Analysis and Visualisation of Research Trends in Almond Leaf Scorch

2020 ◽  
Vol 12 (sp3) ◽  
Keyword(s):  
Research Trends ◽  
Leaf Scorch ◽  
Almond Leaf Scorch

scholarly journals Effects of Almond Leaf Scorch Disease on Almond Yield: Implications for Management

Plant Disease ◽  
2008 ◽  
Vol 92 (3) ◽  
pp. 409-414 ◽  
Author(s):  
Mark S. Sisterson ◽  
Jianchi Chen ◽  
Mario A. Viveros ◽  
Edwin L. Civerolo ◽  
Craig Ledbetter ◽  
...  
Keyword(s):  
Yield Loss ◽  
Disease Incidence ◽  
Central Valley ◽  
Effective Management ◽  
Leaf Scorch ◽  
Lost Productivity ◽  
Direct Contrast ◽  
Management Techniques ◽  
Simple Economic ◽  
Almond Leaf Scorch

Almond leaf scorch (ALS) disease has been present in California's almond-growing regions for over 60 years. This disease is caused by the bacterium Xylella fastidiosa and the pathogen is vectored by xylem-feeding sharpshooters and spittlebugs. Currently, there are no effective management techniques that prevent trees from becoming infected. Within affected orchards throughout California's Central Valley, disease incidence and the risk of tree-to-tree spread appears to be low. Consequently, the decision to remove or keep infected trees depends on lost productivity. We compared yield and vitality between infected and uninfected almond for cvs. Sonora and Nonpareil. Sonora was examined at three sites over 3 years and Nonpareil was examined at one site over 2 years. Yields of ALS-affected trees were significantly lower for both cultivars, although yield losses of Sonora were proportionally greater than those of Nonpareil. Yields of infected trees did not decline incrementally over years; rather, they fluctuated similarly to those of uninfected trees. In addition, no infected trees died during the course of the study. These results are in direct contrast to previous anecdotal reports which suggest that yields of infected trees incrementally decline and infected trees eventually die. A simple economic model was developed to determine conditions under which rouging infected trees would increase returns. Based on the model, orchard age, yield loss due to infection, and the value of a maximally producing almond tree should be considered when deciding to remove ALS-affected trees.

A New Sharpshooter Threatens Both Crops and Ornamentals

2000 ◽  
Vol 1 (1) ◽  
pp. 4 ◽  
Author(s):  
Matthew J. Blua ◽  
Phil A. Phillips ◽  
Richard A. Redak
Keyword(s):  
Host Range ◽  
Potential Distribution ◽  
Xylella Fastidiosa ◽  
New Disease ◽  
Leaf Scorch ◽  
Economic Problems ◽  
The Future ◽  
Different Strains ◽  
Large Host ◽  
Almond Leaf Scorch

The glassy-winged sharpshooter (Homalodisca coagulate), an insect that has recently invaded California, and the smoke tree sharpshooter (Homalodisca lacerta) are creating serious new economic problems in both agricultural and ornamental plantings. The greatest threats surround their ability to spread the plantpathogenic bacterium Xylella fastidiosa, which induces Pierce's disease in grapevines, almond leaf scorch disease, and a new disease known as oleander leaf scorch. Because of the potential distribution and large host range of the glassywinged sharpshooter, other diseases caused by different strains of X. fastidiosa may have an even greater impact on the state's agricultural and ornamental landscape industries in the future. Posted 27 June 2000.

scholarly journals Influence of Inoculation Date on the Colonization of Xylella fastidiosa and the Persistence of Almond Leaf Scorch Disease Among Almond Cultivars

Plant Disease ◽  
2011 ◽  
Vol 95 (2) ◽  
pp. 158-165 ◽  
Author(s):  
Tiesen Cao ◽  
Joseph H. Connell ◽  
Margot Wilhelm ◽  
Bruce C. Kirkpatrick
Keyword(s):  
Xylella Fastidiosa ◽  
Prunus Dulcis ◽  
Current Season ◽  
Leaf Scorch ◽  
Growing Seasons ◽  
Almond Trees ◽  
Cultivar Susceptibility ◽  
June July ◽  
July August September ◽  
Almond Leaf Scorch

