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Pierluigi Bonello - One of the best experts on this subject based on the ideXlab platform.
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incidence and distribution of resistance in a coast Live Oak sudden Oak death pathosystem
Proceedings of the seventh sudden oak death science and management symposium: healthy plants in a world with Phytophthora. Gen. Tech. Rep. PSW-GTR-268, 2020Co-Authors: Anna O Conrad, Brice A Mcpherson, David L Wood, Pierluigi Bonello, Katherine M Damico, Horacio D LopeznicoraAbstract:In coastal California, infection by the pathogen Phytophthora ramorum, causal agent of sudden Oak death, results in extensive mortality of native Oak species including Quercus agrifolia (coast Live Oak). However, apparently resistant Q. agrifolia have been observed within native populations. In this study (Conrad and others 2019), we monitored disease progression from 2010 to 2017 in Q. agrifolia artificially inoculated with P. ramorum and disease incidence in Q. agrifolia left to become naturally infected in the same stand. After seven years, 61% of artificially inoculated Q. agrifolia died while 27% appeared to be resistant (i.e. in remission, no longer showing active symptoms of P. ramorum infection) (N = 149). In addition, 13% of noninoculated Q. agrifolia showed symptoms of natural P. ramorum infection, e.g. bleeding exudate (N = 423). Canker length measured approximately one year following inoculation was a significant predictor of Q. agrifolia resistance and survival (P < 0.001). Canker length was also used to examine the distribution of resistant and susceptible Q. agrifolia across the landscape using inverse distance weighted analysis. This analysis revealed resistant and susceptible Q. agrifolia are aggregated, suggesting resistance is a heritable trait. A better understanding of the amount and distribution of resistant Q. agrifolia within native populations can be used to facilitate the restoration of disturbed habitats and identify sources of germplasm for future breeding efforts.
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disease incidence and spatial distribution of host resistance in a coast Live Oak sudden Oak death pathosystem
Forest Ecology and Management, 2019Co-Authors: Anna O Conrad, Brice A Mcpherson, David L Wood, Katherine M Damico, Horacio D Lopeznicora, Pierluigi BonelloAbstract:Abstract Sudden Oak death (SOD) results in extensive mortality of native populations of red Oak (Quercus spp.) and tanOak (Notholithocarpus densiflorus) in coastal California and Oregon. The pathogen, Phytophthora ramorum, causes a syndrome in Q. agrifolia (coast Live Oak, CLO) characterized by bleeding stem cankers, attacks by bark and ambrosia beetles, and development of the endophytic fungus, Annulohypoxylon thouarsianum. The study examined disease incidence and resistance in CLO within Northern California stands that had no apparent prior exposure to the pathogen. Seven years after artificial inoculation of mature trees distributed between two separate stands in a California wildland, 27% of CLO expressed resistance to P. ramorum, while 61% died (N = 149). The remaining trees were aLive but symptomatic. External and subcortical canker lengths, measured approximately one year post-inoculation, were significant predictors of CLO resistance and survival seven years post-inoculation. Spatial analysis also revealed that variation in CLO susceptibility to P. ramorum is aggregated on the landscape, suggesting that more resistant and susceptible trees tend to co-occur and that resistance is a heritable trait. From 2011 to 2017 the incidence of natural infections in a second cohort of non-inoculated trees increased from 2.0% (N = 447) to 13.2% (N = 423). Altogether, these findings suggest that estimating the frequency and determining the spatial distribution of resistant trees on the landscape can be used to identify sites that should be targeted for germplasm collection and habitat conservation.
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identification of quercus agrifolia coast Live Oak resistant to the invasive pathogen phytophthora ramorum in native stands using fourier transform infrared ft ir spectroscopy
Frontiers in Plant Science, 2014Co-Authors: Anna O Conrad, Brice A Mcpherson, David L Wood, Luis E Rodriguezsaona, Pierluigi BonelloAbstract:Over the last two decades coast Live Oak (CLO) dominance in many California coastal ecosystems has been threatened by the alien invasive pathogen Phytophthora ramorum, the causal agent of sudden Oak death. In spite of high infection and mortality rates in some areas, the presence of apparently resistant trees has been observed, including trees that become infected but recover over time. However, identifying resistant trees based on recovery alone can take many years. The objective of this study was to determine if Fourier-transform infrared (FT-IR) spectroscopy, a chemical fingerprinting technique, can be used to identify CLO resistant to P. ramorum prior to infection. Soft independent modeling of class analogy identified spectral regions that differed between resistant and susceptible trees. Regions most useful for discrimination were associated with carbonyl group vibrations. Additionally, concentrations of two putative phenolic biomarkers of resistance were predicted using partial least squares regression; >99% of the variation was explained by this analysis. This study demonstrates that chemical fingerprinting can be used to identify resistance in a natural population of forest trees prior to infection with a pathogen. FT-IR spectroscopy may be a useful approach for managing forests impacted by sudden Oak death, as well as in other situations where emerging or existing forest pests and diseases are of concern.
