scholarly journals Spinach Downy Mildew: Advances in Our Understanding of the Disease Cycle and Prospects for Disease Management

Plant Disease ◽  
2019 ◽  
Vol 103 (5) ◽  
pp. 791-803 ◽  
Author(s):  
Shyam L. Kandel ◽  
Beiquan Mou ◽  
Nina Shishkoff ◽  
Ainong Shi ◽  
Krishna V. Subbarao ◽  
...  
Keyword(s):  
Disease Management ◽  
Downy Mildew ◽  
Management Strategies ◽  
Organic Production ◽  
Disease Cycle ◽  
The Past ◽  
Sexual Recombination ◽  
Oomycete Pathogen ◽  
Spinach Downy Mildew

Downy mildew on spinach is caused by Peronospora effusa, an oomycete pathogen that poses a challenge to spinach production worldwide, especially in organic production. Following infection, P. effusa produces abundant amounts of asexual sporangia. Sporangia become windborne and initiate new infections locally or distantly, leading to widespread epidemics. Oospores produced from the union of opposite mating types have been observed within infected leaves and seeds and may remain viable for many years. Sexual reproduction increases the genetic diversity of P. effusa through sexual recombination, and thus, the movement of oospores on seed has likely fueled the rapid explosion of new pathotypes in different regions of the world over the past 20 years. This review summarizes recent advances in spinach downy mildew research, especially in light of the findings of oospores in contemporary commercial spinach seed lots as well as their germination. Knowledge of the role of the oospores and other aspects of the disease cycle can directly translate into new and effective disease management strategies.

scholarly journals Three New Races of the Spinach Downy Mildew Pathogen Identified by a Modified Set of Spinach Differentials

Plant Disease ◽  
2007 ◽  
Vol 91 (11) ◽  
pp. 1392-1396 ◽  
Author(s):  
B. M. Irish ◽  
J. C. Correll ◽  
S. T. Koike ◽  
T. E. Morelock
Keyword(s):  
United States ◽  
European Union ◽  
Downy Mildew ◽  
The United States ◽  
The European Union ◽  
The Past ◽  
Differential Cultivars ◽  
Spinach Downy Mildew ◽  
New Races ◽  
Important Disease

Spinach downy mildew, caused by Peronospora farinosa f. sp. spinaciae, is the most economically important disease of spinach worldwide. During the past few years, spinach cultivars resistant to the seven previously described races of P. farinosa f. sp. spinaciae were observed to be severely affected by downy mildew in both the United States and the European Union. Four new isolates of P. farinosa f. sp. spinaciae were collected from California and The Netherlands and characterized based on disease reactions on two modified sets of spinach differentials. The results led to the description of three new races of the downy mildew pathogen, designated races 8, 9, and 10. Four differential cultivars with resistance to races 1 to 7 were used to distinguish the three new races. Dolphin was susceptible to races 8 and 10 but resistant to race 9; Lion was susceptible to race 10 but resistant to races 8 and 9; Lazio was resistant to races 1 to 7 as well as races 8, 9, and 10; and Tarpy was susceptible to all three new races. The three new races also were used to evaluate the disease reactions on 43 contemporary commercial spinach cultivars in greenhouse trials. A survey of 58 isolates of P. farinosa f. sp. spinaciae collected in California and Arizona between 2004 and 2006 revealed that race 10 predominated in the areas sampled.

scholarly journals The role of adhering floral tissues in sclerotinia disease of kiwifruit

2000 ◽  
Vol 53 ◽  
pp. 138-142 ◽  
Author(s):  
S. Hoyte
Keyword(s):  
Disease Management ◽  
Sclerotinia Sclerotiorum ◽  
Management Strategies ◽  
Field Trials

Field trials in 10 Bay of Plenty and two Waikato orchards during 1996/98 investigated the role of adhering floral tissues in the development of sclerotinia disease of kiwifruit caused by Sclerotinia sclerotiorum Petalfall and stamenfall extended over a period of at least six weeks S sclerotiorum was isolated from 053 of petals during flowering and 042 from adhering floral tissues on fruit Fruit from two orchards had a significantly higher incidence of fruit scarring on fruit with adhering floral tissues compared to fruit without adhering floral tissues The incidence of diseased fruitlets and fruit scarring was significantly reduced when floral tissues were physically removed after petalfall The data suggest that floral tissues are readily colonised by S sclerotiorum ascospores during flowering and that disease mostly arises directly from mycelial infection originating within adhering floral tissues This disease pathway will be exploited in developing disease management strategies

Do sociodemographic characteristics associated with the use of CAM differ by chronic disease?

