Alexander H Purcell

Alexander H Purcell
University of California, Berkeley | UCB · Department of Environmental Science, Policy, and Management

PhD 1974

About

159
Publications
23,151
Reads
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7,683
Citations
Introduction
My main interests are bacterial diseases of plants spread by insect vectors. Another interest is insect-bacteria interactions.
Additional affiliations
September 1974 - present
University of California, Berkeley
Position
  • Professor Emeritus
Description
  • Retired but active in research and consulting.
Education
September 1971 - May 1974
University of California, Davis
Field of study
  • Entomology
June 1960 - June 1964
US Air Force Academy, Colorado
Field of study
  • military science, humanities

Publications

Publications (159)
Article
Full-text available
The bacterium Xylella fastidiosa ( Xf ) is an invasive insect-borne pathogen, which causes lethal diseases to important crops including olives, citrus, almonds and grapes as well as numerous forest, ornamental, and uncultivated plants. Outbreaks of Xf -related plant diseases are currently occurring in the Mediterranean region, causing substantial l...
Article
The meadow spittlebug, Philaenus spumarius (Linnaeus) (Hemiptera: Aphrophoridae), is a vector of the plant pathogen Xylella fastidiosa; however, its role in recent outbreaks of Pierce’s disease of grapevine (PD) in California is unclear. While the phenology and ecology of P. spumarius can help determine its contributions to PD epidemics, both remai...
Preprint
Full-text available
The bacterium Xylella fastidiosa (Xf) is a worldwide distributed invasive insect-borne plant pathogen, which causes lethal diseases to many economically-important crops including olives, citrus, almonds and grapes as well as numerous forest, ornamental, and uncultivated plants. The Mediterranean basin is the top supplier of olive oil with 93% of th...
Article
Full-text available
Cicadas are prominent insects in the Mediterranean basin environments, including in olive orchards. The bacterium Xylella fastidiosa is a xylem-limited vector-borne plant pathogen that was introduced into southern Italy, causing significant losses of olive trees. Cicadas are xylem-sap feeders and potential vectors of X. fastidiosa; however, knowled...
Article
Full-text available
Following a request from the European Commission, the EFSA Plant Health Panel updated its pest categorisation of Xylella fastidiosa, previously delivered as part of the pest risk assessment published in 2015. X. fastidiosa is a Gram-negative bacterium, responsible for various plant diseases, including Pierce's disease, phony peach disease, citrus v...
Article
Full-text available
There is little information available on Xylella fastidiosa transmission by spittlebugs (Hemiptera, Cercopoidea). This group of insect vectors may be of epidemiological relevance in certain diseases, so it is important to better understand the basic parameters of X. fastidiosa transmission by spittlebugs. We used grapevines as a host plant and the...
Article
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The history of advances in research on Xylella fastidiosa provides excellent examples of how paradigms both advance and limit our scientific understanding of plant pathogens and the plant diseases they cause. I describe this from a personal perspective, having been directly involved with many persons who made paradigm-changing discoveries, beginnin...
Article
Full-text available
The bacterium Xylella fastidiosa (Xf), responsible for Pierce's disease (PD) of grapevine, colonizes the xylem conduits of vines, ultimately killing the plant. However, Vitis vinifera grapevine varieties differ in their susceptibility to Xf and numerous other plant species tolerate Xf populations without showing symptoms. The aim of this study was...
Article
Insects and mites can cause plant diseases or transport and inoculate viruses and microorganisms such as bacteria and fungi that cause plant disease. This chapter focuses on the plant dieases caused by insects. Insects are the most important vectors of plant viruses and the main or sole means of spread of many plant pathogens. Plant diseases spread...
Chapter
This chapter discusses the phytotoxicity, damage caused to plants by insects. Insects damage plants in many ways, but the most common type of damage is the removal of plant tissues, as in the familiar examples of caterpillars, beetles, and grasshoppers whose feeding creates noticeable holes or even the wholesale removal of leaves, fruits, or other...
Article
The relative titre of the causal agent of X-disease of stone fruits in the non-vector leafhopper Macrosteles fascifrons was tested by injecting dilutions of M. fascifrons extracts into non-infective Colladonus montanus leafhopper vectors. The recipient C. montanus were fed on celery test plants which were then observed for X-disease symptoms. M. fa...
Article
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We followed glassy-winged sharpshooter (GWSS) preference and age structure on ornamental host plants in Bakersfield, California. Averaging data across all sampling sites and collection dates, grape, citrus, apple, Xylosma, cherry and flowering pear were the most preferred ovipositional sites. GWSS nymphs were most often collected on oleander, flowe...
Article
Full-text available
