Growers/Grove Managers, Action Plan for ACP and HLB or this summary flyer.
Regulatory Update
Mustang Maxx has been approved for Spray and Harvest. For growers who harvest in one ACP Regional Quarantine Zone and pack in another, and use Spray and Harvest as their mitigation for moving bulk citrus, the list of approved ACP materials has been updated. The most recent list and protocols for quarantine compliance can always be found in the Information for Growers/Grove Managers document from CDFA. Please keep in mind this is separate and distinct from protocols and materials for Area Wide Management, discussed above.
Additional ACP/HLB Resources
- Check out the new and improved CDFA Citrus Division website: https://www.cdfa.ca.gov/Citrus/
- General ACP/HLB
oInformation on the state ACP/HLB program including maps, quarantine information, and a signup option for email alerts: citrusinsider.org/
oBiology of ACP and HLB, detection maps and recommendations for monitoring, eradication and management: ucanr.edu/sites/acp/
oUC IPM recommendations for ACP
oWeb-based map to find out how close you are to HLB: ucanr.edu/hlbgrowerapp
oVideo on Best Practices in the Field, available in English and Spanish
- Research
oUC Ag Experts Talk presentations on management of various citrus pests and diseases are available for viewing here and here on YouTube.
oSummaries of the latest research to combat HLB: ucanr.edu/sites/scienceforcitrushealth/
oScience-based analyses to guide policy decisions, logistics, and operations: www.datoc.us
- Regulatory/Quarantine
oSign up for program updates from the Citrus Pest and Disease Prevention Division at www.cdfa/signup-email-updates.
oRegulatory requirements for moving bulk citrus: Information for Citrus Growers
oSummary of regulatory requirements in the event of an HLB detection in commercial citrus: citrusinsider.org/Regulatory-Flyer
by koestoyo
University of Florida researchers publish award-winning findings on orange grove design to produce fruit under HLB
FORT PIERCE, Fla.— The American Society for Horticultural Science will honor University of Florida scientists for new guidelines citrus growers may apply to their operations. The researchers study ‘Valencia' orange production while trees are under the most serious citrus disease worldwide.
“The 7-year study broke new ground on data we provide to local citrus growers who remain in business despite huanglongbing, or HLB,” said Ronald D. Cave, Director of the University of Florida Institute of Food and Agricultural Science's Indian River Research and Education Center in Fort Pierce (UF/IFAS-IRREC).
A few of the findings citrus growers may employ immediately from the study are:
• High-density plantings produce more fruit—from 86% up to 300% more than trees not planted in high-density configurations under HLB.
• The study showed that advanced management practices that included high tree density, fertigation, and drip irrigation led to higher fruit yield.
• Additional research is needed to determine optimal fertilization rates for high-density sweet orange orchards under HLB-endemic conditions
The award-winning publication, “Sweet Orange Orchard Architecture Design, Fertilizer, and Irrigation Management Strategies under Huanglongbing-endemic Conditions in the Indian River Citrus District,” appears in the December 2020 issue science of the scientific journal HortScience. The paper describes the scientists' hypothesis, the entire research procedure, outcomes, and recommendations for further research.
Members of the American Society for Horticultural Science (ASHS) Fruit Publication Selection Committee wrote about the paper's significance. “Huanglongbing, also known as citrus greening, affects all citrus cultivars and causes serious tree decline. It is currently a major threat to the citrus industry. The results can influence the whole citrus industry to deal with HLB including orchard architecture design, fertilizer, and irrigation management strategies.”
Rhuanito “Johnny” Ferrarezi and his colleagues conducted experiments to determine the variables that promote healthy fresh fruit harvests with the presence of HLB. Ferrarezi, along with fellow professors Mark Ritenour and Alan Wright, will accept the “Outstanding Fruit Publication Award” for papers published in 2020 at the ASHS annual meeting awards ceremony in Denver, Colorado, Aug. 6. Ferrarezi is an Assistant Professor of Citrus Horticulture; Ritenour, Professor of Postharvest Technology; Wright, Professor of Soil and Water Science.
Others who contributed to the research and the award-winning publication are Arun D. Jani, a post-doctoral research assistant; Thomas James III, who manages citrus research groves; and Cristina Gil, an agricultural research assistant.
“We strive to keep citrus growers in business even though HLB is reducing the profitability of infected trees over time,” said Ferrarezi. “The point is to sustain younger trees for a number of harvests to produce the healthy, delicious fruit that made the Indian River District famous.”
- Author: Ben Faber
|
- Author: Ashley Robinson
The Australian finger lime, a citrus relative, could be a new specialty crop for Florida citrus growers.
Traditionally, finger limes have remained rare in the United States, grown few and far between. However, the fruit's unique tolerance to HLB is becoming increasingly attractive to Florida growers. Manjul Dutt, research assistant scientist at the University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) believes finger limes could secure Florida's position in the global citrus market.
In the field, finger limes have a low HLB infection rate. Early on, researchers noticed these trees were much more tolerant to HLB than any of the traditional citrus varieties being grown in the state.
“We have a number of theories as to why this finger lime could be tolerant to HLB,” Dutt says. “It could be due to the presence of physical barriers, or it could be due to the presence of certain toxins or certain chemicals in the phloem that the Candidatus Liberibacter asiaticus' (CLas) doesn't like.” CLas is the bacterium that causes HLB.
The young flesh of finger limes contains high levels of anthocyanins, producing a dark-red color on the leaves of the tree. Studies have indicated that insects, including the Asian citrus psyllid, move according to visual cues. It's possible the high levels of anthocyanins can discourage psyllid feeding and thus prevent transmission of HLB.
Additionally, the phloem of the finger lime contains high levels of aldehyde compounds. According to Dutt, citronellol, a compound of growing interest and present in the phloem, has shown to have anti-bacterial activity, which could also be preventing the replication of CLas.
One of the pressing issues limiting commercial production of finger limes in Florida is the lack of knowledge about the crop. Dutt and his team of researchers are currently evaluating different rootstocks in hopes of finding varieties suitable for Florida's growing conditions.
Furthermore, they are developing new cultivars that are crosses between conventional citrus and finger limes to incorporate HLB tolerance into traditional citrus varieties. Dutt says thousands of trees are currently being evaluated and quite a few appear promising
Tapping into their genetics
While finger limes aren't exactly set out to be the new crop replacing Florida's longstanding orange and grapefruit industry, Dutt believes finger lime trees can provide a strong assist. “Hybrids between finger limes and sweet orange down the road may have sweet orange-like traits that can be acceptable to the grower and consumer. It would create a sweet orange-like fruit with finger lime genetics that allow it to be tolerant to HLB,” he says. “Many people in the industry realize it's a long-term process. Some are skeptical but overall, people are hopeful that the finger-lime genetics play an important role in providing HLB-tolerant trees in the future.”
To date, finger limes are more of a niche crop in North America with only a few growers in California, Hawaii and Florida.
In the meantime, Dutt has produced a finger lime hybrid that looks like a larger finger lime. “We'll be releasing it this summer—it's similar to the finger lime but it has more pulp and the same “pearls” that finger limes do,” he says. He adds that it's a commercial release as a niche crop and hopes the limes will be available in stores in the next three to four years
For more information:
Dr. Manjul Dutt
University of Florida
Tel: +1 (863) 956-8679
manjul@ufl.edu
https://crec.ifas.ufl.edu/