Field grown 2-year-old almond trees (Prunus dulcis cvs. Butte, Carmel, Mission, Ne Plus Ultra, Padre, Peerless, Price, Solano, Sonora, and Thompson) were mechanically inoculated with Xylella fastidiosa in the growing seasons of 2002 and 2003 to study the effect of inoculation date on the movement and colonization of X. fastidiosa and the overwintering persistence of almond leaf scorch disease (ALS) in these cultivars. X. fastidiosa was inoculated into the base of current-season growing shoots in April, May, June, July, August, September, and October. Almond trees inoculated in spring months developed more ALS-symptomatic leaves and more extensive within-plant spread of X. fastidiosa by the end of the current growing season compared with trees inoculated in July, August, September, and October. Trees inoculated in June developed the most severe ALS symptoms during the season in which they were inoculated. Trees inoculated in June and July 2002 had significantly higher disease ratings in 2003 than inoculations made in August and October 2002. Based on disease ratings observed in 2003, 1 year after inoculation, Sonora and Solano were the most ALS susceptible, Mission and Price intermediate, and Carmel, Padre, Ne Plus Ultra, Butte, Peerless, and Thompson were the least susceptible cultivars for allowing X. fastidiosa to overwinter and cause disease the following year. Assessment of all trees in August 2004 indicated that trees inoculated in June and July 2002 had a significantly higher amount of ALS-infected branches than trees inoculated in other months. Butte, Carmel, Padre, and Thompson cultivars had no symptomatic branches, while X. fastidiosa infections persisted or colonized new branches in Sonora, Solano, Peerless, Price, Mission, and Ne Plus Ultra. Based on the 2004 assessment, Sonora was the most susceptible cultivar. Surveys of a diseased orchard in Chico, CA showed large differences in ALS incidence in four almond cultivars. Nonpareil and Peerless had significantly greater incidence of disease than Butte and Carmel over the 2 years surveyed. These data suggest that cultivar susceptibility and the time of X. fastidiosa infection are important factors in determining the persistence of ALS in almond trees.

scholarly journals Almond Leaf Scorch Disease Development on Almond Branches High-Grafted on Peach Rootstock

Plant Disease ◽  
2013 ◽  
Vol 97 (2) ◽  
pp. 277-281 ◽  
Author(s):  
Tiesen Cao ◽  
Theodore M. DeJong ◽  
Bruce C. Kirkpatrick
Keyword(s):  
Xylella Fastidiosa ◽  
Average Distance ◽  
Winter Season ◽  
Growing Season ◽  
Prunus Dulcis ◽  
Leaf Scorch ◽  
Second Year ◽  
Peach Rootstocks ◽  
Almond Leaf Scorch ◽  
Made In

Development of almond leaf scorch (ALS) disease was monitored on young almond (Prunus dulcis ‘NePlus’ and ‘Peerless’) shoots produced from almond scion wood that was high-grafted on peach rootstocks (P. persica ‘Queencrest/Nemaguard’), after the almond shoots were mechanically inoculated with Xylella fastidiosa. The objective of this study was to evaluate the potential movement of X. fastidiosa through almond–peach graft unions. ALS symptoms developed on both X. fastidiosa-inoculated and uninoculated almond shoots that were high-grafted on different peach limbs of the same tree in September following inoculations with X. fastidiosa made in June and July 2002, respectively, when the average distance in peach rootstock between the two almond–peach graft unions was 30.5 cm or shorter. No ALS symptoms were observed on uninoculated almond shoots late in the growing season of the second year. The incidence of ALS-affected leaves on shoots inoculated with X. fastidiosa decreased in the second year on the inoculated shoots of Peerless as determined by the number of inoculated shoots showing ALS symptoms in 2002 versus 2003. No visible ALS symptoms were observed in NePlus late in the growing season of the second year, suggesting that survival of X. fastidiosa in NePlus was less than in Peerless. These data demonstrate that movement of X. fastidiosa through two almond–peach graft unions was possible during the year of inoculation when the peach rootstock stem distance between the two almond–peach graft unions was minimal. However, X. fastidiosa may not survive the winter season or survived so poorly as not to be able to produce ALS symptoms in the second growing season on the uninoculated shoots that previously showed ALS symptoms in the fall of the year when an adjacent shoot was inoculated. The results suggest that high-grafting almond scion wood on multiple peach rootstock limbs may provide a means to limit movement of X. fastidiosa from one almond limb to another on the same tree.

scholarly journals Multilocus Simple Sequence Repeat Markers for Differentiating Strains and Evaluating Genetic Diversity of Xylella fastidiosa

