Bacterial Leaf Scorch of Shade Trees.

Gould, Ann B.; Lashomb, James H.

doi:10.1094/apsnetfeature/2005-1105

Cited by 12 publications

(12 citation statements)

References 28 publications

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Section: Forest Speciesmentioning

confidence: 99%

“…In some New Jersey municipalities, leaf scorch was reported to affect up to 35% of oaks planted as street trees and in landscapes (Lashomb et al, 2002;Gould et al, 2004;Gould and Lashomb, 2005). Loss of value plus replacement costs for older trees affected by this disease was estimated at $8,000 per tree (Gould and Lashomb, 2005). An analysis of economic impact of X. fastidiosa indicated that the affected communities in New Jersey would sustain, and must plan for, losses ranging from $0.7 to 1.6 million during the following 10 years (Gould et al, 2004).…”

Section: Forest Speciesmentioning

confidence: 99%

“…Loss of value plus replacement costs for older trees affected by this disease was estimated at $8,000 per tree (Gould and Lashomb, 2005). An analysis of economic impact of X. fastidiosa indicated that the affected communities in New Jersey would sustain, and must plan for, losses ranging from $0.7 to 1.6 million during the following 10 years (Gould et al, 2004). In addition, it was noted that landowners and tree care professionals in these locations must plan for the loss of property values and high costs of replacement as shade trees in landscapes, wood lots, and golf courses affected by leaf scorch decline and must be removed (Gould and Lashomb, 2005).…”

Section: Forest Speciesmentioning

confidence: 99%

“…Although leaf scorch on elm is not deemed in itself lethal, it has been reported to predispose elms to attacks by elm bark beetles, which are vectors of the Dutch elm disease (DED) pathogen (Stipes and Campana, 1981). DED is the usual reason such trees die and are removed (Gould and Lashomb, 2005). DED in an elm population surveyed for several years in District of Columbia was about 12 times as common in scorch-affected elms as in others.…”

Section: Forest Speciesmentioning

confidence: 99%

See 3 more Smart Citations

Update of the Scientific Opinion on the risks to plant health posed by Xylella fastidiosa in the EU territory

Bragard¹,

Dehnen‐Schmutz²,

Serio³

et al. 2019

EFS2

140

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EFSA was asked to update the 2015 EFSA risk assessment on Xylella fastidiosa for the territory of the EU. In particular, EFSA was asked to focus on potential establishment, short-and long-range spread, the length of the asymptomatic period, the impact of X. fastidiosa and an update on risk reduction options. EFSA was asked to take into account the different subspecies and Sequence Types of X. fastidiosa. This was attempted throughout the scientific opinion but several issues with data availability meant that this could only be partially achieved. Models for risk of establishment showed most of the EU territory may be potentially suitable for X. fastidiosa although southern EU is most at risk. Differences in estimated areas of potential establishment were evident among X. fastidiosa subspecies, particularly X. fastidiosa subsp. multiplex which demonstrated areas of potential establishment further north in the EU. The model of establishment could be used to develop targeted surveys by Member States. The asymptomatic period of X. fastidiosa varied significantly for different host and pathogen subspecies combinations, for example from a median of approximately 1 month in ornamental plants and up to 10 months in olive, for pauca. This variable and long asymptomatic period is a considerable limitation to successful detection and control, particularly where surveillance is based on visual inspection. Modelling suggested that local eradication (e.g. within orchards) is possible, providing sampling intensity is sufficient for early detection and effective control measures are implemented swiftly (e.g. within 30 days). Modelling of long-range spread (e.g. regional scale) demonstrated the important role of long-range dispersal and the need to better understand this. Reducing buffer zone width in both containment and eradication scenarios increased the area infected. Intensive surveillance for early detection, and consequent plant removal, of new outbreaks is crucial for both successful eradication and containment at the regional scale, in addition to effective vector control. The assessment of impacts indicated that almond and Citrus spp. were at lower impact on yield compared to olive. Although the lowest impact was estimated for grapevine, and the highest for olive, this was based on several assumptions including that the assessment considered only Philaenus spumarius as a vector. If other xylem-feeding insects act as vectors the impact could be different. Since the Scientific Opinion published in 2015, there are still no risk reduction options that can remove the bacterium from the plant in open field conditions. Short-and long-range spread modelling showed that an early detection and rapid application of phytosanitary measures, consisting among others of plant removal and vector control, are essential to prevent further spread of the pathogen to new areas. Further data collection will allow a reduction in uncertainty and facilitate more tailored and effective control given the intraspecific diversity of X. fastidiosa an...