Xylella fastidiosa is a xylem-limited bacterium transmitted to plants by xylem sap-feeding insects. This pathogen has a wide host range, causing disease in crops such as grape, citrus, almond, and coffee; ornamental plants; and trees. Sharpshooter leafhoppers are the major vectors of X. fastidiosa to crops of economic importance. Transmission chara...
Article
Full-text available
Colladonus montanus (Van Duzee), a lealhopper vector of X-disease phytoplasma (Xp), efficiently transmitted the pathogen to Arabidopsis thaliana Columbia wild type. During transmission trials, the phytoplasma was inoculated into 22-, 34-, and 40-day-old plants. Phytoplasma infections were confirmed by polymerase chain reaction (PCR) using primers s...
Article
Full-text available
The fate of Xylella fastidiosa, the bacterium that causes Pierce's disease of grape, was assessed in 29 species of plants associated with vineyards in California's San Joaquin Valley. Bacterial populations and movement in greenhouse-grown plants were measured 1, 3, and 9 weeks after mechanical and insect inoculation. X. fastidiosa was recovered in...
Article
Full-text available
Homalodisca coagulata (Say) is a sharpshooter leafhopper vector of the bacterial plant pathogen Xylella fastidiosa. Introduced into California about 15 years ago, this insect triggered recent outbreaks of Pierce's disease of grapevine in the state. H. coagulata has been observed feeding on dormant grapevines during the winter, raising the possibili...
Article
Full-text available
A simple defined solid medium containing citrate and succinate, three amino acids (L-glutamine, L-asparagine, and L-cysteine), hemin chloride, potato starch, gellan gum (GelRite), and mineral salts supported the growth of grape strains of Xylella fastidiosa, the bacterial pathogen that causes Pierce's disease of grape. Isolation efficiency from inf...
Article
Xylella fastidiosa, which causes Pierce's disease of grapevine and other important plant diseases, is a xylem-limited bacterium that depends on insect vectors for transmission. Although many studies have addressed disease symptom development and transmission of the pathogen by vectors, little is known about the bacterial mechanisms driving these pr...
Article
Full-text available
Xylophagous leafhopppers are common and abundant insects of tropical and subtropical environments and play important ecological roles in these ecosystems. The feeding biology of these insects is unique in terms of their high feeding rates and a digestive physiology that allows them to assimilate amino acids, organic acids, and sugars at approximate...
Article
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Strain KLN61 is an rpfF mutant strain of Xylella fastidiosa (Xf) that cannot be transmitted to plants by the sharpshooter leafhopper, Graphocephala atropunctata (BGSS), an efficient vector of the wild-type strain of this bacterium. This mutant was not retained and did not form biofilm in the vector mouthparts, however was hypervirulent and formed b...
Article
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Reporting Period: The results reported here are from work conducted from July 2004 to October 2004. ABSTRACT We have begun work on the effects of chemical and physical factors, including type of media, pH, media volume, and vessel on the in vitro survival, growth and substrate-attachment of a wild-type and mutant strain of Xylella fastidiosa (Xf)....
Article
Full-text available
Xylella fastidiosa is a xylem-limited bacterium that causes various diseases, among them Pierce's disease of grapevine (PD) and almond leaf scorch (ALS). PD and ALS have long been considered to be caused by the same strain of this pathogen, but recent genetic studies have revealed differences among X. fastidiosa isolated from these host plants. We...
Article
Full-text available
Xylella fastidiosa causes Pierce's disease of grapevine as well as several other major agricultural diseases but is a benign endophyte in most host plants. X. fastidiosa colonizes the xylem vessels of host plants and is transmitted by xylem sap-feeding insect vectors. To understand better the pattern of host colonization and its relationship to dis...
Article
Almeida, R. P. P., and Purcell, A. H. 2003. Homalodisca coagulata (Hemiptera, Cicadellidae) transmission of Xylella fastidiosa to almond. Plant Dis. 87:1255-1259. Almond leaf scorch (ALS) is caused by the bacterium Xylella fastidiosa, transmitted by sharp- shooter leafhoppers and spittlebugs. The recent invasion of a X. fastidiosa vector, Homalodis...
Article
Full-text available
Pierce's disease (PD) of grapevines is caused by a xylem-limited bacterium Xylella fastidiosa (Wells, Raju, Hung, Weisburg, Mandelco-Paul, and Brenner) that is transmitted to plants by xylem sap-feeding insects. The introduction of the sharpshooter leafhopper Homalodisca coagulata (Say) into California has initiated new PD epidemics in southern Cal...
Article
Full-text available
ABSTRACT The effects of date of inoculation on the development of Pierce's disease (PD) were evaluated in California grapevines during 1997 through 2000 at four locations. Some vines that had been inoculated either by using blue-green sharpshooters (Graphocephala atropunctata) as vectors or mechanically by needle puncture with the PD causal bacteri...
Article
