Progress 10/01/05 to 09/30/09
Outputs
OUTPUTS: During the 2009 field season, we focused on the final data year for a 3-year study (including a 2-year survey) of BLS in 26 northeast, mid-Atlantic, mid-western, and plains states. This work was co-sponsored by the US Forest Service, Michigan State University, and Rutgers University. The objective of this work was to determine the distribution of the disease in these areas, identify new hosts, and relate the occurrence of BLS to mapped landscape-scale physiographic, edaphic, and climatic data. Samples of hardwoods with leaf scorch, collected by University and Forest Service personnel, were tested for Xylella using ELISA and real-time PCR protocols. We continued to refine the sampling protocol for the use of real-time PCR in plant and insect samples. Sample collection for year 2 of this project is complete. Approximately 300 branch samples were received for analysis, and all samples from the northeast have been tested using the ELISA and real-time PCR protocols. There is a strong relationship between ELISA and real-time PCR results. The PCR protocol is more sensitive. We expect to complete this phase of the project by March 1, 2010, at which time we will map our findings and explore relationships between disease incidence and climatic, physiographic, and edaphic data. Many species already identified as hosts of BLS, such as some maples and oaks, tested positive for the bacterium. New finds include witch hazel and blueberry. The pathogen was detected in most of the northeastern states sampled (CT, DC, DE, MD, ME, NH, NJ, NY, PA, RI, VT, and WV) as well as several mid-western states (IL, IN, KS, MO, WI, and OK). PARTICIPANTS: Co Investigators: James Lashomb, George Hamilton, Mark Vodak, Jason Grabosky. Plant disease diagnotician: Richard Buckley. Technician: Melinda Moy. TARGET AUDIENCES: This research is in direct response to requests for management strategies for BLS from stakeholder groups, which include the New Jersey Bureau of Forestry, the Monmouth County Shade Tree Commission, the New Jersey Shade Tree Federation, the Community Forestry Council, the New Jersey Nursery and Landscape Association, and the U.S. Forest Service. Other groups with interest in this research include county shade tree commissions, municipal arborists, community foresters, golf course superintendents, and landscape professionals. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
The biology and spread of BLS, caused by the bacterium Xylella fastidiosa, is complex and is determined in large part by the species of insects that vector the bacterium, bacterial strain, species/genetics of the host tree, and alternative hosts (plants that harbor the bacterium and may serve as a reservoir for disease). Without a clear understanding of the disease, however, it is difficult to devise preventive or remedial strategies that community arborists can use to delay or manage the epidemic. As part of on-going surveys for the disease in several communities, it was determined that the total value for trees with BLS was $2.4 million for two communities combined. We estimate that many of these trees will be removed within the next 10-year period, thus these communities must plan for these losses in the near future.
Publications
- No publications reported this period
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Progress 01/01/08 to 12/31/08
Outputs
OUTPUTS: BLS incidence: During the 2008 field season, we focused on a 2-year survey of BLS in 26 northeast, mid-Atlantic, mid-western, and plains states. This work was co-sponsored by the US Forest Service, Michigan State University, and Rutgers University. The objective of this work was to determine the distribution of the disease in these areas, identify new hosts, and relate the occurrence of BLS to mapped landscape-scale physiographic, edaphic, and climatic data. Samples of hardwoods with leaf scorch, collected by University and Forest Service personnel, were tested for Xylella using ELISA and real-time PCR protocols. The real-time PCR assay has been refined for use in plant and insect samples during the past year. Sample collection for year 1 of this project is complete. More than 600 branch samples were received for