Laurel wilt: A destructive new disease in the southeastern US Randy Ploetz University of Florida Tropical Research & Education Center Homestead, FL
Chronology An exotic ambrosia beetle, Xyleborus glabratus, detected in Port Wentworth, 2002
Chronology An exotic ambrosia beetle, Xyleborus glabratus, detected in Port Wentworth, 2002 Shortly thereafter, dying red bay (Persea borbonia) trees noted in surrounding area Fraedrich et al. 2008
Chronology An exotic ambrosia beetle, Xyleborus glabratus, detected in Port Wentworth, 2002 Shortly thereafter, dying red bay (Persea borbonia) trees noted in surrounding area Confusion over cause becomes realization that a new disease is responsible Fraedrich et al. 2008
Chronology An exotic ambrosia beetle, Xyleborus glabratus, detected in Port Wentworth, 2002 Shortly thereafter, dying red bay (Persea borbonia) trees noted in surrounding area Confusion over cause becomes realization that a new disease is responsible A new fungus, Raffaellea lauricola, that is related to the Dutch elm disease pathogen causes laurel wilt in controlled studies
Chronology An exotic ambrosia beetle, Xyleborus glabratus, detected in Port Wentworth, 2002 Shortly thereafter, dying red bay (Persea borbonia) trees noted in surrounding area Confusion over cause becomes realization that a new disease is responsible A new fungus, Raffaellea sp., that is related to the Dutch elm disease pathogen causes laurel wilt in controlled studies X. glabratus is shown to vector the pathogen
Chronology An exotic ambrosia beetle, Xyleborus glabratus, detected in Port Wentworth, 2002 Shortly thereafter, dying red bay (Persea borbonia) trees noted in surrounding area Confusion over cause becomes realization that a new disease is responsible A new fungus, Raffaellea sp., that is related to the Dutch elm disease pathogen causes laurel wilt in controlled studies X. glabratus is shown to vector the pathogen Laurel wilt moves rapidly along the Eastern seaboard
Soultis et al. 2000
Piper nigrum, black pepper Magnolia grandiflora
The Laurels Chanderbali et al. 2001
The Laurels Some species are important sources of timber Chanderbali et al. 2001
The Laurels Ocotea porosa Ocotea rubra Ocotea ballata Chanderbali et al. 2001
The Laurels Some are important sources of spices and condiments Chanderbali et al. 2001
The Laurels Umbellaria californica Cinnamomum camphor Cinnamomum verum Laurus nobilis
The Laurels There is an important commercial fruit species in the family, Chanderbali et al. 2001
The Laurels Persea americana
The Laurels and they are ecosystem components in the continental US Chanderbali et al. 2001
The Laurels Nectandra coricea Sassafras albidum Persea borbonia
The Laurels and they are ecosystem components in the continental US, as well as tropical America Chanderbali et al. 2001
The Laurels
The Laurels Sassafras albidum Early in the laurel wilt epidemic, the susceptibility of four species native to the SE US was reported Lindera melissifolia, pondspice Litsea aestivalis, pondspice Persea borbonia, red bay
The Laurels Sassafras albidum Lindera benzoin, northern spicebush *Persea americana and by 2006, another native and a non-native species were added to the host list Lindera melissifolia, pondspice Litsea aestivalis, pondspice Persea borbonia, red bay
Avocado, Persea americana L., is the most important agricultural suscept of laurel wilt
Avocado, Persea americana L., is the most important agricultural suscept of laurel wilt Grown/consumed by those in MesoAmerica for at least 9,000 years
