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Scouting for Huanglongbing (HLB; Citrus Greening)1

Jamie D. Burrow, Stephen H. Futch, Tripti Vashisth, and Timothy M. Spann 2

This illustrated trifold brochure is best viewed in pdf format. It highlights the purpose of scouting, frequency, methods, grove conditions, tagging suspect trees, scout responsibilities, safety concerns, diagnostics, and what to scout for. Includes contact information for UF/IFAS Extension citrus experts.

Click here to download this brochure.

Purpose of Scouting

The purpose of scouting is to aid in managing HLB by:

  • Identifying HLB-affected trees

  • Planning a management program

When to Scout

  • Symptoms are most visible during the fall and winter months

  • Survey frequency would be determined by incidence and HLB management plan

  • Spring flush makes scouting more difficult


  • Walking

  • ATVs

  • Tractor- or vehicle-mounted platform

Scout Responsibilities

  • To locate and identify HLB symptoms

  • Operators of platforms and ATVs are responsible for transporting survey crews safely

  • Follow all company procedures for entering and exiting grove

Tagging Suspect Trees

  • Use one color of flagging tape to identify suspect trees

  • Choose colors or designs that cannot be confused with other commonly used flagging tapes

  • GPS or grove map should be used in conjunction with flagging tape to identify positive HLB-affected tree

Grove Conditions

Grove conditions which can hinder a scouting program include:

  • Unmaintained grove middles, tree size, and/or canopy

  • Nutrient deficiencies

  • Non-hedged rows

  • Disease or insect damage

Safety Concerns

  • Safety is a priority when scouting

  • Follow re-entry intervals for chemical applications

  • Be aware of weather, climate conditions, and grove conditions

  • Watch for power lines

  • Always keep a first aid kit in a readily accessible location

  • Employees should be trained in the proper procedures in case of an emergency

What to Scout For


Yellow veins, vein corking, and green islands are not diagnostic alone. These symptoms should be coupled with blotchy mottle symptoms and a positive diagnostic test to determine a diagnostic test tree.

Figure 14. Trees with a yellow appearance, shoot dieback, sparse foliation, and thin canopy.
Figure 14.  Trees with a yellow appearance, shoot dieback, sparse foliation, and thin canopy.

Figure 15. Blotchy mottle leaves.
Figure 15.  Blotchy mottle leaves.

Figure 16. Vein corking and blotchy mottle.
Figure 16.  Vein corking and blotchy mottle.

Figure 17. Green islands.
Figure 17.  Green islands.

Figure 18. Lopsided, misshapen, small fruit.
Figure 18.  Lopsided, misshapen, small fruit.

Figure 19. Yellow veins and/or off-season bloom.
Figure 19.  Yellow veins and/or off-season bloom.

Diagnostic Labs

Southern Gardens Diagnostic Laboratory
111 Ponce de Leon Ave.
Clewiston, FL 33440
(863) 902-2249
Contact: Mike Irey
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.


UF/IFAS Citrus Research and Education Center
Jamie Burrow
Canker & Greening Extension Education
(863) 956-8648
Megan Dewdney, Ph.D.
Plant Pathologist
(863) 956-8651
Tripti Vashisth, Ph.D.
(863) 956-8846
Lauren Diepenbrock, Ph.D.
(863) 956-8801
UF/IFAS Southwest Florida Research and Education Center
Ozgur Batuman
Plant Pathologist
(239) 658-3408
Jawwad Qureshi, Ph.D.
(772) 577-7339
UF/IFAS Indian River Research and Education Center
Liliana Cano, Ph.D.
Plant Pathologist
(772) 577-7350
UF/IFAS Extension Offices with Citrus Agents
DeSoto, Hardee, Hendry, Highlands, Lake, Polk, St. Lucie, Sumter
UF/IFAS Extension Citrus Agents
UF/IFAS Southwest Florida REC
Local UF/IFAS Extension Office

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


1. This document is CH201, one of a series of the Horticultural Sciences Department, UF/IFAS Extension. Original publication date August 2008. Revised December 2019. Visit the EDIS website at
2. Jamie D. Burrow, Extension program manager; Stephen H. Futch, Extension agent IV (retired); Tripti Vashisth, assistant professor, Horticultural Sciences Department, UF/IFAS Citrus Research and Education Center; and Timothy M. Spann, former associate professor, Horticultural Sciences Department, UF/IFAS CREC; UF/IFAS Extension, Gainesville, FL 32611.

Publication #CH201

Date: 12/9/2019

Related Experts

Vashisth, Tripti

University of Florida

Spann, Timothy M

University of Florida

Futch, Stephen H.

University of Florida

Burrow, Jamie D.

University of Florida

    Fact Sheet


    • Jamie Burrow
    • Tripti Vashisth