Redbay ambrosia beetle-Laurel wilt complex: update and ...trec.ifas.ufl.edu/RAB-LW-2/pdfs/Current...

Current status and recommendations for control of laurel wilt and the

redbay ambrosia beetle

Jonathan H. Crane, Tropical Fruit Crop Specialist

UF/IFAS TREC, Homestead

Tropical Research and Education Center Homestead, Florida

Acknowledgments

• Dr. Jorge E. Peña, Entomologist, TREC • Dr. Randy C. Ploetz, Plant Pathologist, TREC • Dr. Edward Evans, Agri. Economist, TREC • Dr. Daniel Carrillo, Entomologist, TREC • Mr. Richard Gaskalla, Dir., DPI • Mr. Charles LaPradd, Ag. Mng., MDC • Mr. Alan Flinn, Adm., FL Avo. Comm. • Mr. Don Pybas, LW Coord., FL Avo. Comm.


Acknowledgments

Photograph credits include: • Michael Thomas, FDACS • Albert Mayfield III, FDACS Division of Forestry • James Johnson, GA Forestry Commission • Jonathan Crane, UF-IFAS-TREC • Mike Ulyshen, USDA Forest Service • Stephen Fraedrich, USDA Forest Service • Ian Maguire, UF-IFAS-TREC • Don Pybas, Avocado Administrative Committee


Outline • Why is this important? • Review of the threat? • Current status of the threat. • What has and is being done? • Current status of the effort at control in

avocado groves in Homestead. • Recommendations for control. • Future research. • Questions?


Florida avocado industry • Susceptible to the beetle and the disease Florida’s avocado industry • 7,500 acres • Farm gate value, $14 million • Wholesale value, $30 million • Impact to regional economy, $54 million • 951 growers, 35 handlers • Potential adverse effect to regional economy –

lost sales, property damage, increased management costs, $356 million


Florida native tree hosts

Native host trees • Redbay • Swampbay • Silkbay • Sassafras • Northern spicebush • Lancewood • Pondberry • Pondspice • Camphor (not native)

Damage to • Mammal food

sources • Butterfly food

sources • Potential

ecological impacts

Introduction and spread Distribution of Counties with Laurel Wilt Disease by Year of Initial Detection

Spread through the natural and urban areas by beetle flight and by people moving wood infested with the redbay ambrosia beetle.

The Florida

situation

Insect vector and pathogen

Redbay ambrosia beetle (Xyloborus glabratus)

• Very small (~2 mm in length).

• The RAB carries spores of the laurel wilt pathogen.

• Bores into the wood just below the bark and forms galleries in the sapwood.

Laurel wilt pathogen (Raffaelea lauricola)

• Grows and reproduces in xylem (water conducting tissue). – Blockage – Hypersensitive

reaction • The adult beetles and

their larvae feed on the fungus.

Pest complex

Redbay ambrosia beetle Laurel wilt pathogen

The damage to avocado trees


- Red pegs – LW positive; yellow pegs – LW suspects - Image: Don Pybas, LW Coordinator, Florida Avocado Administrative Committee

Laurel wilt detections in the Miami-Dade production area

Mature avocado trees positive for laurel wilt

4/11/2013

Leaf symptoms for laurel wilt

4/11/2013

Sawdust and holes from ambrosia beetle boring

4/11/2013

Dark staining of sapwood and beetle holes

Miami-Dade County - what can happen if you don’t act

Time

Probable root transmission of LW

Grove Months elapsed from initial find

Number of tree infected

1 4 months ~29 trees

2 6 months ~95 trees

Ambrosia beetles

Beetle infested wood Beetles infest remaining wood • Stumps • Large diameter wood