2019 ◽  
Vol 29 (4) ◽  
pp. 655-660 ◽  
Author(s):  
Sabine Drieskens ◽  
Jean Tafforeau ◽  
Stefaan Demarest
Keyword(s):  
Disease Management ◽  
Musculoskeletal Diseases ◽  
Conventional Medicine ◽  
Statistical Significance ◽  
Severe Headache ◽  
Sociodemographic Characteristics ◽  
The Past ◽  
Interview Survey ◽  
Cam Use

AbstractBackgroundComplementary and alternative medicine (CAM) is oftenused to alleviate the discomfort, disability and pain involved in many chronic diseases. Besides this, females, middle-aged and higher educated people are also known to use CAM the most. This study explores whether the sociodemographic characteristics associated with CAM use differ by type of disease.MethodsThe following data were taken from the Belgian Health Interview Survey 2013 for the individuals aged 15+ years (n = 8942): sociodemographic characteristics, past 12-month diseases (using a list) and contact with a homeopath, chiropractor, acupuncturist and/or osteopath (CAM-therapists) in the past year. The association between CAM use and disease, controlled for gender, age, education and conventional medicine use, was assessed through logistic regressions. When interactions with the sociodemographic characteristics were found, stratified regressions were conducted.ResultsPeople with musculoskeletal diseases [odds ratio (OR) = 2.6], allergy (OR = 1.4) and severe headache (OR = 1.5) had higher odds of using CAM in the past year with statistical significance. For musculoskeletal diseases, the odds of using CAM was higher, with statistical significance, for every sociodemographic subclass. For allergy, CAM use was higher among men, people aged 45+ years and lower educated people, while for severe headache CAM use was higher among women, people aged 45+ years and higher educated people, all with statistical significance.ConclusionsSociodemographic characteristics associated with CAM use differ by diseases. The role of CAM in disease management cannot be ignored. Making physicians aware for which disease CAM is used and by whom, may facilitate disease management.

scholarly journals Genetic diversity of the spinach downy mildew pathogen based on hierarchical sampling

2020 ◽  
Author(s):  
Chunda Feng ◽  
Kurt Lamour ◽  
Braham Deep Singh Dhillon ◽  
Maria Isabel Villarroel-Zeballos ◽  
Vanina Lilian Castroagudin ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Downy Mildew ◽  
Rapid Evolution ◽  
Sexual And Asexual Reproduction ◽  
Evolution Of Virulence ◽  
Reproduction Strategies ◽  
Oomycete Pathogen ◽  
Spinach Downy Mildew ◽  
New Races ◽  
Important Disease

AbstractDowny mildew, caused by the obligate oomycete pathogen Peronospora effusa, is the most economically important disease of spinach. In the past 30 years, 14 new races and 13 strains with novel virulence have been identified. However, the mechanism(s) driving the rapid evolution of virulence remains unknown. To understand reproductive strategies potentially driving the emergence of new races in P. effusa, 67 composite isolates (a collection of symptomatic leaves from a single cultivar grown in a defined area) of P. effusa obtained from 13 states between 2010 and 2018 were used to analyze the population genetic diversity hierarchically. Genotypes at 33 SNP loci of 719 lesions from these 67 isolates were determined by targeted sequencing. Diversity was then evaluated among individual lesions within the composite isolates, between isolates, host cultivars, geographic locations, and years of isolates collected. A total of 380 genotypes were identified from 719 individual lesions. Of the 380 genotypes, 350 (92%) were unique while the most common genotype was identified in 110 lesions of 16 isolates collected from 13 cultivars from CA and AZ in 2016. Variation within composite isolates ranged from none (a single genotype among lesions from a composite isolate) to 38 unique genotypes recovered from 39 lesions of a composite isolate. An index of association analysis suggested asexual (clonal) and sexual reproduction play important roles in population structure. Based on discriminant analysis of principal components, four distinct subpopulations were identified. Host cultivar, origin, and time of collection had an effect on population differentiation, and genotypes specific to a certain location or collection period were identified. Some subpopulations were unique to certain areas, and were only detected after 2014-2016. The co-existence of sexual and asexual reproduction strategies may partially explain the rapid emergence and spread of new races and novel strains of P. effusa.

scholarly journals Spinach Growers Value Host Resistance and Synthetic Fungicides in the Fight against Downy Mildew

2020 ◽  
Author(s):  
Robin A. Choudhury ◽  
Neil McRoberts
Keyword(s):  
Downy Mildew ◽  
Online Survey ◽  
Control Strategies ◽  
Management Strategies ◽  
Control Measures ◽  
Resistant Varieties ◽  
Synthetic Pesticides ◽  
Spinach Downy Mildew ◽  
Organic Pesticides ◽  
Downy Mildew Disease

AbstractCalifornia spinach growers struggle to manage spinach downy mildew disease. The disease is especially difficult in the organic crop, which currently relies on resistant varieties to maintain disease-free crop. Alternative control measures are available, but it is not clear how growers perceive the efficacy of these methods. It is also not clear who growers contact to find out information on spinach downy mildew disease management. In this study, we conducted an online survey of people involved in spinach production, asking about their beliefs in the efficacy of different control methods and who they contact frequently to discuss spinach downy mildew control. We found that respondents were most positive about the efficacy of resistant varieties and synthetic pesticides, with much lower perceived efficacy for the practices of disking diseased fields, roguing diseased plants, and organic pesticides. Growers most frequently contacted pest control advisors (PCAs) about management strategies for spinach downy mildew. These results suggest that respondents are most confident about the efficacy of resistant varieties and synthetic pesticides and may be hesitant to adopt new control strategies like organic pesticides. The results also suggest that future extension efforts can be focused on PCAs to reach the most stakeholders with up to date research on downy mildew control.

