Huanglongbing History

• In 1995, the official name for greening became Huanglongbing (HLB)

• The vector, Asian citrus psyllid, was first found in Florida in 1998

• HLB was first detected in residential areas in South Florida in August 2005

• As of October 2006, HLB affected trees had been found in twelve counties

• By October 2007, affected trees had been discovered in twenty-eight counties

• Thirty-two counties had confirmed greening in their area by the end of 2008

• By February 2010, thirty-four counties had at least one positive confirmed HLB affected tree

• HLB is now confirmed in all commercial citrus growing counties in Florida

• Currently, identified in most non-commercial citrus growing counties in residential properties

Huanglongbing Biology

• A disease caused by a phloem-limited bacterium affecting all citrus cultivars

• The rod-shaped, Gram-negative bacterium is named Candidatus Liberibacter asiaticus

• Bacterium does not move between trees without the insect vector or through grafting

• The bacteria are present in symptomatic tissues in low numbers

• Phloem tissue is damaged when bacteria are present

• Starch accumulates to toxic levels in plant cellsExcessive phloem tissue is produced in infected trees

• Bacteria are at their highest levels in young asymptomatic tissues and appear to die as tissues age and become symptomatic

• Changes to the plant tissue begin in the early infection before symptoms

Varieties Affected

• All citrus varieties and rootstocks can be affected by HLB

• Affects plants in the Rutaceae family (ex. box orange and orange jasmine)

Greening Vector

• Asian citrus psyllid (Diaphorina citri)

• Five nymphal stages

• Numerous generations per year

• Egg to adult in 2 weeks at 75°F to 85°F

• Egg stage lasts an average of 3 to 4 days

• Duration of the nymphal stages is about 12 to 14 days at 82°F

• Adult psyllids may live for several months in cool temperatures

• Psyllids can acquire the bacterium from infected trees, regardless of whether symptoms are present on the tree

• The longer psyllids remain uncontrolled and are allowed to feed on infected trees, the higher the chance that those psyllids will acquire and spread HLB to other trees

• Psyllid populations are best managed by controlling adults prior to the presence of new flush which facilitates rapid population growth

• Chemical control of the psyllid and removal of infected trees are the only methods currently available to manage the spread of greening

Commercial Management

• For detailed information, please see UF/IFAS Guidance for Huanglongbing (Greening) Management (https://edis.ifas.ufl.edu/hs1165)

• Citrus Health Management Areas (https://crec.ifas.ufl.edu/extension/chmas/)

Residential Management

• Remove infected trees

• Use of disease-free nursery trees (a certified nursery tag should be attached to tree at time of purchase)

• Use horticultural oil sprays to manage psyllid populations

• When applying pesticides, remember the label is the law

• The Florida Department of Agriculture has a release program for the Tamarixia radiata, a beneficial insect of the psyllid. For more information, visit https://www.freshfromflorida.com/

Greening Symptoms

• Symptoms can be found year round, but are more prominent September through March

Diagnostics

Southern Gardens Diagnostic Laboratory

111 Ponce de Leon Ave.

Clewiston, FL 33440

(863) 902-2249

Contact: Mike Irey

msirey@ussugar.com

Florida Division of Plant Industry

PO Box 147100

Gainesville, FL 32614-7100

(800) 282-5153

UF Plant Diagnostic Center

Building 1291, 2570 Hull Rd.

Gainesville, FL 32611

352-392-1795

Before sending samples, contact the testing facility to obtain proper sampling procedures, submission guidelines, and fees.

Contacts

UF/IFAS Citrus Research and Education Center

Jamie Burrow

Extension Program Manager

863-956-8648

Megan Dewdney, Ph.D.

Plant Pathologist

863-956-8651

Tripti Vashisth

Horticulturist

863-956-8846

Lauren Diepenbrock, Ph.D.

Entomologist

863-956-8801

UF/IFAS Indian River Research and Education Center

Rhuanito "Johnny" Ferrarezi, Ph.D., Horticulturist

772-577-7376

Liliana Cano, Ph.D., Plant Pathologist

772-577-7350

Jawwad Qureshi, Ph.D., Entomologist

772-577-7339

UF/IFAS Southwest Florida Research and Education Center

Ute Albrecht, Ph.D., Plant Physiologist

239-658-3422

Fernando Alferez, Ph.D., Horticulturist

239-658-3426

Ozgur Batuman, Ph.D., Plant Pathologist

239-658-3408

Phil Stansly, Ph.D., Entomologist

239-658-3427

UF/IFAS Extension Offices with Citrus Agents

Hardee, Hendry, Highlands, Lake, Polk, St. Lucie, Sumter

Websites

UF/IFAS Extension Citrus Agents

http://citrusagents.ifas.ufl.edu

UF/IFAS Citrus REC

http://www.crec.ifas.ufl.edu

UF/IFAS Southwest Florida REC

https://swfrec.ifas.ufl.edu/

Local UF/IFAS Extension Office

http://sfyl.ifas.ufl.edu/find-your-local-office/

For more information, please contact the UF/IFAS Citrus Research and Education Center, Lake Alfred 863-956-1151