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phytophthora ramorum in coast Live Oak search for resistance and mechanisms
In: Frankel S.J.; Kliejunas J.T.; Palmieri K.M.; Alexander J.M. tech. coords. Proceedings of the sudden oak death fifth science symposium. Gen. Tech. , 2013Co-Authors: Brice A Mcpherson, David L Wood, Sylvia R Mori, Anna O Conrad, Pierluigi BonelloAbstract:Despite the presence of Phytophthora ramorum in northern and central California forests since at least 1994, asymptomatic coast Live Oaks (Quercus agrifolia Nee) still remain in heavily infested stands. Coast Live Oak infection and mortality rates of 5 percent y-1 and 3 percent y-1, respectively, observed in long-term monitoring plots in Marin County, California give no indication that individual trees appear to evade infection. In some study plots, more than 50 percent of the mature coast Live Oaks have died since 2000.
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metabolite profiling to predict resistance to phytophthora ramorum in natural populations of coast Live Oak
In: Frankel S.J.; Kliejunas J.T.; Palmieri K.M.; Alexander J.M. tech. coords. Proceedings of the sudden oak death fifth science symposium. Gen. Tech. , 2013Co-Authors: Anna O Conrad, Brice A Mcpherson, David L Wood, Sylvia R Mori, Stephen O Opiyo, Pierluigi BonelloAbstract:Sudden Oak death, caused by the invasive oomycete pathogen Phytophthora ramorum, continues to shape the dynamics of coastal populations of Oak (Quercus spp.) and tanOak (Notholithocarpus densiflorus (Hook. & Arn.) Manos, Cannon & S.H. Oh) in California and tanOak in southwestern Oregon. Over the last decade, high mortality rates have been reported in natural populations of coast Live Oak (CLO; Quercus agrifolia Nee) in California, raising concerns for the integrity of important coastal ecosystems. However, it is now recognized that in spite of high infection and mortality rates, asymptomatic CLO have persisted.
David L Wood - One of the best experts on this subject based on the ideXlab platform.
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incidence and distribution of resistance in a coast Live Oak sudden Oak death pathosystem
Proceedings of the seventh sudden oak death science and management symposium: healthy plants in a world with Phytophthora. Gen. Tech. Rep. PSW-GTR-268, 2020Co-Authors: Anna O Conrad, Brice A Mcpherson, David L Wood, Pierluigi Bonello, Katherine M Damico, Horacio D LopeznicoraAbstract:In coastal California, infection by the pathogen Phytophthora ramorum, causal agent of sudden Oak death, results in extensive mortality of native Oak species including Quercus agrifolia (coast Live Oak). However, apparently resistant Q. agrifolia have been observed within native populations. In this study (Conrad and others 2019), we monitored disease progression from 2010 to 2017 in Q. agrifolia artificially inoculated with P. ramorum and disease incidence in Q. agrifolia left to become naturally infected in the same stand. After seven years, 61% of artificially inoculated Q. agrifolia died while 27% appeared to be resistant (i.e. in remission, no longer showing active symptoms of P. ramorum infection) (N = 149). In addition, 13% of noninoculated Q. agrifolia showed symptoms of natural P. ramorum infection, e.g. bleeding exudate (N = 423). Canker length measured approximately one year following inoculation was a significant predictor of Q. agrifolia resistance and survival (P < 0.001). Canker length was also used to examine the distribution of resistant and susceptible Q. agrifolia across the landscape using inverse distance weighted analysis. This analysis revealed resistant and susceptible Q. agrifolia are aggregated, suggesting resistance is a heritable trait. A better understanding of the amount and distribution of resistant Q. agrifolia within native populations can be used to facilitate the restoration of disturbed habitats and identify sources of germplasm for future breeding efforts.