Update on samples taken and LW positive avocado trees, Miami-Dade County

• To date – – 193 samples taken – 66 positive for LW, that’s ~ 34%

• However, >350 trees have been destroyed. – ~0.08% of the estimated 643,800 commercial

avocado trees • Most death attributed to root movement

of the pathogen among root-grated avocado trees

Avocado cultivars positive for LW Brevard/Martin Counties Homestead Brogdon (complex hybrid) Beta (GxWI) Nadir (GxWI) Choquette (GxWI) Booth 8 (GxWI) Nesbitt (GxWI) Day (GxWI) Brooks Late (GxWI) Pollock (WI) Hall (GxWI) Choquette (GxWI) Simmonds (WI) Jim Lappeck (GxWI) Donnie (WI) Tower 2 (WI) Lula (GxWI) Hardee(WI) Waldin (WI) Monroe (GxWI) Loretta (GxWI) Pollock (WI) Lula (GxWI) Russell (WI) Miguel (GxWI) Winter Mexican (GxM) Monroe (GxWI)

LW spread

• Redbay ambrosia beetle (RAB) infestation (flight)

• RAB infested wood products: – Firewood – Limbs and stumps of cut trees

• Suspected - through root grafting among adjacent avocado trees

What has been/is being

done?


Organizing the effort - Florida Department of Agriculture and Consumer

Services-Division of Plant Industry (FDACS-DPI) Laurel Wilt Working Group

Purpose of Working Group • To assemble

• research, • regulatory and • industry

• There are 3 subgroups – Research – Regulatory – Outreach


Research Organizations involved • University of Florida, IFAS • USDA-Agricultural Research

Service • USDA-APHIS • US Forest Service • FDACS, Div. of Forestry • FDACS, Div. of Plant Industry • Iowa State University • University of Minnesota • University of California • Florida International University

Areas of research • Insect and disease

identification and control – Entomology – Plant Pathology – Germplasm preservation – Economics – Horticultural practices – Genetics – Detection technology

Regulatory lead agency FDACS-Division of Plant Industry

• Helping to organize and fund research, regulatory, and extension/outreach efforts. – Applied research/work-plan funding.

• Regulations on the movement of host plant material, e.g., firewood, and access procedures for destruction of infested/ infected trees.

• Detection and surveys for the pest and disease of natural, urban, and agricultural areas.

• Interface with USDA-APHIS.

Extension/Outreach Sub-group UF/IFAS - FDACS/DPI

• DPI links:

www.fl-dpi.com http://www.freshfromflorida.com/pi/

s a v e t h e g u a c . c o m • UF/IFAS Extension offices:

http://solutionsforyourlife.ufl.edu/map/index.html UF/IFAS publications: http://edis.ifas.ufl.edu UF/IFAS Tropical Research and Education Center: http://trec.ifas.ufl.edu

• USDA Forest Service:

http://www.fs.fed.us/r8/foresthealth/laurelwilt/

• The Nature Conservancy http://dontmovefirewood.org (Trees, Pests and People)

FDACS/DPI Helpline, 888-397-1517

What we’ve learned

through research


Acknowledgments University of Florida, IFAS • Dr. Jorge E. Peña, Tropical Fruits -

Entomologist • Dr. Randy C. Ploetz, Plant Pathologist –

Tropical Fruits • Dr. Edward A. Evans, Agricultural

Economist • Dr. Jonathan H. Crane, Tropical Fruit Crop

Specialist • Dr. Aaron J. Palmateer, Plant Pathologist –

Diagnostic Clinic • Dr. Jason A. Smith, Forest Pathologist • Dr. Lukasz L. Stelinski, Citrus Entomologist • Dr. Reza Ehsani, Agric.+Biol. Engineering Florida International University • Dr. Kenneth G. Furton, Chem./Biochem.

