Laurel wilt: A destructive new disease in the southeastern US. Randy Ploetz University of Florida Tropical Research & Education Center Homestead, FL

Transcription

1 Laurel wilt: A destructive new disease in the southeastern US Randy Ploetz University of Florida Tropical Research & Education Center Homestead, FL

2 Chronology An exotic ambrosia beetle, Xyleborus glabratus, detected in Port Wentworth, 2002

3 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

4 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

5 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

6 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

7 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

8

9 Soultis et al. 2000

10 Piper nigrum, black pepper Magnolia grandiflora

11 The Laurels Chanderbali et al. 2001

12 The Laurels Some species are important sources of timber Chanderbali et al. 2001

13 The Laurels Ocotea porosa Ocotea rubra Ocotea ballata Chanderbali et al. 2001

14 The Laurels Some are important sources of spices and condiments Chanderbali et al. 2001

15 The Laurels Umbellaria californica Cinnamomum camphor Cinnamomum verum Laurus nobilis

16 The Laurels There is an important commercial fruit species in the family, Chanderbali et al. 2001

17 The Laurels Persea americana

18 The Laurels and they are ecosystem components in the continental US Chanderbali et al. 2001

19 The Laurels Nectandra coricea Sassafras albidum Persea borbonia

20 The Laurels and they are ecosystem components in the continental US, as well as tropical America Chanderbali et al. 2001

21 The Laurels

22 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

23 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

24 Avocado, Persea americana L., is the most important agricultural suscept of laurel wilt

25 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

26 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

27 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

28 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

29 Reed Pinkerton Mex 5 Simmonds Choquette Brogdon Schnell et al. 2004

30 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

31 Gainesville UF, main campus DPI quarantine facility Gainesville Homestead Tropical Research & Education Center Citra Plant Science Research & Education Unit

32 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

33 One flap inoculation per plant above graft union and wrapped with Parafilm

34 20 days after inoculation

35 (dead) (severe) (moderate) (slight)

36 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

37 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

38 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

39 Citra experiments Four experiments established May 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)

40 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

41 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!

42 Citra experiments Experiment 2 Plant Size (Simmonds) 4 sizes 3 gallon sm 3 gallon lg 7 gallon 15 gallon

43 Citra experiments Experiment 2 Plant Size (Simmonds (WI) Disease severity y= x P>0.01 r 2 =0.35 Stem diameter (mm)

44 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

45 Citra experiments Experiment 3 Inoculum dose/theshhold Cultivar Mean disease severity 1 inoc pts 5 inoc pts Chouquette (GxWI) Donnie (WI) Haas (GxM) Lula (GxWI) Monroe (GxWI) Simmonds (WI) ns

46 Rapid detection of R. lauricola 1000 Fluorescence (norm) Cycle Realtime PCR Ct[Cycle] E Amount[ng] Standards Unknow ns

47 Conclusions (to date) Plant size has profound effect on LW development: only large avocado plants develop significant disease in two different experiments

48 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)

49 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

50 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?

51 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

52 Future work Refine screening protocols (reduce response variability and speed of disease development)

53 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?)

54 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

55 Hosts Xyleborus glabratus Asia Xyleborus glabratus USA Raffaelea lauricola Umbellularia californica Leucaena glauca Shorea robusta Lithocarpus edulis Angiosperms ( 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

56 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

57 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