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disease incidence and spatial distribution of host resistance in a coast Live Oak sudden Oak death pathosystem
Forest Ecology and Management, 2019Co-Authors: Anna O Conrad, Brice A Mcpherson, David L Wood, Katherine M Damico, Horacio D Lopeznicora, Pierluigi BonelloAbstract:Abstract Sudden Oak death (SOD) results in extensive mortality of native populations of red Oak (Quercus spp.) and tanOak (Notholithocarpus densiflorus) in coastal California and Oregon. The pathogen, Phytophthora ramorum, causes a syndrome in Q. agrifolia (coast Live Oak, CLO) characterized by bleeding stem cankers, attacks by bark and ambrosia beetles, and development of the endophytic fungus, Annulohypoxylon thouarsianum. The study examined disease incidence and resistance in CLO within Northern California stands that had no apparent prior exposure to the pathogen. Seven years after artificial inoculation of mature trees distributed between two separate stands in a California wildland, 27% of CLO expressed resistance to P. ramorum, while 61% died (N = 149). The remaining trees were aLive but symptomatic. External and subcortical canker lengths, measured approximately one year post-inoculation, were significant predictors of CLO resistance and survival seven years post-inoculation. Spatial analysis also revealed that variation in CLO susceptibility to P. ramorum is aggregated on the landscape, suggesting that more resistant and susceptible trees tend to co-occur and that resistance is a heritable trait. From 2011 to 2017 the incidence of natural infections in a second cohort of non-inoculated trees increased from 2.0% (N = 447) to 13.2% (N = 423). Altogether, these findings suggest that estimating the frequency and determining the spatial distribution of resistant trees on the landscape can be used to identify sites that should be targeted for germplasm collection and habitat conservation.
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impact of the goldspotted Oak borer agrilus auroguttatus on the health of coast Live Oak before and after treatment with two systemic insecticides
Pest Management Science, 2015Co-Authors: Yigen Chen, David L Wood, Mary Louise Flint, Tom W Coleman, Joseph J Doccola, Donald M Grosman, Steven J SeyboldAbstract:BACKGROUND The invasive goldspotted Oak borer, Agrilus auroguttatus, is threatening the health and survival of Oak trees in San Diego County, California. From two sites in the core area of the infestation, we report a 2.5 year investigation of the impact of A. auroguttatus on coast Live Oak, Quercus agrifolia, before and after treatment with two systemic insecticides, emamectin benzoate (EB) and imidacloprid (IC). RESULTS None of the 446 survey trees died during the study. The crown dieback rating of most trees at both study sites remained unchanged, regardless of insecticide treatment. A higher cumulative increase in the number of A. auroguttatus emergence holes was observed on trees that were previously infested and on trees with larger diameters. Over the 2.5 year period, the new infestation rates of initially uninfested trees across the untreated and treated groups were 50% (EB) and 32% (IC), and neither EB nor IC treatment affected cumulative increases in the number of emergence holes. EB-injected trees did not have significant annual increases in the number of A. auroguttatus emergence holes at either 1.5 or 2.5 years compared with that at 0.5 years, whereas untreated trees had significant annual increases. Although IC-injected trees had a significantly greater annual increment in the number of emergence holes than untreated trees during the last year of the study, treated trees had significant reductions in annual increases in emergence holes at both 1.5 and 2.5 years compared with that at 0.5 years. Untreated trees had no significant reduction in the annual increase in emergence holes at 1.5 and 2.5 years. CONCLUSIONS A. auroguttatus preferentially attacked previously infested and larger (diameter at breast height > 15–30 cm) Oak trees, but the attacks led to very gradual changes in the health of the trees. Both EB and IC provided minor suppressive effects on A. auroguttatus emergence. Published 2014. This article is a U.S. Government work and is in the public domain in the USA.
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development of a management plan for coast Live Oak forests affected by sudden Oak death in east bay regional parks
Gen. Tech. Rep. PSW-GTR-251. Berkeley CA: U.S. Department of Agriculture Forest Service Pacific Southwest Research Station: 553-561, 2015Co-Authors: Brice A Mcpherson, Maggi Kelly, Joshua Oneill, Gregory Biging, David L WoodAbstract:The East Bay Regional Park District maintains the largest urban park system in the United States, comprising over 45 000 ha, and more than 1900 km of trails, with extensive forests bordering residential areas. Sudden Oak death (SOD), caused by the introduced oomycete Phytophthora ramorum, was first detected in a district park in 2001. Both increased fire risk and structural failure of large trees located near sites with heavy public usage are concerns for managers. Management requires reliable data about the location and severity of the disease. To produce disease incidence and risk maps, between 2008 and 2013 we placed 537 georeferenced 10-m radius fixed plots in Oak-bay stands in five parks in the East Bay Hills in the San Francisco Bay Area. We recorded data for all woody vegetation and the disease status of coast Live Oaks. Between 6 and 17 percent of coast Live Oaks were symptomatic and 2 to 8 percent were dead with symptoms of SOD. Infection rates of 2.1 and 3 percent/year were estimated for Tilden Park and Huckleberry Preserve, respectively. Logistic regression analysis for Anthony Chabot Park identified two predictors of SOD incidence: topographic moisture indices and increasing coast Live Oak diameter at breast height (1.37 m; DBH). Model results for the other parks confirm that DBH is a significant predictor of SOD infection. Modeled results for the other four parks found consistently significant associations between symptomatic coast Live Oak and remote sensing derived tasseled cap greenness vegetation index values, and distance to stream channels.