2005 ◽  
Vol 71 (8) ◽  
pp. 4888-4892 ◽  
Author(s):  
Hong Lin ◽  
Edwin L. Civerolo ◽  
Rong Hu ◽  
Samuel Barros ◽  
Marta Francis ◽  
...  
Keyword(s):  
Simple Sequence Repeat ◽  
Xylella Fastidiosa ◽  
Sequence Repeat ◽  
Leaf Scorch ◽  
Genome Wide ◽  
A Genome ◽  
Genome Wide Search ◽  
Ssr Loci ◽  
Simple Sequence ◽  
Almond Leaf Scorch

ABSTRACT A genome-wide search was performed to identify simple sequence repeat (SSR) loci among the available sequence databases from four strains of Xylella fastidiosa (strains causing Pierce's disease, citrus variegated chlorosis, almond leaf scorch, and oleander leaf scorch). Thirty-four SSR loci were selected for SSR primer design and were validated in PCR experiments. These multilocus SSR primers, distributed across the X. fastidiosa genome, clearly differentiated and clustered X. fastidiosa strains collected from grape, almond, citrus, and oleander. They are well suited for differentiating strains and studying X. fastidiosa epidemiology and population genetics.

scholarly journals Glassy-Winged Sharpshooters Expected to Increase Plant Disease

2000 ◽  
Vol 1 (1) ◽  
pp. 3 ◽  
Author(s):  
Alexander H. Purcell ◽  
Stuart R. Saunders
Keyword(s):  
Plant Disease ◽  
Plant Diseases ◽  
Pierce's Disease ◽  
Leaf Scorch ◽  
Pierce’S Disease ◽  
Almond Trees ◽  
Citrus Orchards ◽  
Almond Orchards ◽  
A Minor ◽  
Almond Leaf Scorch

As it moves through California, the new pest known as glassy-winged sharpshooter (GWSS) may significantly increase the spread of plant diseases caused by the bacterium Xylella fastidiosa. The bacterium causes Pierce's disease of grapevines, almond leaf scorch and the newly recognized oleander leaf scorch disease. Currently, almond leaf scorch is a minor problem for California's almonds, but if GWSS becomes established in significant numbers in or near almond orchards, it might increase the incidence of almond leaf scorch. Our studies show that GWSS and two other sharpshooter species can transmit X. fastidiosa from diseased oleanders to healthy oleanders. GWSS also can transmit Pierce's disease strains of the bacterium from grapevine to grapevine and to almond trees. The oleander strain of the bacterium did not infect grapevines, but the ability of GWSS to transmit Pierce's disease strains may increase the spread of this lethal grapevine disease in vineyards bordering citrus orchards or other habitats where invading GWSS may establish permanent populations. Posted 27 December 2000.

scholarly journals Population Structure of Xylella fastidiosa Associated with Almond Leaf Scorch Disease in the San Joaquin Valley of California

2015 ◽  
Vol 105 (6) ◽  
pp. 825-832 ◽  
Author(s):  
Hong Lin ◽  
Md Sajedul Islam ◽  
Juan C. Cabrera-La Rosa ◽  
Edwin L. Civerolo ◽  
Russell L. Groves
Keyword(s):  
Population Structure ◽  
Driving Forces ◽  
Xylella Fastidiosa ◽  
Prunus Dulcis ◽  
San Joaquin Valley ◽  
Leaf Scorch ◽  
Ssr Analysis ◽  
Cultivar Selection ◽  
Genetic Clusters ◽  
Almond Leaf Scorch

Xylella fastidiosa causes disease in many commercial crops, including almond leaf scorch (ALS) disease in susceptible almond (Prunus dulcis). In this study, genetic diversity and population structure of X. fastidiosa associated with ALS disease were evaluated. Isolates obtained from two almond orchards in Fresno and Kern County in the San Joaquin Valley of California were analyzed for two successive years. Multilocus simple-sequence repeat (SSR) analysis revealed two major genetic clusters that were associated with two host cultivars, ‘Sonora’ and ‘Nonpareil’, respectively, regardless of the year of study or location of the orchard. These relationships suggest that host cultivar selection and adaptation are major driving forces shaping ALS X. fastidiosa population structure in the San Joaquin Valley. This finding will provide insight into understanding pathogen adaptation and host selection in the context of ALS disease dynamics.

scholarly journals Leaf Scorch of Purple-Leafed Plum and Sweetgum Dieback: Two New Diseases in Southern California Caused by Xylella fastidiosa Strains with Different Host Ranges

