Progress 01/01/07 to 12/31/07

Outputs
OUTPUTS: Bacterial leaf scorch of amenity trees (BLS) is widespread throughout the eastern US, affecting 20 to 48% of oaks in the red oak group in some New Jersey municipalities. In this project we are investigating mechanisms of disease development and vector transmission to identify non-invasive disease management options for community arborists. Results include: 1) In 2007, the characterization of insects that may serve as potential vectors for Xylella 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. 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. 2) Disease progression: a ground survey for BLS begun in 2003 was completed at a final location; disease incidence was appx. 14%. 3) 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. 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.

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 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. Further analysis of bacterial isolates may help to reveal the source of the New Jersey isolates and help to track movement of the bacterium between alternate host vegetation, vector, and oak host.

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.

Progress 10/01/01 to 09/30/07

Outputs
OUTPUTS: Bacterial leaf scorch of amenity trees (BLS) is widespread throughout the eastern US, affecting 20 to 48% of oaks in the red oak group in some New Jersey municipalities. In this project we are investigating mechanisms of disease development and vector transmission to identify non-invasive disease management options for community arborists. Results include: 1) In 2007, the characterization of insects that may serve as potential vectors for Xylella 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. 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. 2) Disease progression: a ground survey for BLS begun in 2003 was completed at a final location; disease incidence was appx. 14%. 3) 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. 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.

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 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. Further analysis of bacterial isolates may help to reveal the source of the New Jersey isolates and help to track movement of the bacterium between alternate host vegetation, vector, and oak host.

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.

Progress 01/01/05 to 12/31/05

Outputs
Bacterial leaf scorch of amenity trees (BLS) is widespread throughout the eastern US and affects as many as 44% of oaks in the red oak group in some New Jersey municipalities. In this project we hope to investigate mechanisms of disease development and vector transmission to identify non-invasive disease management options for community arborists. Results include: 1) Vector transmission: Xylem feeder population dynamics have been monitored using refined techniques at four research locations. Of 2000+ insects collected, 34 species leafhoppers and 13 species of treehoppers have been identified. Populations of xylem feeders at each site is seasonally influenced; the number of insects collected was greatest in early summer for treehoppers and mid- to late summer for leafhoppers. In addition, populations of xylem feeders tend to be significantly greater in asymptomatic oaks. 2) Disease progression: Ground surveys for BLS begun in 2002 were continued at four locations. The incidence of BLS in a Monmouth County community varied from 38 to 44%. Although disease incidence in a Middlesex and Mercer County locations was lower, BLS still affected a sizeable portion of the oak street tree resource. In most surveys, average crown dieback of symptomatic oaks was between 15 and 30%. With the exception of one sweetgum, all other shade trees species examined during the survey appeared to be free of the disease. 3). Characterization of strains: 18 isolates of Xylella fastidiosa from red and pin oaks symptomatic for BLS were obtained. The isolates were confirmed 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. 4. Alternative hosts: At four sites, all plant species within a 100-m radius of several oaks symptomatic for BLS were identified, and representative samples were subject to ELISA for the presence of X. fastidiosa. To improve detection of the pathogen in asymptomatic hosts, an optical density index of 2.0 for the ELISA procedure was statistically calculated; plants with an index above this threshold were considered positive. Using these criteria, 46 species in 31 families were confirmed as hosts for X. fastidiosa. 5. Differences in xylem fluid chemistry between symptomatic and asymptomatic oaks: In 2005, a study was initiated to examine xylem water pressure and xylem nutritional profiles among oak species. Xylem fluid was obtained from symptomatic red and pin oaks as well as asymptomatic red, pin, and white oaks using a pressure chamber modified for use on small plant branches. A negative relationship was evident between water pressure and the degree of infection, indicating that the xylem vessels of infected plants are sufficiently compromised to impact water movement through the tree. Water pressure, however, differs little among healthy trees, regardless of species.

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 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. Further analysis of bacterial isolates may help to reveal the source of the New Jersey isolates and help to track movement of the bacterium between alternate host vegetation, vector, and oak host.

Publications

• Gould, A. B., Zhang, J., Staniszewska-Goraczniak, H., Hamilton, G., Hillman, B., Goraczniak, R., and Lashomb, J. 2005. Preliminary characterization of Xylella fastidiosa strains isolated from oak in New Jersey. Phytopathology 95:S36.
• Gould, A. B., and Lashomb, J. 2005. Bacterial leaf scorch of shade trees. APSnet Feature Article. APS Press. http://www.apsnet.org/online/feature/bls/

Progress 01/01/04 to 12/31/04

Outputs
We reported that 420 trees in Union and Middlesex Counties, New Jersey, tested positive for Asian longhorned beetle. Eradication efforts are underway. We've established that as many as 35% of red and pin oaks in some New Jersey towns are infected with the bacterial leaf scorch (BLS) pathogen, Xylella fastidiosa. An ongoing research project aims at indentifying insect vectors of BLS in New Jersey, tracking progress of the disease in several NJ communities, estimating the economic costs of the disease to these communities, and devising cost-effective remedial practices. PCR is being used to detect the BLS pathogen in captured insects that are potential vectors.

Impacts
Research from this study will provide information on which tools are most effective in managing plant diseases and pests

Publications

• No publications reported this period

Progress 01/01/03 to 12/31/03

Outputs
The NJ participants joined in early 2004. It is too early to report on their activities.

Impacts
The NJ participants joined in early 2004. It is too early to report on their activities.

Publications

• No publications reported this period