Fusarium Dieback in California: another ambrosia beetle associated disease of avocado and urban forest A. Eskalen 1, S.C. Lynch 1, F. Na, J.S. Mayorquin 1, J.D. Carrillo 1, A. Lira 2, T. Atkinson 3 1 Department of Plant Pathology and Microbiology, University of California, Riverside, CA 92521 2 Ecology and evolutionary biology, Inecol, Mexico 3 Ecology of ambrosia beetles from University of Texas Avocado Laurel Wilt Summit, Homestead, Florida Nov 3-4, 2016
Outline Overview Current reproductive hosts of SHB Current situation on avocado in California Current situation on urban forest in California Control strategies and best management practices on avocado
Polyphagous and Kuroshio Shot Hole Borers and their symbiotic fungi Los Angeles Co Orange Co San Bernardino Co Riverside Co Ventura Co. A.Eskalen Polyphagous Shot Hole Borer PSHB Euwallacea sp. Fusarium euwallaceae Graphium euwallaceae Paracremonium pembeum (Freeman et al.2013) (Lynch et al. 2015 (Lynch et al. 2015) Kuroshio Shot Hole Borer KSHB San Diego Co Orange Co Santa Barbara Co San Luis Obispo Co Euwallacea sp. Fusarium sp. (New species) Graphium sp. (New species)
Koch s Postulates Pathogenicity test Avocado Box Elder Persea americana Acer negundo 16 A Lesion Length (cm) 14 12 10 8 6 4 B B 2 0 Fusarium euwallaceae Graphium euwallaceae Paracremonium Acremonium sp. pembeum Control C Mean lesion lengths on avocado and box elder shoots inoculated with isolates of Fusarium euwallaceae, Graphium euwallaceae and Paracremonium pembeum. Vertical lines represent standard error of the mean according to Fisher protected Least significant difference (LSD) mean separation test at α = 0.05. Lynch and Eskalen, 2016. Mycologia, 108(2), pp.313-329
Growth rate of symbiotic fungi in different temperature Fungal diameter (cm) 0 10 9 8 7 6 5 4 3 2 1 Fusarium euwallaceae Paracremonium pembeum Graphium euwallaceae 5 10 15 20 25 30 35 40 Temperature C
Fusarium dieback and symbiotic fungal pathogens
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Eskalen and Lynch, 2016. Unpublished data Number of reproductive hosts that beetle/fungus can produce their offsprings 1. Box elder (Acer negundo)* 2. California sycamore (Platanus racemosa) * 3. London plane (Platanus x acerfolia) 4. Red willow (Salix laevigata) * 5. Black willow (Salix gooddingii)* 6. Arroyo willow (Salix lasiolepis) * 7. Cottonwood (Populus fremontii)* 8. Black poplar (Populus nigra)* 9. Black cottonwood (Populus trichocarpa)* 10. Mimosa (Albizia julibrissin) 11. English Oak (Quercus robur) 12. Engelmann oak (Quercus engelmannii)* 13. Valley oak (Quercus lobata) * 14. Palo verde (Parkinsonia aculeata) * 15. Big leaf maple (Acer macrophyllum)* 16. Japanese maple (Acer palmatum) 17. Castorbean (Ricinus communis) 18. Canyon Live oak (Quercus chrysolepis)* 19.Avocado (Persea americana 20.Trident maple (Acer buergerianum) 21.Coast live oak (Quercus agrifolia) 22.White Alder (Alnus rhombifolia)* 23.Titoki (Alectryon excelsus) 24.Cork Oak (Quercus suber) 25. Coral tree (Erythrina corallodendon) 26. Blue palo verde (Cercidium floridum)* 27. Moreton Bay Chestnut (Castanospermum australe) 28. Brea (Cercidium sonorae) 29. Mesquite (Prosopis articulata)* 30. Weeping willow (Salix babylonica) 31. Chinese holly (Ilex cornuta) 32. Camelia (Camellia semiserrata) 33. Acacia (Acacia spp.) 34. Liquidambar (Liquidambar styraciflua) 35. Red Flowering Gum (Eucalyptus ficifolia) 36. Japanese wisteria (Wisteria floribunda) 37. Goodding's black willow (Salix gooddingii)* 38. Tree of heaven (Ailanthus altissima) 39. Kurrajong (Brachychiton populneus) 40. Black mission fig (Ficus carica) 41. Japanese beech (Fagus crenata) 42. Dense logwood (Xylosma congestum) 43. Mule Fat (Baccharis salicifolia)* 44. Carrotwood (Cupaniopsis anacardioides) 45. California buckeye (Aesculus californica)* 46. Mule Fat (Baccharis salicifolia) * 47. Kentia Palm (Howea forsteriana) 48. King Palm (Ptychosperma elegans)