analysis, and all samples from the northeast have been tested using the ELISA and/or real-time PCR protocols. We expect to complete this phase of the project by March 1, 2009 , at which time we will map our findings and explore relationships between disease incidence and climatic, physiographic, and edaphic data. Many species already identified as hosts of BLS, such as some maples and oaks, tested positive for the bacterium. New finds include witch hazel as well as an unidentified species of chestnut. Samples of dogwood, laurel, and blueberry were not positive for the pathogen. In vector studies: Insects that feed on xylem fluid (such as cicadas, leafhoppers, treehoppers, and spittlebugs) are potential vectors for Xylella fastidiosa. Previous reports include surveys of insect abundance in populations of susceptible oaks, as well as an assessment of the percentage of insects testing positive for Xylella. Of note, a relatively high percentage of xylem feeding insects of varying species tested positive for the pathogen (15.4% of 1100 insect specimens assayed; 19 of 35 insect species collected). Infectivity rates of the two most abundant insects, Ophiderma definita (a treehopper) and Graphocephala versuta (a leafhopper), were 15 and 21%, respectively. Using molecular methods, we found that certain portions of bacterial DNA from strains isolated from these insects are identical to those isolated from oak hosts in New Jersey. It now becomes critical to understand the role these "presumptive vectors" play in the disease cycle of BLS within populations of susceptible trees. Treehoppers, not previously associated with BLS, remain in the oak canopy throughout their life cycle and may play an important role in within-tree spread of the bacterium. Leafhoppers, which must move from host to host to acquire different levels of nutrients at each life stage, are likely agents of between-species spread. The working group at Rutgers is currently focused on the development and distribution of a pictorial key of xylem feeding insects for use by arborists as part of an "early warning system" needed to identify the risk of BLS within populations of susceptible trees. PARTICIPANTS: Individuals: Gould, Ann B. Co-PI. Assoc. Extension Specialist in Plant Pathology, Department of Plant Biology and Pathology, Rutgers University. Co-PI. Lashomb, James. Co-PI. Extension Specialist in Entomology, Department of Entomology, Rutgers University. Co-PI. Zhang, Jianxin. Graduate Assistant and Technician. Department of Entomology, Rutgers University. Halina Staniszewska. Technician. Department of Plant Biology and Pathology, Rutgers University. Melinda Moy. Technician. Department of Plant Biology and Pathology, Rutgers University. Partners: US Forest Service PennDel Chapter International Society of Arboriculture Michigan State University Training Maimone, Lisa. Undergraduate student. Rutgers University. TARGET AUDIENCES: Traget audiences include commercial and community arborists and tree care professionals, landscape professionals, golf course superintendents. Efforts included extension presentations and newsletter articles. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
The biology and spread of BLS, caused by the bacterium Xylella fastidiosa, is complex and is determined in large part by the species of insects that vector the bacterium, bacterial strain, species/genetics of the host tree, and alternative hosts (plants that harbor the bacterium and may serve as a reservoir for disease). Without a clear understanding of the disease, however, it is difficult to devise preventive or remedial strategies that community arborists can use to delay or manage the epidemic. As part of on-going surveys for the disease in several communities, it was determined that the total value for trees with BLS was $2.4 million for two communities combined. We estimate that many of these trees will be removed within the next 10-year period, thus these communities must plan for these losses in the near future.
Publications
- Zhang, J. 2008. Bacterial leaf scorch: Xylella fastidiosa Wells et al. and its potential insect vectors in pin and red oaks in New Jersey. Ph.D. Dissertation, Graduate School New Brunswick, Rutgers University, October, 2008.