USDA-ARS • Dr. Paul E. Kendra, Entomologist • Dr. Nancy D. Epsky, Entomologist • Dr. Osman Gutierrez, Geneticist • Dr. David Kuhn, Molecular Biologist • Dr. Jerome Niogret, Entomologist • Dr. Tomas Ayala-Silva, Horticulturist FDACS-Division of Plant Industry – • Richard Gaskalla, Director • Denise Feiber, Public Inform. Florida Avocado Administrative Committee • Alan Flinn, Administrator Miami-Dade County • Charles LaPradd, Agric. Manager

Current research results on RAB • RAB is attracted to healthy trees. • RAB is much more attracted to native trees than

avocado (silkbay>redbay=swampbay>>>avocado>lancewood). • Most dispersing RAB beetles re-infest the same

tree or a trees close by. • Time from RAB infestation to emergence is 50 or

more days. • RAB flight is generally from 4PM-8PM and within

10 ft of the ground. • Damage or pruned avocado wood is more

attractive to RAB than non-damage/pruned wood.

Current research results on RAB and other ambrosia beetles

Other ambrosia beetles • LW spores have been detected on some

other species of ambrosia beetles. – Very low numbers

• Stressed trees (e.g., lightning, flood, root rot, etc.) are more attractive to these other ambrosia beetles than healthy trees.

• The number of RAB to emerge from avocado is minute compared to native host trees (i.e., avocado is not a good RAB reproductive host).

Current research results on RAB

• RAB attacks larger trees preferentially over smaller trees.

• Pruned/damaged avocado trees are more attractive to RAB than non-pruned/ damaged trees.

• Chipping RAB infested wood dramatically decreases RAB survival.

• In native area once the host tree population has been decimated the RAB populations decline greatly.

Current research results on LW • The molecular identification methodology for

LW has improved. • Larger trees are more affected by LW than

smaller trees. • Visual symptoms of LW lag behind internal

damage to the xylem conducting tissues. • LW does not survive in mulched wood chips. • LW is not transmitted by high-speed mechanical

pruning equipment (contrast, hand saws). • LW appears capable of moving to adjacent

avocado trees via root grafting. • LW has not quickly destroyed the avocado trees

in Brevard and Martin Counties during the past 5-7 years.

On-going research Plant Pathology • Biology of LW

– Host-pathogen interactions

– Physiology of avocado reaction

– LW Epidemiology • Diagnostics/detection • Transmission • Host resistance • LW avocado cultivar

evaluations • Fungicide efficacy

– Materials – Application methods

Entomology • Biology of RAB

– Life cycle – Flight behavior and

host attraction • Insecticide efficacy

– Materials – Application methods

• Repellents • Detection/monitoring • Attractants (trap/kill) • Biological control

– Beetle pathogens – Predators/parasites

• Barriers

On-going research Horticulture/Genetics • Cultural management • Integration into

sustainable avocado production scheme

• Tree health – nutrient and water management

• Genetics – breeding

Economics • Economic impact

analysis • Cost of mitigation

and control analysis

Chemistry/Engineering • Biochemical detection • Spectral detection

Redbay ambrosia beetle

Contact insecticide summary

Contact insecticides and adjuvants tested

Trade Name Active Ingredient Acelepryn Chlorantraniliprole (18.4%) Actara/Flagship 25WG Thiamethoxam (25%) Bifenthrin (25.1%) Brigade 2EC Pyrethroid/Bifenthrin (25.1%) Chlorpyrifos (40.2%) Cyazypyr/Exirel Cyantraniliprole Danitol 2.4 EC Pyrethroid/Fenpropathrin (30.9%) Endigo ZC Lambda-cyhalothrin + Thiamethoxam (2%)

Hero EW Pyrethroid/Zeta-cypermethrin (3.75%) + Bifenthrin (11.25%)

Kryocide Cryolite Na (96%) Lannate LV Carbamate/Methomyl (99.3%) Lorsban 4E Organophosphate/Chlorpyrifos (44.9%)

Contact insecticides and adjuvants tested

Results of Actara (thiamethoxam) testing

Therefore not recommended as a contact insecticide

Results of Malthion plus Vapor Gard and Pentrabark

Contact insecticide recommendations

Four contact insecticides worked • Recommended (mix with Vapor

Gard or Pentrabark) – Malathion – Danitol

• To be registered and recommended – Hero – Endigo

Laurel wilt pathogen

Ongoing work with fungicides

Laurel wilt pathogen control

• Application methods tested or under testing – Infusion – Injection – Soil drench – Bark directed