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effects of the goldspotted Oak borer agrilus auroguttatus on the health of coast Live Oak quercus agrifolia in southern california before and after treatment with two systemic insecticides
Gen. Tech. Rep. PSW-GTR-251. Berkeley CA: U.S. Department of Agriculture Forest Service Pacific Southwest Research Station: 345-347, 2015Co-Authors: Yigen Chen, David L Wood, Mary Louise Flint, Tom W Coleman, Joseph J Doccola, Donald M Grosman, Steven J SeyboldAbstract:The invasive goldspotted Oak borer, Agrilus auroguttatus (Coleoptera: Buprestidae), is threatening the health and survival of Oak trees in San Diego County, California (Flint and others 2013). The primary Oak species colonized and killed in this area include coast Live Oak (Quercus agrifolia), California black Oak (Quercus kelloggii), and canyon Live Oak (Quercus chrysolepis). The high amount of damage recorded on these hosts suggests that the association between A. auroguttatus and these Oaks is recent. Damage by A. auroguttatus in its native range in Arizona to Emory Oak (Quercus emoryi) and silverleaf Oak (Quercus hypoleucoides), is much less severe (Coleman and others 2012), suggesting a longer co-evolutionary relationship. Preventive and suppressive chemical treatment techniques have not previously been tested for the control of A. auroguttatus in California. Management activities have focused primarily on treatment of infested Oak wood (Jones and others 2013). We report on a 3.5-year investigation of the efficacy of two systemic insecticides, emamectin benzoate (EB) and imidacloprid (IC), for controlling A. auroguttatus in Q. agrifolia, in San Diego County.
Steven J Seybold - One of the best experts on this subject based on the ideXlab platform.
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impact of the goldspotted Oak borer agrilus auroguttatus on the health of coast Live Oak before and after treatment with two systemic insecticides
Pest Management Science, 2015Co-Authors: Yigen Chen, David L Wood, Mary Louise Flint, Tom W Coleman, Joseph J Doccola, Donald M Grosman, Steven J SeyboldAbstract:BACKGROUND The invasive goldspotted Oak borer, Agrilus auroguttatus, is threatening the health and survival of Oak trees in San Diego County, California. From two sites in the core area of the infestation, we report a 2.5 year investigation of the impact of A. auroguttatus on coast Live Oak, Quercus agrifolia, before and after treatment with two systemic insecticides, emamectin benzoate (EB) and imidacloprid (IC). RESULTS None of the 446 survey trees died during the study. The crown dieback rating of most trees at both study sites remained unchanged, regardless of insecticide treatment. A higher cumulative increase in the number of A. auroguttatus emergence holes was observed on trees that were previously infested and on trees with larger diameters. Over the 2.5 year period, the new infestation rates of initially uninfested trees across the untreated and treated groups were 50% (EB) and 32% (IC), and neither EB nor IC treatment affected cumulative increases in the number of emergence holes. EB-injected trees did not have significant annual increases in the number of A. auroguttatus emergence holes at either 1.5 or 2.5 years compared with that at 0.5 years, whereas untreated trees had significant annual increases. Although IC-injected trees had a significantly greater annual increment in the number of emergence holes than untreated trees during the last year of the study, treated trees had significant reductions in annual increases in emergence holes at both 1.5 and 2.5 years compared with that at 0.5 years. Untreated trees had no significant reduction in the annual increase in emergence holes at 1.5 and 2.5 years. CONCLUSIONS A. auroguttatus preferentially attacked previously infested and larger (diameter at breast height > 15–30 cm) Oak trees, but the attacks led to very gradual changes in the health of the trees. Both EB and IC provided minor suppressive effects on A. auroguttatus emergence. Published 2014. This article is a U.S. Government work and is in the public domain in the USA.