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Section: Forest Speciesmentioning

confidence: 99%

Section: Forest Speciesmentioning

confidence: 99%

Section: Forest Speciesmentioning

confidence: 99%

Section: Forest Speciesmentioning

confidence: 99%

See 2 more Smart Citations

Update of the Scientific Opinion on the risks to plant health posed by Xylella fastidiosa in the EU territory

Bragard¹,

Dehnen‐Schmutz²,

Serio³

et al. 2019

EFS2

140

View full text Add to dashboard Cite

show abstract

“…Many electron micrographs of petiole xylem from various shade tree hosts have shown large cell masses loaded into single vessels while surrounding vessels are free of bacteria ( Hearon et al , 1980 ; see Fig. 6 within their publication; Gould and Lashomb, 2005 ; image of Pin oak by JR Hartman). The bacteria in these images are often loaded into pit chambers and pressed against the pit membrane, but only on the side of the mass colonized vessel.…”

Section: Discussionmentioning

confidence: 99%

Hydraulic disruption and passive migration by a bacterial pathogen in oak tree xylem

McElrone

Jackson

Habdas

2008

Journal of Experimental Botany

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Xylella fastidiosa (Xf) is a xylem-limited bacterial pathogen that causes leaf scorch symptoms in numerous plant species in urban, agricultural, and natural ecosystems worldwide. The exact mechanism of hydraulic disruption and systemic colonization of xylem by Xf remains elusive across all host plants. To understand both processes better, the functional and structural characteristics of xylem in different organs of both healthy and Xf-infected trees of several Quercus species were studied. Hydraulic conductivity (Ks) in Xf-infected petioles of Q. palustris and Q. rubra decreased significantly compared with healthy trees as the season progressed and plummeted to zero with the onset of scorch symptoms. Prior to the onset of symptoms, embolism was as much as 3.7 times higher in Xf-infected petioles compared with healthy controls and preceded significant reductions in Ks. Embolism likely resulted from pit membrane degradation during colonization of new petiole xylem and triggered the process that eventually led to vessel occlusion. Pit membrane porosity was studied using the following four methods to determine if a pathway exists in the xylem network of woody stems that allows for passive Xf migration: (i) calculations based on vulnerability to cavitation data, (ii) scanning electron micrographs, (iii) microsphere injections, and (iv) air seeding thresholds on individual vessels. All four methods consistently demonstrated that large pit membrane pores (i.e. greater than the diameter of individual Xf) occur frequently throughout the secondary stem xylem in several Quercus species. These large pores probably facilitate systemic colonization of the secondary xylem network and contribute to the high susceptibility to bacterial leaf scorch exhibited among these species.

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Host Specificity of Pecan Strains ofXylella fastidiosasubsp.multiplex

Sanderlin

2017

Plant Disease

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Pecan (Carya illinoinensis) bacterial leaf scorch disease, caused by Xylella fastidiosa subsp. multiplex, causes defoliation and reduces terminal growth and nut yield. The pathogen is transmitted to pecan by xylem-feeding spittlebugs and leafhoppers and through graft transmission in the clonal propagation of cultivars. Xylella fastidiosa subsp. multiplex has a broad host range, infecting numerous hardwood tree species and some herbaceous species. There is evidence of additional host specialization within subsp. multiplex. Data presented here support the existence of host specialization with X. fastidiosa that infect pecan. In this study, mechanical inoculation was used to inoculate several plant species that are naturally infected by subsp. multiplex, including sycamore, red maple, purple-leafed plum, and blueberry with strains of X. fastidiosa from pecan. Hosts of three other subspecies were also inoculated with the pecan strains: grapevine (subsp. fastidiosa); oleander (subsp. sandyi); and mulberry (subsp. morus). Pecan was also inoculated with a strain of the pathogen from sycamore (subsp. multiplex) and a strain from grapevine (subsp. fastidiosa). In greenhouse tests, inoculum prepared from X. fastidiosa obtained from naturally infected pecan almost exclusively infected pecan. In addition, the subsp. multiplex strain from sycamore generally did not infect pecan, and the subsp. fastidiosa strain from grapevine did not infect pecan. The inability of the pecan strain to readily infect other hosts commonly located in the vicinity of pecan orchards affects the management recommendations for the disease in commercial pecan production by allowing management practices to focus on pecan orchards and insect vectors.

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Bacterial Leaf Scorch of Shade Trees.

Cited by 12 publications

References 28 publications

Update of the Scientific Opinion on the risks to plant health posed by Xylella fastidiosa in the EU territory

Update of the Scientific Opinion on the risks to plant health posed by Xylella fastidiosa in the EU territory

Hydraulic disruption and passive migration by a bacterial pathogen in oak tree xylem

Host Specificity of Pecan Strains ofXylella fastidiosasubsp.multiplex

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