• Cost estimates calculated

Fungicides evaluated for activity against Raffaelea lauricola

Trade namey Active ingredient Chemical group

Daconil Ultrex chlorothalonil chloronitrile

Funginex triforine piperazine

Eagle 20EW myclobutanil triazole

Alamo propiconazole triazole

Prophesy 0.72G propiconazole triazole

Tilt propiconazole triazole

Proline 480SC prothioconazole triazole

Baytan 30 triadimenol triazole

Bayleton FLO triadimefon triazole

BAS 595 triticonazole triazole

Manzate 200F mancozeb dithiocarbamate

Terramaster 4EC etridiazole 1,2,4-thiadiazole

Arbotect 20S thiabendazole benzimidazole

Ridomil 2EC metalaxyl acylalanine

Agri-Fos phosphorus acid salt

Omega 500F fluazinam 2,6-dinitro-aniline

Heritage azoxystrobin methoxy-acrylate

Insignia WG pyraclostrobin methoxy-carbamate

Disarm fluoxastrobin dihyrdo-dioxazine

Compass 50WG trifloxystrobin oximino acetate

Emerald 70 WG boscalid pyridine-carboxamide

Prostar 70WP flutolanil phenyl-benzamide

Thirty fungicides have been tested for their potential use in controlling the laurel wilt pathogen

Fungicide infusion trial in Brevard and Martin Counties

The team • Dr. Jonathan Crane, Tropical Fruit Crop

Specialist, UF/IFAS • Dr. Randy Ploetz, Plant Pathologist, UF/IFAS • Mr. Tom Prosser, Rainbow Tree Care, MN • Mr. Greg Krogstad, Rainbow Tree Care, MN • Dr. Aaron Palmateer, Plant Pathologist, UF/IFAS • Mr. Tom White, Sr. Biologist, UF/IFAS • Mr. Josh Konkol, Lab. Technician, UF/IFAS • Mr. Ronney Wideman, Lab. Technician, UF/IFAS • Ms. Jill Ploetz, Lab. Technician, UF/IFAS

Fungicide infusion trial in Brevard and Martin Counties

2011 2012 J A S O N D J F M A M J J

Evaluated/sampled June 9, 2012

Infused July 14, 2011 Inoculated Oct., 14, 2011

Evaluated/sampled Dec., 13, 2011

60 days 239 days

2012 2013 J A S O N D J F M A M J J

~555 days

Current evaluation/sampling

Materials and methods

• During spring of 2011 mature avocado trees in Martin and Brevard Counties were evaluated for use in a LW fungicide trial.

• Sixty useable trees were identified from 10 avocado growers (1 in Martin Co., 9 and Brevard County).

• Trees infused with 1 of three fungicides tested on 11 or 12 July 2011.

• Trees inoculated with LW pathogen (Raffaelea lauricola) on 13 or 14 October 2011.

• Trees visually rated for symptoms and sampled for LW.

Treatment

Common name

Rate

Actual ratesz

ml oz Propiconazole Propiconazole Pro

14.3% Low 20 0.7

Med 30 1.0

High 40 1.4

Tebuconazole Tebuconazole 16% Low 20 0.7

Med 30 1.0

High 40 1.4

Thiabendazole Arbotect 20-S 26.6% Low ~30 1.0

Med ~60 2.0

High ~89 3.0

Control ---- ---- ---- ---

z, Rates are per inch tree diameter

Infusion trial in Brevard and Martin Counties

Treatment

Rate

Percentage of trees with some LW symptoms after

inoculation with LW* 2 months 8 months

Control ---- 86 100

Propiconazole Low 0 83

Med 0 100

High 0 67

Tebuconazole Low 33 84

Med 0 84

High 17 100

Thiabendazole Low 60 80

Med 50 100

High 67 100

Infusion trial in Brevard and Martin Counties *Dead leaves *Dead stems *Wilting

Percent LW positive trees after inoculation with LW Treatment Rate

2 months 8 months

Control ---- 57 100

Propiconazole Low 0 0

Med 0 17

High 0 17

Tebuconazole Low 33 50

Med 0 0

High 17 17

Thiabendazole Low 40 60

Med 33 67

High 67 83

Infusion trial in Brevard and Martin Counties

So how can trees look like LW but don’t?

