An established infection in the Florida Citrus Industry

May 2018

CITRUS CANKER1

CONTACTSUF/IFAS Citrus Research and Education Center

Jamie Burrow2

Extension Program Manager863-956-8648

Megan Dewdney, Ph.D.2

Plant Pathologist863-956-8651

Lukasz Stelinski, Ph.D.Entomologist863-956-8851

Evan Johnson, Ph.D. Plant Pathologist

863-956-8649

UF/IFAS Indian River Research and Education Center

Mark Ritenour, Ph.D. Postharvest Physiologist

772-468-3922

UF/IFAS Southwest Florida Research and Education CenterOzgur Batuman, Ph.D.

Plant Pathologist239-658-3408

UF/IFAS Extension Offices with Citrus AgentsHardee, Hendry, Highlands, Lake, Polk, St. Lucie, Sumter

WebsitesUF/IFAS Extension Citrus Agents

http://citrusagents.ifas.ufl.edu

UF/IFAS Citrus REC www.crec.ifas.ufl.edu

UF/IFAS Indian River REC http://www.irrec.ifas.ufl.edu

UF/IFAS Southwest Florida REC http://www.imok.ufl.edu

Local UF/IFAS Extension Office http://solutionsforyourlife.ufl.edu/map/

COMMERCIAL MANAGEMENT• Decontamination of equipment and personnel

• Windbreaks

• Copper sprays

• Stimulate natural defense in young trees

• Leafminer control

• Defoliation

• Tree removal

1. This document is CH199, one of a series of the Plant Pathology Department, UF/IFAS Extension. Original publication date, July 2008. Revised May 2018. Visit the EDIS website at http://edis.ifas.ufl.edu.

2. J. D. Burrow, Extension program manager; and M. M. Dewdney, associate professor, Plant Pathology Department, UF/IFAS Citrus Research and Education Center, Lake Alfred, FL 33850.

The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations. For more information on obtaining other UF/IFAS Extension publications, contact your county’s UF/IFAS Extension office.

U.S. Department of Agriculture, UF/IFAS Extension Service, University of Florida, IFAS, Florida A & M University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Nick T. Place, dean for UF/IFAS Extension.

CH199

RESIDENTIAL MANAGEMENT• Apply copper every three weeks mid-May to mid-July

• Decontaminate lawn tools using one (1) ounce of bleach to one (1) gallon of water. (Do not store bleach-water solution as it will lose effectiveness within 24 hours.)

• Prune infected area, double bag infected limbs, and discard in yard waste or

• Burn infected plant material

• Apply horticultural oil to lower leafminer populations

• Do not transport infected plant material!

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

CANKER HISTORY CANKER SYMPTOMS1910First introduction into Florida

1933Eradication of first introduction of canker was successful

1986Second introduction into Florida on the Gulf coast

1994Second introduction of canker was declared eradicated

1995Third introduction into Florida in urban Miami area

2000A statewide mandatory eradication using 1,900 foot rule was implemented

Quarantine areas were established when canker was detected

Mandatory statewide decontamination procedures began

2002Removal of infected and exposed trees was delayed due to lawsuits from homeowners

2004–2005The hurricanes magnified the spread of canker across the state

2005First nursery infected with canker was found

2006Mandatory eradication ended

2007 to presentLocated in the majority of Florida counties

The removal of infected trees is now voluntary

Decontamination procedures are required statewide in commercial groves to prevent the spread of citrus canker

Leaf Symptoms• Early symptoms appear as slightly raised, tiny

blister-like lesions

• As lesions age, they turn tan to brown and a water soaked margin appears surrounded by a yellow ring or halo

• Center of the lesion becomes raised and corky

• Lesions are usually visible on both sides of a leaf

VARIETIES AFFECTED• Highly susceptible varieties: grapefruit, lemons, navel,

some early oranges (ex. Early Gold)

• Less susceptible: Hamlins, tangelos

• More tolerant: tangerines, hybrids (ex. Murcott), Valencia

CANKER SPREAD• Wind-driven rain and storm events such as tornadoes

and tropical storms

• Overhead irrigation

• Human movement of infected plant material

• Human and equipment movement within groves

• Citrus leafminer

• Birds and other animals

• Canker does not harm humans

Citrus canker is highly infectious!

BIOLOGY• Bacteria is caused by Xanthomonas citri subsp. citri

• Gram negative bacterium

• Small (cannot be seen by the naked eye)

• 1–3 microns in size

• Rod-shaped cell covered with slime

• Single polar flagellum

• Survives in moist conditions

Stem and Fruit Symptoms• Older stem lesions are dark brown or black, raised,

corky lesions surrounded by an oily or water-soaked margin

• Mature lesions appear scabby or corky

• Fruit lesions are dark brown to black, raised, often surrounded by yellow halos

• Fruit lesions can cause blemishes and early fruit drop