First Report of Bacterial Leaf Scorch Disease of American Elm Caused by Xylella fastidiosa in Georgia, U.S.A.

Bacterial leaf scorch caused by Xylella fastidiosa has been reported in 17 species of oak including bur, pin, red, scarlet, shingle, and white oaks (3). In September 2002, a leaf scorch symptom characterized by marginal necrosis of leaves bordered by a darker brown band was observed in a mature black oak (Quercus velutina Lam.) at the U.S. National Arboretum in Washington, D.C. The leaf petiole of the black oak was processed in general extraction buffer (Agdia, Inc., Elkhart, IN) contained in a FastDNA lysing matrix tube using the FastPrep FP120 instrument (Qbiogene, Inc., Carlsbad, CA) (1). The leaf petiole extract reacted with an antiserum specific for X. fastidiosa (Agadia, Inc.) in an enzyme-linked immunosorbent assay (ELISA). A slow-growing bacterium was cultured from leaf petioles of the affected black oak tree by soaking the surface-sterilized, finely cut leaf petioles in sterile water for 30 min, followed by spreading the bacterial suspension on periwinkle wilt plates (1). When the cultured bacterium was subjected to polymerase chain reaction (PCR) with primers specific for X. fastidiosa (2), a 472-bp PCR product was detected. The PCR product was confirmed to be the predicted X. fastidiosa product by sequencing and sequence comparison with the reported genomic sequence of X. fastidiosa. ELISA and bacterial isolation from leaf petioles of a nearby symptomless white oak (Q. alba L.) tree were negative. To our knowledge, this is the first report of X. fastidiosa associated with leaf scorch in black oak in the United States, expanding the host range of the bacterium in economically important landscape tree species. References: (1) Q. Huang and J. L. Sherald. Curr. Microbiol. 48:73, 2004. (2) M. R. Pooler and J. S. Hartung. Curr. Microbiol. 31:377, 1995. (3) J. L. Sherald. Xylella fastidiosa, A bacterial pathogen of landscape trees. Page 191 in: Shade Tree Wilt Diseases, C. L. Ash, ed. The American Phytopathological Society, 2001.

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Pecan Bacterial Leaf Scorch, Caused by Xylella fastidiosa, Is Endemic in Georgia Pecan Orchards

Plant Health Progress ◽

10.1094/php-08-18-0045-s ◽

2018 ◽

Vol 19 (4) ◽

pp. 284-287 ◽

Cited By ~ 1

Author(s):

Clive H. Bock ◽

Jonathan E. Oliver ◽

Chunxian Chen ◽

Michael H. Hotchkiss ◽

Katherine L. Stevenson ◽

...

Keyword(s):

Yield Loss ◽

Xylella Fastidiosa ◽

Severe Disease ◽

The United States ◽

Susceptible Cultivar ◽

Leaf Scorch ◽

Central Production ◽

Cape Fear ◽

Production Areas ◽

Bacterial Leaf Scorch

Pecan bacterial leaf scorch (PBLS), caused by Xylella fastidiosa, can cause severe disease in some pecan cultivars, resulting in yield loss. Only recently has some information been obtained regarding the distribution and extent of the disease in pecan in any state in the United States. With emphasis on a susceptible cultivar, Cape Fear, we sampled a total of 91 trees in eight orchards from the southwestern and central production areas in Georgia (GA) and found 60.4% of trees sampled infected, most showing symptoms of PBLS. Further multilocus sequence typing from 16 of these trees confirmed presence X. fastidiosa. The results confirm that X. fastidiosa is widespread geographically in GA, and different cultivars may be infected. This is the first definitive report confirming X. fastidiosa causing PBLS in different pecan producing areas and cultivars in GA.

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First Report of Bacterial Leaf Scorch Caused byXylella fastidiosaon Sugar Maple and Sweetgum

Plant Disease ◽

10.1094/pd-80-1302b ◽

1996 ◽

Vol 80 ◽

pp. 1302 ◽

Cited By ~ 7

Author(s):

J. R. Hartman

Keyword(s):

Sugar Maple ◽

First Report ◽

Leaf Scorch ◽

Bacterial Leaf Scorch

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Evidence that Xylella fastidiosa Can Cause Leaf Scorch Disease of Pecan

Plant Disease ◽

10.1094/pdis.2000.84.12.1282 ◽

2000 ◽

Vol 84 (12) ◽

pp. 1282-1286 ◽

Cited By ~ 24

Author(s):

R. S. Sanderlin ◽

K. I. Heyderich-Alger

Keyword(s):