Plant Disease ◽  
2009 ◽  
Vol 93 (11) ◽  
pp. 1131-1138 ◽  
Author(s):  
R. Hernandez-Martinez ◽  
D. A. Cooksey ◽  
F. P. Wong
Keyword(s):  
Southern California ◽  
Xylella Fastidiosa ◽  
Liquidambar Styraciflua ◽  
Pierce's Disease ◽  
Enzyme Linked Immunosorbent Assay ◽  
Leaf Scorch ◽  
Pierce’S Disease ◽  
Prunus Cerasifera ◽  
Almond Leaf Scorch

Sweetgum dieback and leaf scorch of purple-leafed plum are two new diseases of southern California landscape ornamentals. Samplings were conducted in 2003 and 2004 and 28 of 105 sweetgum (Liquidambar styraciflua) and 38 of 62 purple-leafed plum (Prunus cerasifera) plants tested positive for Xylella fastidiosa by enzyme linked immunosorbent assay. In all, 3 strains of X. fastidiosa were isolated from sweetgum and 13 from purple-leafed plum. All sweetgum strains and some purple-leafed plum strains grew on PW but not PD3 media. Strain PC045 from purple-leafed plum and strain LS022 from sweetgum were inoculated into their original hosts in addition to almond, oleander, and grapevine plants. Sweetgum plants also were inoculated with strains causing Pierce's disease, almond leaf scorch, and oleander leaf scorch. Strain PC045 caused symptoms in purple-leafed plum and almond plants within 6 months, and the pathogen was recovered from 93 and 100% of inoculated plants, respectively. Inoculation of grapevine and oleander plants with PC045 did not result in disease or recovery of the pathogen. In all, 5 of 25 sweetgum plants inoculated with LS022 showed symptoms after 9 months, and the pathogen was recovered from 3 of these plants. Inoculation of grapevine, oleander, and almond with LS022 resulted in no disease or recovery of the pathogen from the plants. A strain of Pierce's disease, a strain of oleander leaf scorch, and two strains from almond did not cause disease in sweetgum. These results confirm the role of X. fastidiosa strains as pathogens of purple-leafed plum and sweetgum, and that strains from sweetgum are unique in their host range.

scholarly journals Hypervariations of a Protease-Encoding Gene, PD0218 (pspB), in Xylella fastidiosa Strains Causing Almond Leaf Scorch and Pierce's Disease in California

2008 ◽  
Vol 74 (12) ◽  
pp. 3652-3657 ◽  
Author(s):  
J. Chen ◽  
E. Civerolo ◽  
K. Tubajika ◽  
S. Livingston ◽  
B. Higbee
Keyword(s):  
Genetic Variation ◽  
Tandem Repeats ◽  
Xylella Fastidiosa ◽  
Pierce's Disease ◽  
Rrna Gene ◽  
Leaf Scorch ◽  
Pierce’S Disease ◽  
Putative Protease ◽  
Encoding Gene ◽  
Almond Leaf Scorch

ABSTRACT Xylella fastidiosa is a gram-negative plant pathogenic bacterium that causes almond leaf scorch disease (ALSD) and Pierce's disease (PD) of grape in many regions of North America and Mexico. Of the two 16S rRNA gene genotypes described in California, A genotype strains cause ALSD only and G genotype strains cause both PD and ALSD. While G genotype strains cause two different diseases, little is known about their genetic variation. In this study, we identified a putative protease locus, PD0218 (pspB), in the genome of X. fastidiosa and evaluated the variation at this locus in X. fastidiosa populations. PD0218 contains tandem repeats of ACDCCA, translated to threonine and proline (TP), upstream of the putative protease conserved domain. Among 116 X. fastidiosa ALSD and PD strains isolated from seven locations in California, tandem repeat numbers (TRNs) varied from 9 to 47, with a total of 30 TRN genotypes, indicating that X. fastidiosa possesses an active mechanism for contracting and expanding tandem repeats at this locus. Significant TRN variation was found among PD strains (mean = 29.9), which could be further divided into two TRN groups: PD-Gsmall (mean = 17.3) and PD-Glarge (mean = 44.3). Less variation was found in ALSD strains (mean = 21.7). The variation was even smaller after ALSD strains were subdivided into the A and G genotypes (mean = 13.3, for the G genotype; mean = 27.1, for the A genotype). Genetic variation at the PD0218 locus is potentially useful for sensitive discrimination of X. fastidiosa strains. However, TRN stability, variation range, and correlation to phenotypes should be evaluated in epidemiological applications such as pathotype identification and delineation of pathogen origin.

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