Avocado, Persea americana L., is the most important agricultural suscept of laurel wilt Grown/consumed by those in MesoAmerica for at least 9,000 years Global production exceeds 2 million metric tons, most of which is consumed locally (not exported); Mexico is leading producer
Avocado, Persea americana L., is the most important agricultural suscept of laurel wilt Three botanical races: Mexican (M), P. americana var. drymifolia Guatemalan (G), P. americana var. guatemalensis West Indian (WI), P. americana var. americana
Avocado, Persea americana L., is the most important agricultural suscept of laurel wilt Three botanical races: Mexican (M), P. americana var. drymifolia Guatemalan (G), P. americana var. guatemalensis West Indian (WI), P. americana var. americana Each race and hybrids thereof, are used commercially. Those in Florida are most often WI or WIxG hybrids
Reed Pinkerton Mex 5 Simmonds Choquette Brogdon Schnell et al. 2004
Avocado, Persea americana L., is the most important agricultural suscept of laurel wilt Three botanical races: Mexican (M), P. americana var. drymifolia Guatemalan (G), P. americana var. guatemalensis West Indian (WI), P. americana var. americana Each race and hybrids thereof, are used commercially. Those in Florida are most often WI or WIxG hybrids Cultivars chosen for LW studies have been genetically diverse and are used commercially in Florida
Gainesville UF, main campus DPI quarantine facility Gainesville Homestead Tropical Research & Education Center Citra Plant Science Research & Education Unit
Florida Division of Plant Industry Quarantine facilities Gainesville 30 August 2007 Grafted avocados 1 gal: Brogdon (MxGxWI), Reed (G) & Simmonds (WI) 7 gal: Simmonds (WI) Three isolates of Raffaelea lauricola Ft. George, Brevard Co., and HH5
One flap inoculation per plant above graft union and wrapped with Parafilm
20 days after inoculation
5 4 3 2 (dead) (severe) (moderate) (slight)
Results - DPI Cultivar Mean disease severity (1-5) /treatment Mock Ft. G Brevard HH 5 Brogdon, 3 gal 1.0 a 2.0 a 1.8 a 1.0 a Reed, 3 gal Simmonds, 3 gal 1.0 b 2.0 a 1.8 ab 1.0 b 1.0 b 2.0 a 2.3 a 1.3 b Simmonds, 7 gal 1.0 b 4.2 a 4.4 a 1.0 b
Results - DPI Cultivar Mean disease severity (1-5) /treatment Mock Ft. G Brevard HH 5 Brogdon, 3 gal 1.0 ns 2.0 ns 1.8 ns 1.0 ns Reed, 3 gal 1.0 ns 2.0 ns 1.8 ns 1.0 ns Simmonds, 3 gal 1.0 ns 2.0 ns 2.3 ns 1.3 ns ns *** *** ns Simmonds, 7 gal 1.0 4.2 4.4 1.0
Citra experiments As laurel wilt moved through Gainesville area, field work at Citra became possible Gainesville UF, main campus DPI quarantine facility Citra Plant Science Research & Education Unit
Citra experiments Four experiments established May 2008 1. Cultivar evaluation (11 commercial cvs) 2. Plant size (3gal sm, 3gal lg, 7gal & 15gal) 3. Inoculum dose/threshold (1 & 5 inoc pts; 6 cvs) 4. Isolate (four different isolates of R. lauricola)
Citra experiments Staging area, 30 April 2008, after overnight transfer from Homestead in 28 moving van Irrigation after planting Planting team, 30 April Inoculation team, 1 May
Citra experiments Results, 6 wk post-inoculation Experiment 1 Cultivar susceptibility Cultivar (pedigree) Mean severity Miguel (GxWI) Simmonds (WI) Lula (GxWI) Donnie (WI) Bernecker (WI) Monroe (GxWI) Brogdon (MxGxWI) Choquette (GxWI) Catalina (WI) Florida Haas (MxG) Hall (GxWI) 3.3 a 3.2 a 3.0 ab 2.6 abc 2.6 abc 2.4 abcd 2.0 abcd 1.8 bcd 1.8 bcd 1.6 cd 1.3 d 1-5 scale, DMRT, P<0.05 These are preliminary results!