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Progress 01/01/07 to 12/31/07
Outputs
OUTPUTS: In 2007, yearly monitoring of susceptible oak populations in the New Jersey community of East Windsor was continued to assess the spread of bacterial leaf scorch of oak (caused by Xylella fastidiosa) within street tree populations over time. In August to October 2007, all street-side oak trees in East Windsor were evaluated for the presence and severity of BLS. Disease incidence was approximately 14%. Also in 2007, the characterization of insects that may serve as potential vectors for X. fastidiosa continued. In this study, 39 potential vector species were collected from 19 genera in five families, including leafhoppers and treehoppers. The fogging method collected many more insect species and individuals, which can be used as a relatively accurate estimate of population abundance at a given point in time. Non-destructive sticky card sampling at a greater frequency and a larger number of locations provided similar community structure information as that from fogging, but
sampling efficiency varied with insect behavior and distribution in oak canopy. Seasonal population dynamics were described for the major insect species. Each of the two most dominant Cicadomorpha insect species had a single major peak in June, for Ophiderma definita (treehopper), and in July, for Graphocephala versuta (leafhopper). Insect population varied with years and oak species. O. definita was more abundant in pin oaks than red oaks. A DNA extraction procedure developed in 2006 was used to continue the assessment of X. fastidiosa in potential insect vectors. Approximately 1100 insect specimens collected by fogging were subject to a PCR procedure. Based on this method, 20 of 35 insect species tested positive for the pathogen. The average positive rate was 15.4% of the entire insect community tested, and the bacterium presented in the vector population throughout the summer. Within the individual insect groups, 12% of treehoppers, 21% of leafhoppers, and 15% of spittlebugs were
positive for the bacterium. Finally, real-time (QRT) PCR was adapted to determine when bacterial cells can be first detected in asymptomatic oak tissue during the growing season. Four oak trees (2 red and 2 pin) with a history of BLS were sampled on five dates (May to July) throughout the summer. DNA was extracted from petiole tissue and was amplified using QRT-PCR. Plant material was also plated on a standard medium used for X. fastidiosa to double-check results. For all samples, levels of pathogen DNA were not detected until the July 5 sampling. Our preliminary work shows that QRT-PCR will become a useful tool in the identification and diagnosis process for BLS.
PARTICIPANTS: Participants: AB Gould, JH Lashomb, J Zhang, Q Huang, H Staniszewska-Goraczniak, R Goraczniak, K Kjer, R Obal, M Vodak, J Grabosky, L Schlitt, R Orr. Contacts: International Society of Arboriculture PennDel Chapter, ISA Tree Fund, Duke Gardens, New Jersey Shade Tree Federation, Mercer Community College.
TARGET AUDIENCES: Target audiences: community arborists, state foresters, park managers, landscape professionals.
Impacts
The biology and spread of BLS, caused by the bacterium Xylella fastidiosa, is complex and is determined in large part by the species of insects that vector the bacterium, bacterial strain, species/genetics of the host tree, and alternative hosts (plants that harbor the bacterium and may serve as a reservoir for disease). Without a clear understanding of the disease, however, it is difficult to devise preventive or remedial strategies that community arborists can use to delay or manage the epidemic. As part of on-going surveys for the disease in several communities, it was determined that the total value for trees with BLS was $2.4 million for two communities combined. We estimate that many of these trees will be removed within the next 10-year period, thus these communities must plan for these losses in the near future.
Publications
- Zhang J, Gould AB, Lashomb JH, Huang Q, Staniszewska-Goraczniak H, Goraczniak R, Kjer K. 2007. Characterization of Xylella fastidiosa strain isolated from oak and insect vectors in New Jersey: 16S-23S ribosomal RNA intergenic spacer, partial sequences; 4 sequences from 19 isolates. NCBI CoreNucleotide Sequences. Accession numbers EU334012 to EU334087. http://www.ncbi.nlm.nih.gov/sites/entrez
- Gould AB, Lashomb J. 2007. Plant Disease Lesson: Bacterial leaf scorch of Shade Trees. The Plant Health Instructor. DOI: 10.1094/PHI-I-2007-0403-07.
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Progress 01/01/06 to 12/31/06
Outputs
In 2006, yearly monitoring of oak populations in several New Jersey communities was continued to assess the spread of bacterial leaf scorch of oak (caused by Xylella fastidiosa) within street tree populations over time. In August to October 2006, all street-side oak trees in Allentown, Cranbury, and East Windsor, NJ were evaluated for the presence and severity of BLS. Disease incidence was 14, 38, and 31% for East Windsor, Cranbury, and Allentown, respectively. Also in 2006, xylem-feeding insects (potential vectors of X. fastidiosa) were collected from the canopies of red (Quercus rubra) and pin (Q. palustris) oak trees at four New Jersey locations (Duke Farms, Somerville; Mercer County Community College, West Windsor; Riverview Cemetery, Trenton; and Rutgers University, New Brunswick). To collect seasonal data, sticky traps were placed in the canopies of symptomatic or asymptomatic oaks at each site, and these were monitored weekly from May to August. To assess
population abundance, selected trees at each location were fogged once a month with pyrethrin insecticide. Ten thousand xylem-feeding insects were collected, and a seasonal profile of the major species was compiled. Regardless of collection method, membracids (treehoppers) comprised the highest percent of total xylem-feeding insects (95% in fogged trees; 83% in canopies with sticky cards). These insects were most abundant early in the growing season; populations of cicadellids (leafhoppers) were lower throughout the collection period and peaked in July. A DNA extraction procedure developed in 2005 to detect X. fastidiosa in potential insect vectors was refined in 2006. Insect specimens collected by fogging were dissected to remove eyes, wings, legs, and the terminal abdomen to increase DNA extraction efficiency. Insects were subject to a PCR procedure, also developed in 2005, using primer RST31/33. Based on this method, nine insect species out of 24 tested were positive for X.