Following the article in Pesticide Outlook by Alexander Purcell and Helene Feil from the Division of Insect Biology at the University of California, Berkeley, USA (Pesticide Outlook, 2001, 12(5), 199-203), the following is a summary of some recent research being conducted at USDA-ARS in the fight against this dangerous insect.
Article
Abstract 1. Natural populations of pea aphids in California contain at least two facultative bacterial secondary symbionts (pea aphid secondary symbiont, PASS, or pea aphid rickettsia, PAR) in a range of frequencies throughout the state. 2. Two pea aphid clones without either of these facultative associates failed to reproduce in the first 8 days a...
Article
Full-text available
Draft sequencing is a rapid and efficient method for determining the near-complete sequence of microbial genomes. Here we report a comparative analysis of one complete and two draft genome sequences of the phytopathogenic bacterium, Xylella fastidiosa , which causes serious disease in plants, including citrus, almond, and oleander. We present highl...
Article
Full-text available
Xylella fastidiosa (Xf) causes wilt disease in plants and is responsible for major economic and crop losses globally. Owing to the public importance of this phytopathogen we embarked on a comparative analysis of the complete genome of Xf pv citrus and the partial genomes of two recently sequenced strains of this species: Xf pv almond and Xf pv olea...
Article
Full-text available
A 2002 review of plant diseases caused by Xylella fastidiosa, historical highlights, recent and promising research developments.
Article
Xylella fastidiosa is a xylem-inhabiting bacterium that causes Pierce's disease (PD) of grapevine. Growth rates of X. fastidiosa in a rich liquid medium were determined by culturing methods at various temperatures. The slope of the regression line between the points of 18 and 28°C was similar to that reported for Escherichia coli between 12 and 30°...
Article
Alexander Purcell and Helene Feil from the Division of Insect Biology at the University of California, Berkeley, USA, outline how a new threat is transforming an old problem.
Article
Full-text available
Populations of cultivable cells of a citrus variegated chlorosis (CVC) disease strain of Xylella fastidiosa in stems and leaf veins of sweet orange (Citrus sinensis (L.) Osbeck) seedlings were estimated by dilution plating at 1, 2, 4, 8, and 16 weeks after needle inoculation. Cell populations ranged from log 4 to log 5 CFU/g of tissue after 1 week...
Article
Full-text available
Strains of Xylella fastidiosa isolated from grape, almond, maple, and oleander were characterized by enterobacterial repetitive intergenic consensus sequence-, repetitive extragenic palindromic element (REP)-, and random amplified polymorphic DNA (RAPD)-PCR; contour-clamped homogeneous electric field (CHEF) gel electrophoresis; plasmid content; and...
Article
The effects of two bacterial endosymbionts, designated PASS and PAR, were evaluated on the pea aphid, Acyrthosiphon pisum (Harris) (Hemiptera:Aphididae), in which they occur facultatively, and on the blue alfalfa aphid, A.kondoi Shinji, in which these bacteria have not been found in natural populations. Subclones of pea aphids and blue alfalfa aphi...
Article
Graphocephala atropunctata (Signoret) is the principal vector of Xylella fastidiosa (Wells, Raju, Hung, Weisberg, Mandelco-Paul and Brenner), the bacterium that causes Pierce's disease of grapevine in coastal California. Monitoring the activity of C. atropunctata in the early spring is important for timing insecticide sprays and assessing the poten...
Article
Full-text available
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...
Article
In southern California, populations of the western grapeleaf skeletonizer, Harrisina brillians Barnes & McDunnough, appear to be maintained at low levels of abundance by the combined activity of Harrisina brillians granulovirus (HbGV) and the parasitoid Ametadoria misella (Wulp). In contrast, outbreaks of H. brillians were common in central Califor...
Article
The fate of strains of the bacterium Xylella fastidiosa that cause Pierce's disease of grapevines was investigated in 33 species of mostly perennial plants common in riparian habitats in northern coastal California grape-growing regions. Plants were inoculated in the field with needle puncture using cultured cells of X, fastidiosa as inoculum or in...
Article
Interactions between a granulovirus (HbGV), a tachinid parasitoidAmetadoria misella,and their host, the western grapeleaf skeletonizerHarrisina brillians,were investigated. In field populations, the occurrence ofA. misellain HbGV-infectedH. brillianspupae was less frequent than would have been expected by random assortment of the virus and the para...
Article
Full-text available
ABSTRACT A lethal leaf scorch disease of oleander (Nerium oleander) appeared in southern California in 1993. A bacterium, Xylella fastidiosa, was detected by culturing, enzyme-linked immunoassay, and polymerase chain reaction in most symptomatic plants but not in symptomless plants or negative controls. Inoculating oleanders mechanically with X. fa...
Article
Wilkin Wai-Kuen Cheung and Alexander H. Purcell (1999) Invasion of bacteroids and BEV bacterium into oocytes of the leafhopper Euscelidius variegatus Kirschbaum (Homoptera: Cicadellidae): An electron microscopic study. Zoological Studies 38(1): 69-75. Electron microscopic studies were carried out on the infective stages of symbiotic bacteroids a an...