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effects of the goldspotted Oak borer agrilus auroguttatus on the health of coast Live Oak quercus agrifolia in southern california before and after treatment with two systemic insecticides
Gen. Tech. Rep. PSW-GTR-251. Berkeley CA: U.S. Department of Agriculture Forest Service Pacific Southwest Research Station: 345-347, 2015Co-Authors: Yigen Chen, David L Wood, Mary Louise Flint, Tom W Coleman, Joseph J Doccola, Donald M Grosman, Steven J SeyboldAbstract:The invasive goldspotted Oak borer, Agrilus auroguttatus (Coleoptera: Buprestidae), is threatening the health and survival of Oak trees in San Diego County, California (Flint and others 2013). The primary Oak species colonized and killed in this area include coast Live Oak (Quercus agrifolia), California black Oak (Quercus kelloggii), and canyon Live Oak (Quercus chrysolepis). The high amount of damage recorded on these hosts suggests that the association between A. auroguttatus and these Oaks is recent. Damage by A. auroguttatus in its native range in Arizona to Emory Oak (Quercus emoryi) and silverleaf Oak (Quercus hypoleucoides), is much less severe (Coleman and others 2012), suggesting a longer co-evolutionary relationship. Preventive and suppressive chemical treatment techniques have not previously been tested for the control of A. auroguttatus in California. Management activities have focused primarily on treatment of infested Oak wood (Jones and others 2013). We report on a 3.5-year investigation of the efficacy of two systemic insecticides, emamectin benzoate (EB) and imidacloprid (IC), for controlling A. auroguttatus in Q. agrifolia, in San Diego County.
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coast Live Oak quercus agrifolia susceptibility and response to goldspotted Oak borer agrilus auroguttatus injury in southern california
Forest Ecology and Management, 2011Co-Authors: Tom W Coleman, Nancy Grulke, Miles Daly, Cesar Godinez, Susan Schilling, Philip J Riggan, Steven J SeyboldAbstract:Oak mortality is often associated with a complex of decline factors. We describe the morphological and physiological responses of coast Live Oak, Quercus agrifolia Nee, in California to an invasive insect, the goldspotted Oak borer (GSOB), Agrilus auroguttatus Schaeffer (Coleoptera: Buprestidae), and evaluate drought as a potential inciting factor. Morphological traits of 356 trees were assessed and physiological traits of 70 of these were monitored intensively over one growing season. Morphological characteristics of tree health included crown thinning and dieback; bole staining resulting from larval feeding; density of GSOB adult exit holes; and holes caused by woodpecker feeding. These characteristics were used to rank GSOB infestation/injury into four classes, and taken together, they explained 87% of the variation in a principal component analysis. Drought stress on various size/age and infestation classes of Q. agrifolia was measured by assessing branchlet pre-dawn and solar noon xylem water potential, leaf cell turgor potential, and water use efficiency over one growing season. Both morphological and physiological traits were highly variable in mature and old growth trees. Early summer plant water status (branchlet xylem water potential and water use efficiency) was similar between uninfested and newly colonized trees, suggesting that GSOB are not pre-selecting drought-stressed Q. agrifolia for oviposition. By late summer, leaf water and cell turgor potentials were lower in infested than in uninfested mature trees, suggesting that GSOB infestation causes drought stress in these trees. Among the tree size/age classes, infested old growth trees exhibited the greatest change in water use efficiency over the growing season, and showed greater morphological injury symptoms of decline than infested mature trees. Morphological attributes of decline in Q. agrifolia associated with GSOB were correlated weakly with increasing physiological drought stress among infestation classes of trees. We propose that the collection of morphological responses of Q. agrifolia to GSOB described here can be used to monitor the future expansion of the GSOB distribution as well as the GSOB-induced decline of Q. agrifolia in California.
Brice A Mcpherson - One of the best experts on this subject based on the ideXlab platform.