fastidiosa; within a sample size of 1070 individuals tested, 14.4% were positive for the pathogen. Of the 422 Graphocephala versuta (leafhopper) individuals tested, 20% were positive for X. fastidiosa, representing the highest rate of infectivity for all species evaluated.
Impacts
In spite of the widespread distribution of BLS in New Jersey, very little is known of the biology of the disease, its progression, and effective management. More information regarding the pattern of new infections, the seasonal cycles of insect vectors, and the role of alternative, "potential-reservoir" hosts on disease development is needed before effective management strategies can be devised. As part of on-going surveys for the disease in several communities, it was determined that the total value for trees with BLS was $2.4 million for two communities combined. We estimate that many of these trees will be removed within the next 10-year period, thus these communities must plan for these losses in the near future.
Publications
- Gould, A. B., Hamilton, G., Vodak, M., Grabosky, J., and Lashomb, J. 2006. Economic impact of bacterial leaf scorch in the New Jersey urban forest. Entomological Society of America annual meeting, Indianapolis, IN.
- Zhang, J., Lashomb, J., Gould, A. B., and Hamilton, G. 2006. Xylophages inhabiting red and pin oak in New Jersey. Entomological Society of America annual meeting, Indianapolis, IN.
- Gould, A. B., Hamilton, G., Vodak, M., Grabosky, J., Staniszewska, H., and Lashomb J. 2006. Incidence and Severity of Bacterial Leaf Scorch in New Jersey. Northeastern Division APS meeting, Burlington, VT. Abstract for Phytopathology (abstract in press).
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Progress 01/01/05 to 12/31/05
Outputs
In 2005, yearly monitoring of oak populations in several New Jersey communities was continued to assess the spread of bacterial leaf scorch of oak (caused by Xylella fastidiosa) within street tree populations over time. In August to October 2005, all street-side oak trees in Allentown, Cranbury, and East Windsor, NJ were evaluated for the presence and severity of BLS. Disease incidence was 24, 28, and 39% for East Windsor, Cranbury, and Allentown, respectively. As part of the survey, 18 bacterial isolates obtained from red (11 isolates) and pin (7 isolates) oaks symptomatic for BLS were confirmed to be X. fastidiosa using ELISA as well as PCR with primers specific to this pathogen. All New Jersey strains, regardless of host origin or location, were identical in nucleotide sequence and shared greater than 95% nucleotide sequence identity with X. fastidiosa strains isolated from other hosts. A phylogenetic tree using primer sequences revealed a monophyletic clade with
porcelain berry from Virginia and oaks from New Jersey, Florida, and Georgia. A DNA extraction procedure was also developed to detect X. fastidiosa in potential insect vectors. Insect specimens collected in 2004 and stored at -20oC were dissected to remove eyes, wings, legs, and the terminal abdomen to increase DNA extraction efficiency. A new PCR procedure was developed for more sensitive detection of X. fastidiosa using primer RST31/33. Based on this method, six species out of nine tested were positive for X. fastidiosa; within a sample size of 46 individuals tested, 34.8% were positive for the pathogen.