Urban Forests Impacted Backyard Trees Parks Street Trees Golf Courses
California Native Plant Communities Impacted Mixed Evergreen Forests Oak Woodlands Foothill Woodlands Riparian
Current Situation on avocado in California
Monitoring infested avocado groves Total groves surveyed: 26 1 ha (2.47 acres) monitoring plot established Examined every tree within the plot Total trees surveyed: 4,346 x 3 times
SHB infestation habit on avocado in California
Branch dieback on Avocado
Sugar exudate and internal symptoms on avocado branch
Beetle attack on branch collar and pruning wounds on avocado
Current Situation in Urban Forest in California
Damage on Landscape trees
Beetle attack incidence on an infested sycamore tree overtime 250 Mean(attacks/m^2) vs. Time Park Carbon Canyon 200 attacks/m^2 150 100 50 0 Aug '15 Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug '16 Time
Boland, 2016 Tijuana River Valley Before and After Pictures May 2015 Feb 2016
Control Strategies
Laboratory Fungicide Screening Experiment EC50 Values Azoxystrobin No Inhibition Triadimefon No Inhibition Trifloxystrobin No Inhibition Fluxapyroxad No Inhibition Pyrimethanil d Treatment Mycobutanil Fluopyram Triflumizole b c c Propiconazole ab Thiabendazole ab Tebuconazole a Pyraclostrobin a Metconazole a 0 1 2 3 4 5 EC50 Values (ug/ml)
Field Pesticide Trial on Avocado Tree IV injection system Quick-Jet Air injection system
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Best Management Practices on Avocado If the infestation is on the branch collar, cut into branch collar. Spray pruning wound with either Bifenthrin or 2% (Bacillus subtilis).
Best Management Practices on Avocado Cont. Chip infested wood on-site to a size of one inch or smaller. Solarize chipping material using clear plastic tarp for several months Compost chipping material and then use as mulch in the grove If the branch is too large to chip Fumigation with phosphine gas (Arpaia and Rios, 2015) Don't move infested plant material without chipping and solarizing
California Avocado Commission U.S. Forest Service, OC Parks, UC Irvine, UC ANR, USDA Farm Bill, Arborjet, Mauget, USDA Forest Service, Cal-Fire, Huntington botanical garden and LA arboretum, UC Mexus, Inecol, Mexico. Frederique Revenchon, Inecol, Mexico Ben Faber, Farm Advisor, Ventura County, CA\ Richard Demerjian, UC Irvine Sonia Rios, UCCE Farm Advisor, San Diego Sabrina Drill, UCCE LA and Ventura Dan Berry, Huntington Botanical Garden, Gary Bender, UCCE, Emeritus, San Diego Co. Janis Gonzales, UCCE San Diego Jim Folsom, Huntington Botanical Garden Jiri Hulcr, Univ. of Florida Kerry O Donnell, NCUR-ARS-USDA Mary Lu Arpaia, UC Riverside Kim Corella, Cal Fire Tom Smith, Cal Fire Joe Barcinas, PCA Tom Roberts, PCA Mathew Hand, PCA Linda Bellamy, Venture Susan Frankel, USDA Forest Service Tom Atkinson, University of Texas Sean Feirer, UCANR Jim Downer, UCCE Ventura Collaborators www.eskalenlab.ucr.edu