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incidence and distribution of resistance in a coast Live Oak sudden Oak death pathosystem
Proceedings of the seventh sudden oak death science and management symposium: healthy plants in a world with Phytophthora. Gen. Tech. Rep. PSW-GTR-268, 2020Co-Authors: Anna O Conrad, Brice A Mcpherson, David L Wood, Pierluigi Bonello, Katherine M Damico, Horacio D LopeznicoraAbstract:In coastal California, infection by the pathogen Phytophthora ramorum, causal agent of sudden Oak death, results in extensive mortality of native Oak species including Quercus agrifolia (coast Live Oak). However, apparently resistant Q. agrifolia have been observed within native populations. In this study (Conrad and others 2019), we monitored disease progression from 2010 to 2017 in Q. agrifolia artificially inoculated with P. ramorum and disease incidence in Q. agrifolia left to become naturally infected in the same stand. After seven years, 61% of artificially inoculated Q. agrifolia died while 27% appeared to be resistant (i.e. in remission, no longer showing active symptoms of P. ramorum infection) (N = 149). In addition, 13% of noninoculated Q. agrifolia showed symptoms of natural P. ramorum infection, e.g. bleeding exudate (N = 423). Canker length measured approximately one year following inoculation was a significant predictor of Q. agrifolia resistance and survival (P < 0.001). Canker length was also used to examine the distribution of resistant and susceptible Q. agrifolia across the landscape using inverse distance weighted analysis. This analysis revealed resistant and susceptible Q. agrifolia are aggregated, suggesting resistance is a heritable trait. A better understanding of the amount and distribution of resistant Q. agrifolia within native populations can be used to facilitate the restoration of disturbed habitats and identify sources of germplasm for future breeding efforts.
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disease incidence and spatial distribution of host resistance in a coast Live Oak sudden Oak death pathosystem
Forest Ecology and Management, 2019Co-Authors: Anna O Conrad, Brice A Mcpherson, David L Wood, Katherine M Damico, Horacio D Lopeznicora, Pierluigi BonelloAbstract:Abstract Sudden Oak death (SOD) results in extensive mortality of native populations of red Oak (Quercus spp.) and tanOak (Notholithocarpus densiflorus) in coastal California and Oregon. The pathogen, Phytophthora ramorum, causes a syndrome in Q. agrifolia (coast Live Oak, CLO) characterized by bleeding stem cankers, attacks by bark and ambrosia beetles, and development of the endophytic fungus, Annulohypoxylon thouarsianum. The study examined disease incidence and resistance in CLO within Northern California stands that had no apparent prior exposure to the pathogen. Seven years after artificial inoculation of mature trees distributed between two separate stands in a California wildland, 27% of CLO expressed resistance to P. ramorum, while 61% died (N = 149). The remaining trees were aLive but symptomatic. External and subcortical canker lengths, measured approximately one year post-inoculation, were significant predictors of CLO resistance and survival seven years post-inoculation. Spatial analysis also revealed that variation in CLO susceptibility to P. ramorum is aggregated on the landscape, suggesting that more resistant and susceptible trees tend to co-occur and that resistance is a heritable trait. From 2011 to 2017 the incidence of natural infections in a second cohort of non-inoculated trees increased from 2.0% (N = 447) to 13.2% (N = 423). Altogether, these findings suggest that estimating the frequency and determining the spatial distribution of resistant trees on the landscape can be used to identify sites that should be targeted for germplasm collection and habitat conservation.
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development of a management plan for coast Live Oak forests affected by sudden Oak death in east bay regional parks
Gen. Tech. Rep. PSW-GTR-251. Berkeley CA: U.S. Department of Agriculture Forest Service Pacific Southwest Research Station: 553-561, 2015Co-Authors: Brice A Mcpherson, Maggi Kelly, Joshua Oneill, Gregory Biging, David L WoodAbstract:The East Bay Regional Park District maintains the largest urban park system in the United States, comprising over 45 000 ha, and more than 1900 km of trails, with extensive forests bordering residential areas. Sudden Oak death (SOD), caused by the introduced oomycete Phytophthora ramorum, was first detected in a district park in 2001. Both increased fire risk and structural failure of large trees located near sites with heavy public usage are concerns for managers. Management requires reliable data about the location and severity of the disease. To produce disease incidence and risk maps, between 2008 and 2013 we placed 537 georeferenced 10-m radius fixed plots in Oak-bay stands in five parks in the East Bay Hills in the San Francisco Bay Area. We recorded data for all woody vegetation and the disease status of coast Live Oaks. Between 6 and 17 percent of coast Live Oaks were symptomatic and 2 to 8 percent were dead with symptoms of SOD. Infection rates of 2.1 and 3 percent/year were estimated for Tilden Park and Huckleberry Preserve, respectively. Logistic regression analysis for Anthony Chabot Park identified two predictors of SOD incidence: topographic moisture indices and increasing coast Live Oak diameter at breast height (1.37 m; DBH). Model results for the other parks confirm that DBH is a significant predictor of SOD infection. Modeled results for the other four parks found consistently significant associations between symptomatic coast Live Oak and remote sensing derived tasseled cap greenness vegetation index values, and distance to stream channels.