• Some avocado trees had some small to moderate areas of their canopy with dead leaves, i.e., they looked like they had the beginnings of LW but were either not tested or when tested were found not to have the LW pathogen.

• Maybe: – Cold damage – Root rot – Salinity stress – Drought stress – Lightning stress

• More data collection during late April 2013.

Results

• Based on the findings from this investigation in Martin and Brevard (Merritt Island) Counties – Little to no phytotoxicity was consistently

related to any of the fungicides tested. – Propiconazole at the medium and high

rate protected trees from LW better than Tebuconazole and Thiabendazole at the rates tested.

– Work is now underway to permanently register propiconazole for use on avocado.

Current experimental testing to control LW

• The strategy – Identify LW infected trees as soon as possible – Remove LW infected tree completely (roots and all) and

destroy wood – Treat adjacent trees systemically with propiconazole (Tilt® ,

~$98-$132/gallon; Sect. 18) • In general, so far looks like some success in protecting adjacent

trees with this strategy but… • Issues that need to be addressed before this can be

recommended – Early enough detection of LW infected trees – Need equipment – Need training – The cost of treatment

• Leaving stumps - potential for continued disease spread through the root system

• LW infected trees have not been cured • NOT RECOMMENDED at this time • Further investigations to commence ASAP

Current RAB-LW detection and control

strategy

RAB-LW control Industry-wide early detection and

suppression of laurel wilt

Constantly control (suppress) the RAB population in the commercial agricultural area.

The commercial avocado production area is concentrated to the southeastern area of Miami-Dade County.

• Over time the number of urban and natural area native trees will decline – so may the RAB population – providing a buffer adjacent to the agricultural area.

• In the production area – keep the RAB population to a minimum by scouting and control (suppression).

• Once the native tree populations are dramatically reduced the RAB population and LW may be more manageable in the production area. – Dead trees do not make more RAB

Over time (2-4 years) potentially • Native hosts eliminated • Some loss of urban avocado • Expanding non-host zone • Decreased potential for RAB-LW

Expanding non-host zone over time

RAB-LW control strategy • Detect infestations as quickly as possible

– Provides an opportunity for RAB-LW suppression

• Ground scouting groves as frequently as possible

• Aerial survey of agricultural area (grid) – Locate, ground truth, sample, control

• Non-positive LW groves – Sampling suspicious trees for LW – Verification of cause of decline in LW-free groves

• In LW positive groves take immediate control action to prevent the spread of the disease

Avocado production area and RAB-LW aerial survey area quadrants

1 2

3 4

Current process • Aerial helicopter

survey with GPS unit • Provide Google Earth

aerial maps and GPS coordinates of suspect groves (trees) to industry

• Industry ground truths grove sites – Sample if

warranted – Control action if

warranted

• Helicopter Partners, Inc. – Tamiami Airport

• Equipment – Garmin GPS unit

• Flight – 100-300 ft – Grid-like pattern, E-W – Groves/trees of

interest marked with GPS unit

Avocado aerial survey for LW and RAB 2011

Blue line = helicopter path

Northwest quadrant example

Northwest quadrant example showing street location

Avocado – general view from air

Avocado LW suspect - note distance

Broken branches not suspects

Difficult to differentiate • Phytophthora root rot • Flood stress • Freeze stress • Lightning

New detection projects • Aerial spectral analysis • Canine detection

New/old issues 1. Non-RAB ambrosia beetles

a. May transmit LW (no LW spores recovered from other beetle species infesting avocado)

b. Are attracted to stressed trees (e.g., lightning, Phytophthora, etc.)