Impacts
In spite of the widespread distribution of Bacterial Leaf Scorch in New Jersey, very little is known of the biology of the disease, its progression, and effective management. More information regarding the pattern of new infections, the seasonal cycles of insect vectors, and the role of alternative, "potential-reservoir" hosts on disease development is needed before effective management strategies can be devised. As part of on-going surveys for the disease in several communities, it was determined that including costs for removal and stump grinding ($2000), total value for trees with BLS were $2.4 million for two communities combined. We estimate that many of these trees will be removed within the next 10-year period, thus these communities must plan for these losses in the near future.
Publications
- Gould, A. B., and Lashomb, J. 2005. Bacterial Leaf Scorch of Shade Trees. APSnet Feature Article (invited). APS Press. http://www.apsnet.org/online/feature/bls/
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Progress 01/01/04 to 12/31/04
Outputs
In 2004, weekly monitoring of xylem-feeding insects in oak (potential vectors of bacterial leaf scorch, or BLS) using fogging or sticky traps continued in symptomatic or asymptomatic oaks at four sites (Rutgers Gardens, North Brunswick, NJ; Duke Farms, Somerville, NJ; Mercer County Community College, East Windsor, NJ; and Riverview Cemetery, Trenton, NJ). Vector population seasonal dynamics were described for each species at each site based on oak species, trap orientation, trap height, tree infection intensity (low and high), and plant community structure. Results from fogging experiments indicate that there were more insects in healthy oaks compared to symptomatic trees. In August, alternative host sampling was conducted in the vicinity of major BLS sites. 207 plants within a 100-m radius of highly symptomatic trees were sampled and tested for Xylella fastidiosa using ELISA. Postive samples were stored for re-testing with PCR to further characterize the potential
host range of this pathogen. Finally, to assess the spread of BLS within populations of oaks over time, yearly monitoring of oak populations in several New Jersey communities was continued. In August to October 2004, all street-side oak trees in Allentown, Cranbury, and East Windsor, NJ were evaluated for the presence and severity of BLS. Disease incidence was 21, 28, and 44% for East Windsor, Cranbury, and Allentown, respectively. To assess economic impact of this disease in these localities, the Trunk formula method was used to estimate the average tree value of diseased trees. Including costs for removal and stump grinding ($2000), total value for trees with BLS were $629,000 and $1,775,000 for Allentown and Cranbury, respectively. Disease incidence maps were generated using GPS coordinates, and an autocorrelation analysis was performed to detect spatial relationships among trees. For Allentown, the condition of trees within 20-25 m was correlated, thus diseased trees were
clustered in the landscape. Using GPS-GIS technology, we hope to determine whether geographic features as well as other underlying features (e.g., soil type, hydrology, water table, topography) may be associated with disease predisposition and vector movement.
Impacts
In spite of the widespread distribution of BLS in New Jersey, very little is known of the biology of the disease, its progression, and effective management. Methods for monitoring potential insect vectors in the canopy are primitive, and little is known regarding the transmission rate and spread of this disease both within and between trees. More information regarding the pattern of new infections, the seasonal cycles of insect vectors, and the role of alternative, "potential-reservoir" hosts on disease development is needed before effective management strategies can be devised. If uninvestigated and untreated, BLS will continue to debilitate municipalities where widespread overplanting of red and pin oaks has occurred.
Publications
- Bacterial leaf scorch of oak in New Jersey: Incidence and economic impact. 2004. A. B. GOULD, G. Hamilton, M. Vodak, J. Grabosky, and J. Lashomb. Rutgers University, New Brunswick, NJ. Phytopathology 94:S36.
