Fusarium Dieback in California: another ambrosia beetle associated disease of avocado and urban forest A. Eskalen1, S.C. Lynch1, F. Na, J.S. Mayorquin1, J.D. Carrillo1, A. Lira2, T. Atkinson3 1 Department of Plant Pathology and Microbiology, University of California, Riverside, CA 92521 2 Ecology and evolutionary biology, Inecol, Mexico 3Ecology 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 Polyphagous Shot Hole Borer A.Eskalen PSHB Fusarium Graphium Paracremonium euwallaceae pembeum Los Angeles Co Euwallacea sp. euwallaceae Orange Co (Freeman et al.2013) (Lynch et al. 2015 (Lynch et al. 2015) San Bernardino Co Riverside Co Ventura Co. Kuroshio Shot Hole Borer KSHB San Diego Co Euwallacea sp. Fusarium sp. Graphium sp. Orange Co (New species) (New species) Santa Barbara Co San Luis Obispo Co Koch’s Postulates – Pathogenicity test Avocado Box Elder Persea americana Acer negundo 16 A 14 12 B B 10 8 6 Lesion Length (cm) 4 2 C 0 Fusarium euwallaceae Graphium euwallaceaeeuwallaceae ParacremoniumAcremonium sp.pembeum Control 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 10 Fusarium euwallaceae 9 Paracremonium pembeum 8 Graphium euwallaceae 7 6 5 4 Fungal diameter (cm) 3 2 1 0 5 10 15 20 25 30 35 40 Temperature °C Fusarium dieback and symbiotic fungal pathogens +51&80:;%'718<:1&4:=5'':>%$# !"$%&'()* !"$%&'()* $*A(;%2#J'&#QPB$'5B: '+6B'S# N7F)(B)8 Q=5$' *$0B*2+S Number of reproductive hosts that beetle/fungus can produce their offsprings 1. Box elder (Acer negundo)* 25. Coral tree (Erythrina corallodendon) 2. California sycamore (Platanus racemosa) * 26. Blue palo verde (Cercidium floridum)* 3. London plane (Platanus x acerfolia) 27. Moreton Bay Chestnut (Castanospermum australe) 4. Red willow (Salix laevigata) * 28. Brea (Cercidium sonorae) 5. Black willow (Salix gooddingii)* 29. Mesquite (Prosopis articulata)* 6. Arroyo willow (Salix lasiolepis) * 30. Weeping willow (Salix babylonica) 7. Cottonwood (Populus fremontii)* 31. Chinese holly (Ilex cornuta) 8. Black poplar (Populus nigra)* 32. Camelia (Camellia semiserrata) 9. Black cottonwood (Populus trichocarpa)* 33. Acacia (Acacia spp.) 10. Mimosa (Albizia julibrissin) 34. Liquidambar (Liquidambar styraciflua) 11. English Oak (Quercus robur) 35. Red Flowering Gum (Eucalyptus ficifolia) 12. Engelmann oak (Quercus engelmannii)* 36. Japanese wisteria (Wisteria floribunda) 13. Valley oak (Quercus lobata) * 37. Goodding's black willow (Salix gooddingii)* 14. Palo verde (Parkinsonia aculeata) * 38. Tree of heaven (Ailanthus altissima) 15. Big leaf maple (Acer macrophyllum)* 39. Kurrajong (Brachychiton populneus) 16. Japanese maple (Acer palmatum) 40. Black mission fig (Ficus carica) 17. Castorbean (Ricinus communis) 41. Japanese beech (Fagus crenata) 18. Canyon Live oak (Quercus chrysolepis)* 42. Dense logwood (Xylosma congestum) 19.Avocado (Persea americana 43. Mule Fat (Baccharis salicifolia)* 20.Trident maple (Acer buergerianum) 44. Carrotwood (Cupaniopsis anacardioides) 21.Coast live oak (Quercus agrifolia) 45. California buckeye (Aesculus californica)* 22.White Alder (Alnus rhombifolia)* 46. Mule Fat (Baccharis salicifolia) * 23.Titoki (Alectryon excelsus) 47. Kentia Palm (Howea forsteriana) 24.Cork Oak (Quercus suber) 48. King Palm (Ptychosperma elegans) Eskalen and Lynch, 2016. Unpublished data Urban Forests Impacted Parks Backyard Trees 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 Park Carbon Canyon Beetle attack incidence on an infested sycamore tree overtime 250 200 Mean(attacks/m^2) vs. Time 150 attacks/m^2 100 50 0 Aug '15 Sep Oct Nov Dec Jan Feb Time Mar Apr May Jun Jul Aug '16 Tijuana River Valley Before and After Pictures May 2015 Feb 2016 Boland, 2016 Control Strategies Laboratory Fungicide Screening Experiment EC50 Values Azoxystrobin No Inhibition Triadimefon No Inhibition Trifloxystrobin No Inhibition Fluxapyroxad No Inhibition Pyrimethanil d Mycobutanil c Fluopyram c Triflumizole Treatment b 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 This slide is blank on purpose. Please see next slide. 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 Collaborators 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 www.eskalenlab.ucr.edu.