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identification of quercus agrifolia coast Live Oak resistant to the invasive pathogen phytophthora ramorum in native stands using fourier transform infrared ft ir spectroscopy
Frontiers in Plant Science, 2014Co-Authors: Anna O Conrad, Brice A Mcpherson, David L Wood, Luis E Rodriguezsaona, Pierluigi BonelloAbstract:Over the last two decades coast Live Oak (CLO) dominance in many California coastal ecosystems has been threatened by the alien invasive pathogen Phytophthora ramorum, the causal agent of sudden Oak death. In spite of high infection and mortality rates in some areas, the presence of apparently resistant trees has been observed, including trees that become infected but recover over time. However, identifying resistant trees based on recovery alone can take many years. The objective of this study was to determine if Fourier-transform infrared (FT-IR) spectroscopy, a chemical fingerprinting technique, can be used to identify CLO resistant to P. ramorum prior to infection. Soft independent modeling of class analogy identified spectral regions that differed between resistant and susceptible trees. Regions most useful for discrimination were associated with carbonyl group vibrations. Additionally, concentrations of two putative phenolic biomarkers of resistance were predicted using partial least squares regression; >99% of the variation was explained by this analysis. This study demonstrates that chemical fingerprinting can be used to identify resistance in a natural population of forest trees prior to infection with a pathogen. FT-IR spectroscopy may be a useful approach for managing forests impacted by sudden Oak death, as well as in other situations where emerging or existing forest pests and diseases are of concern.
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phytophthora ramorum in coast Live Oak search for resistance and mechanisms
In: Frankel S.J.; Kliejunas J.T.; Palmieri K.M.; Alexander J.M. tech. coords. Proceedings of the sudden oak death fifth science symposium. Gen. Tech. , 2013Co-Authors: Brice A Mcpherson, David L Wood, Sylvia R Mori, Anna O Conrad, Pierluigi BonelloAbstract:Despite the presence of Phytophthora ramorum in northern and central California forests since at least 1994, asymptomatic coast Live Oaks (Quercus agrifolia Nee) still remain in heavily infested stands. Coast Live Oak infection and mortality rates of 5 percent y-1 and 3 percent y-1, respectively, observed in long-term monitoring plots in Marin County, California give no indication that individual trees appear to evade infection. In some study plots, more than 50 percent of the mature coast Live Oaks have died since 2000.
S C Lynch - One of the best experts on this subject based on the ideXlab platform.
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first report of geosmithia pallida causing foamy bark canker a new disease on coast Live Oak quercus agrifolia in association with pseudopityophthorus pubipennis in california
Plant Disease, 2014Co-Authors: S C Lynch, Joey S Mayorquin, D H Wang, Paul F Rugmanjones, Richard Stouthamer, Akif EskalenAbstract:Declining coast Live Oak (Quercus agrifolia) trees have been observed since 2012 throughout urban landscapes in Los Angeles, Orange, Riverside, Santa Barbara, Ventura, and Monterey counties in California. Symptoms causing branch dieback and tree death included a cinnamon-colored gum seeping through multiple 0.95-mm-diameter entry holes on the bole, followed by a prolific, cream-colored foamy liquid. Beneath the outer bark was phloem and xylem necrosis. Fifty 1- to 2.5-mm adult and larval beetles were collected. Adults fit the morphological description of Pseudopityophthorus pubipennis (western Oak bark beetle) (R. Rabaglia, personal communication), and ~800 bp of the mitochondrial COI gene was amplified for three beetles using primer pairs and methods previously described (2,3). All three sequences were identical (GenBank Accession Nos. KJ831289 to 91) and a BLAST search confirmed the closest match (94%) as P. pubipennis. Necrotic wood tissues collected from two trees in each county were cultured on potat...
