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 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 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.

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 Rootstock Effects on Almond Leaf Scorch Disease Incidence and Severity

Plant Disease ◽  
2016 ◽  
Vol 100 (8) ◽  
pp. 1617-1621 ◽  
Author(s):  
R. Krugner ◽  
C. A. Ledbetter
Keyword(s):  
Xylella Fastidiosa ◽  
Disease Incidence ◽  
Cross Sectional ◽  
Short Period ◽  
Symptom Remission ◽  
Second Year ◽  
Etiological Heterogeneity ◽  
Tree Performance ◽  
Severe Leaf ◽  
Almond Leaf Scorch

A 5-year field study was conducted to evaluate effects of duration and exclusion of Xylella fastidiosa infections on young almond tree performance and their links to tree vigor. ‘Nemaguard,’ ‘Okinawa,’ ‘Nonpareil,’ and Y119 were used as rootstocks for almond scion ‘Sonora.’ Among X. fastidiosa-infected trees, there was significant etiological heterogeneity with i) absence of leaf scorching symptoms in the presence of reduced growth, ii) presence of leaf scorching symptoms in the absence of reduced growth, and iii) severe leaf scorching and reduced growth. Trunk cross sectional areas of X. fastidiosa-infected trees grafted on ‘Nemaguard’ and ‘Nonpareil’ rootstocks were significantly smaller than noninfected trees, whereas trunk size of trees grafted on ‘Okinawa’ and Y119 was not affected by infection status. Severity of leaf scorching symptoms was highest on trees grafted on ‘Nonpareil’ rootstock, intermediate on ‘Okinawa’ and Y119, and lowest on ‘Nemaguard.’ X. fastidiosa infections and seasonal leaf scorching symptoms persisted on most inoculated trees throughout the study, except on trees grafted on ‘Nemaguard’ that manifested complete leaf scorching symptom remission and apparent elimination of the pathogen after the second year. Results indicate that depending on rootstock type X. fastidiosa can affect trunk size in a relatively short period and/or persist for years as trees grow.

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 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.

scholarly journals Phylogenetic inference enables reconstruction of a long-overlooked outbreak of almond leaf scorch disease (Xylella fastidiosa) in Europe

2020 ◽  
Vol 3 (1) ◽  
Author(s):  
Eduardo Moralejo ◽  
Margarita Gomila ◽  
Marina Montesinos ◽  
David Borràs ◽  
Aura Pascual ◽  
...  
Keyword(s):  
Fungal Pathogens ◽  
Xylella Fastidiosa ◽  
Epidemiological Data ◽  
Phylogenetic Inference ◽  
Posterior Density ◽  
Leaf Scorch ◽  
Almond Trees ◽  
Bayesian Phylogenetic Inference ◽  
Highest Posterior Density ◽  
Almond Leaf Scorch

Abstract The recent introductions of the bacterium Xylella fastidiosa (Xf) into Europe are linked to the international plant trade. However, both how and when these entries occurred remains poorly understood. Here, we show how almond scorch leaf disease, which affects ~79% of almond trees in Majorca (Spain) and was previously attributed to fungal pathogens, was in fact triggered by the introduction of Xf around 1993 and subsequently spread to grapevines (Pierceʼs disease). We reconstructed the progression of almond leaf scorch disease by using broad phylogenetic evidence supported by epidemiological data. Bayesian phylogenetic inference predicted that both Xf subspecies found in Majorca, fastidiosa ST1 (95% highest posterior density, HPD: 1990–1997) and multiplex ST81 (95% HPD: 1991–1998), shared their most recent common ancestors with Californian Xf populations associated with almonds and grapevines. Consistent with this chronology, Xf-DNA infections were identified in tree rings dating to 1998. Our findings uncover a previously unknown scenario in Europe and reveal how Pierce’s disease reached the continent.

scholarly journals Landscape Epidemiology of Xylella fastidiosa in the Balearic Islands

Agronomy ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 473
Author(s):  
Diego Olmo ◽  
Alicia Nieto ◽  
David Borràs ◽  
Marina Montesinos ◽  
Francesc Adrover ◽  
...  
Keyword(s):  
Xylella Fastidiosa ◽  
Vascular Plant ◽  
Western Mediterranean ◽  
Balearic Islands ◽  
Wild Plants ◽  
Pierce's Disease ◽  
Leaf Scorch ◽  
Pierce’S Disease ◽  
The Impact ◽  
Almond Leaf Scorch

Xylella fastidiosa (Xf) is a vascular plant pathogen native to the Americas. In 2013, it was first reported in Europe, implicated in a massive die-off of olive trees in Apulia, Italy. This finding prompted mandatory surveys across Europe, successively revealing that the bacterium was already established in some distant areas of the western Mediterranean. To date, the Balearic Islands (Spain) hold the major known genetic diversity of Xf in Europe. Since October 2016, four sequence types (ST) belonging to the subspecies fastidiosa (ST1), multiplex (ST7, ST81), and pauca (ST80) have been identified infecting 28 host species, including grapevines, almond, olive, and fig trees. ST1 causes Pierce’s disease (PD) and together with ST81 are responsible for almond leaf scorch disease (ALSD) in California, from where they were introduced into Mallorca in around 1993, very likely via infected almond scions brought for grafting. To date, almond leaf scorch disease affects over 81% of almond trees and Pierce’s disease is widespread in vineyards across Mallorca, although producing on average little economic impact. In this perspective, we present and analyze a large Xf-hosts database accumulated over four years of field surveys, laboratory sample analyses, and research to understand the underlying causes of Xf emergence and spread among crops and wild plants in the Balearic Islands. The impact of Xf on the landscape is discussed.

scholarly journals Two Xylella fastidiosa Genotypes Associated with Almond Leaf Scorch Disease on the Same Location in California

2005 ◽  
Vol 95 (6) ◽  
pp. 708-714 ◽  
Author(s):  
J. Chen ◽  
R. Groves ◽  
E. L. Civerolo ◽  
M. Viveros ◽  
M. Freeman ◽  
...  
Keyword(s):  
Xylella Fastidiosa ◽  
Genetic Locus ◽  
Rrna Gene ◽  
Polymorphism Analysis ◽  
Bacterial Colony ◽  
Mixed Genotype ◽  
Leaf Scorch ◽  
Mixed Genotype Infection ◽  
Genotype Infection ◽  
Almond Leaf Scorch

Almond leaf scorch disease (ALSD) has recently reemerged in the San Joaquin Valley of California threatening almond production. ALSD is caused by Xylella fastidiosa, a nutritionally fastidious bacterium. Single nucleotide polymorphisms (SNPs) in the 16S rRNA gene (16S rDNA) of X. fastidiosa strains were identified to characterize the bacterial population in infected trees. Genotype-specific SNPs were used to design primers for multiplex polymerase chain reaction assays of early passage cultures. Two genotypically distinct types of X. fastidiosa strains, G-type and A-type, coexist simultaneously in the same infected almond orchard. This was substantiated by restriction fragment length polymorphism analysis of a different genetic locus, RST31-RST33, which has previously been used to identify and differentiate X. fastidiosa strains. Furthermore, unique bacterial colony morphology was consistently associated with the A-type X. fastidiosa strains. To our knowledge, this is the first report of a mixed genotype infection of X. fastidiosa disease on the same location under natural environmental conditions. The concept of mixed genotype infection could affect the current epidemiological study based on the assumption that one genotype causes ALSD on one location and, therefore, the disease management strategy.

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