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Progress 01/01/03 to 12/31/03
Outputs
In 2003, xylem-feeding insects in oak (potential vectors of Bacterial leaf scorch) were collected using sticky traps in tree canopies and insecticide fogging. Traps were placed in 63 symptomatic or asymptomatic oaks in the Rutgers Gardens, North Brunswick, NJ Duke Farms, Somerville, NJ, and Riverview Cemetery, Trenton, NJ and were monitored weekly from May to August. Several thousand xylem-feeding insects were collected and a seasonal profile of the major species was compiled. Insects most commonly collected included the membracids (treehoppers) Ophiderma, Telamona, and Archasia, and the cicadellids (leafhoppers) Graphocephala, Oncometopia, Paraphlepsius, Erythroneura, and Empoasca. Other xylem-feeding insects collected included one species of cicada and froghopper and several planthopper species. In another aspect of this study, potential alternative host vegetation in the vicinity of diseased trees was screened for Xylella fastidiosa using ELISA. In September, 250
different weed, tree, and shrub species were sampled in two heavily infested communities in Middlesex and Mercer counties, NJ. Finally, to assess the spread of BLS within populations of oaks over time, long-term, yearly monitoring of oak populations in several New Jersey communities that began in 2002 will continue through 2005. In September 2003, all street-side oak trees in East Windsor, NJ and a relatively recent development outside Cranbury, NJ were georeferenced, measured (diameter of tree breast-height), and evaluated for the presence and severity of BLS. In addition, on-going monitoring of BLS in street-side oaks in Cranbury and Allentown, NJ continued. Percent street-trees with BLS ranged from 6% (East Windsor) to 38% (Allentown). Using this data, incidence maps for each location are being generated.
Impacts
In spite of the widespread distribution of BLS in New Jersey, very little is known of the biology of the disease, its progression, and effective management. Methods for monitoring potential insect vectors in the canopy are primitive, and little is known regarding the transmission rate and spread of this disease both within and between trees. More information regarding the pattern of new infections, the seasonal cycles of insect vectors, and the role of alternative, "potential-reservoir" hosts on disease development is needed before effective management strategies can be devised. If uninvestigated and untreated, BLS will continue to debilitate municipalities where widespread overplanting of red and pin oaks has occurred.
Publications
- No publications reported this period
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Progress 01/01/02 to 12/31/02
Outputs
In 2002, sampling techniques for the vectors of Bacterial leaf scorch (BLS) were developed and refined. Placement of sticky traps in tree canopies and other devices to dislodge insects (e.g., the use of sweeps and insecticide fogging) were used to collect xylem-feeding insects from oak. Traps, placed in symptomatic and asymptomatic oaks in the Rutgers Gardens, North Brunswick, NJ and in asymptomatic trees at Duke Farms, Somerville, NJ, were monitored weekly between June and August. Several thousand insects were collected, and vectors of Xylella fastidiosa known to be associated with other diseases were identified. A seasonal profile of the major species has been produced from the data, and a species list with photographs has been compiled. In another aspect of this study, potential alternative host vegetation in the vicinity of diseased trees was screened for X. fastidiosa using ELISA. In September, 230 different weed, tree, and shrub species were sampled in two
heavily infested communities in Middlesex and Mercer counties, NJ. Species that tested posted for X. fastidiosa included yarrow, annual ragweed, dodder, California privet, American pokeweed, and green foxtail. Finally, to assess the spread of BLS within populations of oaks over time, long-term, yearly monitoring of oak populations in several New Jersey communities that began in 2002 will continue through 2005. In September, all street-side oak trees in Cranbury and Allentown, NJ were georeferenced, measured (diameter of tree breast-height), and evaluated for the presence and severity of BLS. In each community 27 to 29% of oaks were positive for BLS. In addition, oak trees on Cook Campus, Rutgers University, were evaluated (data analysis not complete). Using this data, incidence maps for each location are being generated.
Impacts
In spite of the widespread distribution of BLS in New Jersey, very little is known of the biology of the disease, its progression, and effective management. Methods for monitoring potential insect vectors in the canopy are primitive, and little is known regarding the transmission rate and spread of this disease both within and between trees. More information regarding the pattern of new infections, the seasonal cycles of insect vectors, and the role of alternative, "potential-reservoir" hosts on disease development is needed before effective management strategies can be devised. If uninvestigated and untreated, BLS will continue to debilitate municipalities where widespread overplanting of red and pin oaks has occurred.
Publications
- Lashomb, J., Iskra, A., Gould, A., and Hamilton, G., eds. 2002. Bacterial leaf scorch of amenity trees: a wide-spread problem of economic significance to the urban forest. USDA Forest Service, Forest Health Protection, Morgantown, WV, NA-TP-01-03.
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