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identification of new fungal pathogens of coast Live Oak in california
Plant Disease, 2013Co-Authors: S C Lynch, Paul J Zambino, Joey S Mayorquin, D H Wang, Akif EskalenAbstract:Lynch, S. C., Zambino, P. J., Mayorquin, J. S., Wang, D. H., and Eskalen, A. 2013. Identification of new fungal pathogens of coast Live Oak in California. Plant Dis. 97:1025-1036. A decline of coast Live Oak (Quercus agrifolia) has been observed throughout southern California. In this study, the identity and pathogenicity of non-Botryosphaeriaceae fungal species consistently recovered from necrotic tissues of branch and bleeding trunk canker samples from these locations were assessed. Species were identified morphologically and by comparison of the complete sequence of the internal transcribed spacer (ITS) of the ribosomal DNA to sequences available in GenBank. Phylogenetic analyses were then conducted using ITS and partial sequences of the β-tubulin and mitochondrial small ribosomal subunit genes for unknown species. Fungi recovered and identified included Fusarium solani, Phaeoacremonium mortoniae, Diatrypella verrucaeformis, and a fungus described herein as Cryptosporiopsis querciphila sp. nov. One-year-old coast Live Oak seedlings were wound inoculated under controlled conditions to test pathogenicity of the fungal species. Each fungal species was successfully reisolated from necrotic tissue at 70 and 100% for P. mortoniae and all other species, and xylem necrosis was significantly different between all treatments and controls (P < 0.0001 at α = 0.05). Isolates of F. solani were the most aggressive tested. These species represent new records of fungal pathogens of coast Live Oak in California. Results from the pathogenicity test suggest that these fungi play a role in the decline of southern California coast Live Oak trees. Oak woodlands support higher levels of biodiversity than any other terrestrial ecosystem in California (47). Coast Live Oak (Quercus agrifolia) is a common evergreen tree that dominates Oak woodlands throughout western North America, from Mendocino County, CA to Baja California, Mexico (40). In addition to providing important habitats for wildlife, coast Live Oak is frequently used throughout the United States for landscaping purposes (41). For these reasons, susceptibility of coast Live Oak to biotic factors that cause or contribute to tree mortality is a great concern.
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identification and pathogenicity of botryosphaeriaceae species associated with coast Live Oak quercus agrifolia decline in southern california
Mycologia, 2013Co-Authors: S C Lynch, Paul J Zambino, Joey S Mayorquin, Akif Eskalen, D H WangAbstract:Symptoms of decline have been observed on dying coast Live Oak (Quercus agrifolia) trees in areas throughout southern California that are both infested and uninfested by the gold-spotted Oak borer (GSOB). The purpose of this study was to identify and assess the pathogenicity of several anamorph species of the Botryosphaeriaceae, including Diplodia corticola, Dothiorella iberica and Diplodia agrifolia sp. nov., that were recovered consistently from symptomatic tissues. Species were identified morphologically and by phylogenetic analyses of the complete sequence of the internal transcribed spacer (ITS) of the rDNA and partial sequences of β-tubulin and elongation factor (EF1-α) genes. Results from morphological assessments and phylogenetic analyses support the erection of a new species closely related to D. mutila, described herein as Diplodia agrifolia sp. nov. Pathogenicity of all species was verified by wound inoculation of 1 y old coast Live Oak seedlings under controlled conditions. Isolates of D. corticola were the most aggressive tested, and isolates of D. agrifolia were the second most aggressive. Both species caused bleeding symptoms on inoculated seedlings. Seedlings inoculated with D. corticola died within 4 wk, with the pathogen progressing up and down through the xylem in advance of living phloem and moving throughout the taproot in 70% of inoculated seedlings. Colonization and re-isolation was successful for all species. All three fungal species represent newly recorded fungal pathogens of coast Live Oak in California. Results from the pathogenicity test suggest that these fungi play a role in the decline of coast Live Oaks throughout southern California.
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first report of bot canker caused by diplodia corticola on coast Live Oak quercus agrifolia in california
Plant Disease, 2010Co-Authors: S C Lynch, Paul J Zambino, Akif Eskalen, T ScottAbstract:Sharp decline and mortality of coast Live Oak (Quercus agrifolia) has been observed in San Diego County, CA since 2002. Much of this decline has been attributed to a new pest in California, the goldspotted Oak borer (GSOB, Agrilus coxalis) (1). Symptoms include crown thinning, bark cracking and/or peeling, patches of stain (1 to 10 cm in diameter), bleeding on the bole, and tree death and are most often observed on trees with a diameter at breast height (DBH) >30 cm. In 2008, a Botryosphaeria sp. was recovered from necrotic tissue of bleeding bole cankers from GSOB-affected trees in Jamul, CA. Zone lines separated dead and Live tissue in affected phloem and xylem. Pycnidia were observed on the bark surface of the infected host. Fifty conidia averaging 32 × 18 μm, one-septate with age, and morphologically similar to conidia described by Urbez-Torres et al. were observed (4). Oak stands with tree mortality were surveyed in GSOB-infested and -uninfested sites over eight locations throughout San Diego and Riv...