Citra experiments Experiment 2 Plant Size (Simmonds) 4 sizes 3 gallon sm 3 gallon lg 7 gallon 15 gallon
Citra experiments Experiment 2 Plant Size (Simmonds (WI) Disease severity y=14.4+3.3x P>0.01 r 2 =0.35 Stem diameter (mm)
Citra experiments Experiment 3 Inoculum dose/theshhold Six cultivars Small 3 gallon plants Inoculated with Avocado B isolate of R. lauricola 1 or 5 times 1 time
Citra experiments Experiment 3 Inoculum dose/theshhold Cultivar Mean disease severity 1 inoc pts 5 inoc pts Chouquette (GxWI) 2.3 3.0 Donnie (WI) 1.3 2.0 Haas (GxM) 1.3 1.3 Lula (GxWI) 1.3 1.7 Monroe (GxWI) 1.3 1.7 Simmonds (WI) 2.3 2.0 ns
Rapid detection of R. lauricola 1000 Fluorescence (norm) 100 10 1 0 2 4 6 8 10 12 14 16 18 20 22 Cycle 24 26 28 30 32 34 36 38 40 Realtime PCR Ct[Cycle] 40 35 30 25 20 15 1.0E-05 0.001 0.1 10 Amount[ng] Standards Unknow ns
Conclusions (to date) Plant size has profound effect on LW development: only large avocado plants develop significant disease in two different experiments
Conclusions (to date) Plant size has profound effect on LW development: only large avocado plants develop significant disease, and multiple inoculations did not significantly increase disease severity in small plants (screening is complicated by availability and expense of large plants)
Conclusions (to date) Plant size has profound effect on LW development: only large avocado plants develop significant disease, and multiple inoculations did not significantly increase disease severity in small plants (screening is complicated by availability and expense of large plants) There may be genotypic tolerance to LW in avocado that is not related to botanical race this work must be repeated
Conclusions (to date) Plant size has profound effect on LW development: only large avocado plants develop significant disease, and multiple inoculations did not significantly increase disease severity in small plants (screening is complicated by availability and expense of large plants) There may be genotypic tolerance to LW in avocado that is not related to botanical race Genetic and pathogenic variation in R. lauricola?
Conclusions (to date) Plant size has profound effect on LW development: only large avocado plants develop significant disease, and multiple inoculations did not significantly increase disease severity in small plants (screening is complicated by availability and expense of large plants) There may be genotypic tolerance to LW in avocado that is not related to botanical race Genetic and pathogenic variation in R. lauricola? ex. HH5 isolates significantly less virulent than other isolates on Reed and Simmonds
Future work Refine screening protocols (reduce response variability and speed of disease development)
Future work Refine screening protocols (reduce response variability and speed of disease development) Repeat screening work, identify responses of different genotypes (are differences observed to date real/repeatable?)
Future work Refine screening protocols (reduce response variability and speed of disease development) Repeat screening work, identify responses of different genotypes (are differences observed to date real/repeatable?) Examine other species in Lauraceae for disease response; many of which are important landscape and ornamentals in Florida, south of the current range of LW
Hosts Xyleborus glabratus Asia Xyleborus glabratus USA Raffaelea lauricola Umbellularia californica Leucaena glauca Shorea robusta Lithocarpus edulis Angiosperms (http://www.life.uiuc.edu/ib/335/apgii.jpg) Lindera latifolia Litsea elongata Phoebe lanceolata Lauraceae (Chanderali et al., 2001) Cinnamomum jensenianum Cinnamomum camphora Sassafras albidum Lindera benzoin Lindera melissifolia Lindera strychnifolia Litsea aestivalis Phoebe sp. Machilus thunbergii Persea americana Persea borbonia Persea palustris
Order Family Species Common name Magnoliales Magnoliaceae Liriodendron tulipifera Annonaceae Magnolia grandiflora Magnolia virginiana Michelia alba Michelia champaca Annona squamosa Native to? Use tulip polar yes timber, ornamental southern magnolia sweet bay magnolia white champaca yes yes no ornamental ornamental ornamental champak no ornamental sugar apple no commercial fruit crop Annona glabra pond apple yes Asimina triloba paw paw yes ornamental Cananga ylang ylang no ornamental ordorata Polyalthia Asoka tree no ornamental longifolia Rollinia deliciosa biriba no commercial fruit crop Laurales Lauraceae Cassytha filiformis dodder yes weed Cinnamomum verum cinnamon no ornamental, spice Laurus azorica no ornamental Laurus no ornamental novocanariensis Licaria trianda yes ornamental Sassafras tsumu no ornamental Piperales Piperaceae Peperomia no ornamental clusiifolia Peperomia obtusifolia no ornamental Piper nigrum black pepper no ornamental, spice
Thanks to following for their support Florida Avocado Committee University of Florida, IFAS Vice President Pine Island Nursery Zill High Performance Plants, Inc. USDA, T-STAR Special Grants