2. In LW positive groves (sites) a. Killing ambrosia beetles inside trees and wood b. Killing ambrosia beetles trying to bore into trees

and wood c. Killing ambrosia beetles in the LW positive area

3. Root transmission of LW among avocado trees

4. Rapid identification of LW positive trees

• Refining recommendations to address these issues

Put another way • How do you prevent RAB from

spreading LW in and among groves? • How do you prevent RAB from

becoming established in the avocado production area?

• Once the LW pathogen is in a grove – How do you prevent infection of

adjacent trees? – How do you prevent the disease from

spreading by root grafts among trees?

Insect suppression

• Early detection/suppression of RAB, over time – Loss of native host trees and reduced

potential for RAB reproduction • Provides an opportunity to

– Suppress RAB populations by completely destroying RAB-LW infected avocado wood and trees

– To reduce potential transmission of LW by other ambrosia beetles

Recommendation-1

To reduce potential LW transmission by other ambrosia beetles • Improve and maintain health of trees in

the groves – Maintain or improve cultural management

to prevent water and nutrient stress – Remove environmentally stressed (e.g.,

lightning) trees immediately • These trees attract ambrosia beetles

– Remove chronically diseased trees (e.g., Phytophthora root rot)

• These trees attract ambrosia beetles

Recommendation-2 for laurel wilt positive avocado trees

• Remove LW positive trees promptly and completely – The earlier LW symptoms are detected the

greater the chances to reduce LW spread among adjacent trees

– Push or pull trees from ground – Chip all wood possible, spread chips out and

spray with insecticide (Malathion or Danitol) plus adjuvant (Vapor Gard or Pentrabark)

• Beetles attracted to chips • Do not leave chips in piles

– Burn large diameter wood, stumps and trunks (and possibly chips)

• Usually takes more than one burning event

RAB control

• Ambrosia beetles may be found – Inside an infested tree – On lower tree surfaces (trunks,

major limbs) – Flying in the air or on foliage and

branches


Recommendation-3 for RAB control in the grove

Inside the tree • Chipping and burning shown to be effective. • Systemic insecticides under investigation.

On lower tree surfaces (bark directed spray) • Spray adjacent avocado trees (trees in the

immediate area) from 10 ft down to ground with insecticide (e.g., Malathion or Danitol) plus adjuvant (Vapor Gard or Pentrabark). Thorough coverage of trunk and major limbs is critical.

Recommendation-3 for RAB control in the grove

On upper tree surfaces or flying in the grove • Make 1 or more aerial insecticide

applications – Immediate LW positive grove area – Late afternoon/early evening (4PM-8PM) – Malathion or Danitol – Use NuFilm adjuvant (don’t use Vapor

Gard or Pentrabark)

Recommendation-4: Intensify scouting of the grove to quickly identify any other symptomatic trees that may need to be removed.

So why comply with tree destruction?

• Infestation/infection spread to adjacent or nearby groves • Loss of production and potential income o Tree Destruct Compensation Program, Avocado Administrative Committee

Florida Avocado Administrative Committee – Tree Destruct Compensation Program

• Limited funds, just for LW tree destruction compensation

• Procedures for verification of LW – Testing trees the first time – Testing trees some distance away

• Proper disposal – Tree destruction completed properly – Use of an approved tree destruct

company

Current research and future – as new strategies are developed

RAB control • Repellents • Trap/kill • Predators/

parasites • Beetle

pathogens • Barriers • Reduced RAB

populations

LW control • Better detection of LW • Improved application

techniques • More effective

fungicides • Longer-lasting

fungicide materials • Identification of

tolerant cultivars

Thanks for your attention Questions?


Redbay ambrosia beetle-Laurel wilt complex: update and ...trec.ifas.ufl.edu/RAB-LW-2/pdfs/Current...

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