Xylella Fastidiosa ◽

Carya Illinoinensis ◽

Symptom Development ◽

Koch’S Postulates ◽

Leaf Scorch ◽

Symptomatic Tissue ◽

Koch's Postulates ◽

Bacterial Leaf Scorch

The disease known as pecan fungal leaf scorch has been reported to be either caused by or associated with several fungi since it was first recognized in 1972. Data are presented that indicate the disease is initiated by the fastidious xylem-limited bacterium Xylella fastidiosa. X. fastidiosa was found consistently associated with fungal leaf scorch disease of pecan (Carya illinoinensis) in commercial orchards in Louisiana. It was generally not detected in symptomless trees. The disease was reproduced by inoculation of greenhouse seedlings and grafted trees with cultures of the bacterium obtained from leaves with fungal leaf scorch. The bacterium was reisolated from symptomatic tissue of inoculated pecan seedlings, but not from symptomless plants inoculated with water to complete Koch's postulates. It is proposed that the name of the disease be changed to pecan bacterial leaf scorch because fungi do not appear to be necessary for symptom development.

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Bacterial Leaf Scorch of Landscape Trees: What We Know and What We Do Not Know

Arboriculture & Urban Forestry ◽

10.48044/jauf.2007.043 ◽

2007 ◽

Vol 33 (6) ◽

pp. 376-385

Author(s):

James Sherald

Keyword(s):

Disease Management ◽

Urban Forest ◽

Xylella Fastidiosa ◽

Diagnostic Techniques ◽

Individual Tree ◽

Leaf Scorch ◽

Property Owners ◽

Symptom Awareness ◽

Landscape Trees ◽

Bacterial Leaf Scorch

Xylella fastidiosa has been recognized as a pathogen of landscape trees for over 25 years. Collectively, these diseases are referred to as bacterial leaf scorch (BLS). Arborists, property owners, and communities are now beginning to recognize BLS as a serious threat to the urban forest. Although advances in symptom awareness and diagnostic techniques have enabled arborists to diagnose BLS, there are many questions regarding host range, transmission, pathogeneses, disease management, and individual tree therapy that remain unanswered.

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First Report of Oleander Leaf Scorch Caused by Xylella fastidiosa in Florida

Plant Disease ◽

10.1094/pdis.2000.84.2.198b ◽

2000 ◽

Vol 84 (2) ◽

pp. 198-198 ◽

Cited By ~ 3

Author(s):

R. L. Wichman ◽

D. L. Hopkins ◽

T. A. Wichman

Keyword(s):

Xylella Fastidiosa ◽

Trisodium Citrate ◽

Nerium Oleander ◽

Sodium Ascorbate ◽

Eastern United States ◽

Pcr Assay ◽

First Report ◽

Leaf Scorch ◽

Chlorotic Mottling ◽

Specific Amplification

During the spring of 1998, mature oleanders (Nerium oleander L.), pruned to form a 2-m-high hedge along an interstate highway in Orlando, FL, were observed declining and dying. Numerous plants along a 200-m section of highway were in various stages of decline. Symptoms began as chlorotic mottling along the edges of leaves and as the disease progressed, mottling became more severe and leaf margins became necrotic. Scorched leaves died, and symptoms spread throughout the plants, resulting in defoliation. New growth from the base of affected plants was stunted and severely mottled. Petioles and leaf midribs were taken from leaves with mottling symptoms and assayed for the presence of Xylella fastidiosa by polymerase chain reaction (PCR) and culturing on periwinkle wilt agar medium. For PCR assay, infected tissue from three plants was extracted by grinding in SCP buffer (1.0 g of trisodium citrate and 1.0 g of disodium succinate per liter, in 0.015 M phosphate buffer, pH 7.0) containing 0.02 M sodium ascorbate and 5% acid-washed polyvinylpyrrolidone. Amplification was performed with primers RST31 and RST33, as previously described, for specific detection of X. fastidiosa strains (1). A X. fastidiosa-specific amplification product was produced from all three extracts. For culturing, petioles and leaf midribs were cut into 0.5-cm sections, and sap was extracted from the tissue by squeezing with a forceps. Sap was blotted directly onto the medium and incubated at 28°C. Colonies typical of X. fastidiosa were observed after 10 to 14 days of incubation, and single colonies were transferred to fresh periwinkle wilt agar. The colonies were confirmed as X. fastidiosa by PCR assay. Two of the oleander strains were used to inoculate three red and three white 18-month-old oleanders by needle-puncture of the stem through a cloudy drop of bacterium in SCP buffer (108 CFU/ml). For controls, three red and three white oleanders were inoculated with SCP buffer alone. After 9 weeks in a screenhouse, marginal leaf mottling was observed in both the red and white oleanders inoculated with X. fastidiosa, and the bacterium was reisolated from leaves as described above, completing Koch's postulates. Control plants remained symptomless. Oleander leaf scorch caused by X. fastidiosa has been described previously in California and Texas (2). This is the first report of oleander leaf scorch in Florida and the eastern United States. References: (1) G. V. Minsavage et al. Phytopathology 84:456, 1994. (2) A. H. Purcell et al. Phytopathology 89:53, 1999.

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