A new kind of radio: FM broadcasting in India

2014 ◽  
Vol 36 (8) ◽  
pp. 1084-1099 ◽  
Author(s):  
Biswarup Sen
Keyword(s):  
Management Strategies ◽  
Profound Change ◽  
The Past ◽  
Fm Radio ◽  
The Social ◽  
Structure Programming ◽  
History Of ◽  
Business Structure

In 2001, India’s first private FM station – Radio City, Bangalore – came on air, ending an era of state broadcasting that began in 1930. In the past decade, FM radio has enjoyed spectacular success: over 200 stations are now in operation, and the FM industry has seen spectacular growth in listenership and revenues. FM’s impact goes beyond economics; it is now a cultural signifier synonymous with modernity – as the ‘tagline’ for a popular FM network puts it ‘Radio Mirchi – it’s hot!’ FM, I argue in this article, represents a new kind of radio. The shift from state-controlled, nationwide AM transmission to corporate-owned local FM broadcasting signals a profound change in the very philosophy of radio in India. This article offers a brief account of the history of Indian radio and analyzes the social and economic factors that necessitated a change in modes of broadcasting. It also brings its claims into focus through using a case study that looks at the business structure, programming policies, and audience management strategies of one very popular FM station – Radio Mirchi, Kolkata – in order to demonstrate how these newly shaped practices are reinventing the role of radio in contemporary India.

scholarly journals Identification of New Races and Deviating Strains of the Spinach Downy Mildew Pathogen Peronospora farinosa f. sp. spinaciae

Plant Disease ◽  
2014 ◽  
Vol 98 (1) ◽  
pp. 145-152 ◽  
Author(s):  
Chunda Feng ◽  
James C. Correll ◽  
Katherine E. Kammeijer ◽  
Steven T. Koike
Keyword(s):  
Downy Mildew ◽  
Spinacia Oleracea ◽  
Resistance Locus ◽  
Rapid Rate ◽  
The Past ◽  
Differential Cultivars ◽  
Spinach Downy Mildew ◽  
New Races ◽  
Obligate Pathogen ◽  
Downy Mildew Disease

Spinach downy mildew disease, caused by the obligate pathogen Peronospora farinosa f. sp. spinaciae, is the most economically important spinach (Spinacia oleracea) disease. New races of this pathogen have been emerging at a rapid rate over the last 15 years. This is likely due to production changes, particularly in California, such as high-density plantings and year-round spinach production. As of 2004, 10 races of P. farinosa f. sp. spinaciae had been identified, and the spinach resistance locus RPF2 provided resistance to races 1 to 10. Based on disease reactions on a set of spinach differentials containing six hypothesized resistance loci (RPF1-RPF6), races 11, 12, 13, and 14 of P. farinosa f. sp. spinaciae were characterized based on samples collected in the past 5 years as part of this study. Race 11, identified in 2008, could overcome the resistance of spinach cultivars resistant to races 1 to 10. Spinach resistance loci RPF1, RPF3, and RPF6 provided resistance to race 11. Race 12 was identified in 2009 and could overcome the resistances of the RPF1 and RPF2 loci. The RPF3 locus was effective against race 12. Race 13 was identified in 2010 and could overcome the resistance imparted by the RPF2 and RPF3 loci, whereas the RPF1 locus was effective against race 13. Race 14 was similar to race 12 and caused identical disease responses on the standard differentials but could be distinguished from race 12 by its ability to cause disease on a number of newly released cultivars, including ‘Pigeon’, ‘Cello’, and ‘Celesta’. Five novel strains of P. farinosa f. sp. spinaciae were also identified. For example, isolate UA4711 of the pathogen, collected from Spain in 2011, was able to overcome the resistance imparted by the RPF1 and RPF3 loci, while RPF2 and RPF4 were effective against this strain. A total of 116 spinach cultivars, including 103 commercial lines and 13 differential cultivars, were evaluated for resistance to race 10 and the newly designated races 11, 12, 13, and 14.

scholarly journals The Role of Modeling and Synthesis in Creative Mitigation

2020 ◽  
Vol 8 (3) ◽  
pp. 263-274 ◽  
Author(s):  
Michael Heilen
Keyword(s):  
Management Strategies ◽  
The United States ◽  
Cultural Resource Management ◽  
Cultural Resources ◽  
The Public ◽  
Effective Strategies ◽  
The Past ◽  
National Historic Preservation Act ◽  
Do So

AbstractIn the 54 years since passage of the National Historic Preservation Act, more than 56 million ha of land have been surveyed in the United States, and nearly one million cultural resources have been identified and recorded. These efforts have produced hundreds of thousands of project reports, vast collections of data, and a wealth of descriptive information about the past. The accumulated data can be used to generate important new knowledge about the past, with many scientific and management implications, but remain largely untapped. Following current approaches, many resources will be damaged or lost before effective strategies for studying or preserving them can be developed. Synthesis and modeling are needed in creative mitigation efforts to identify which resources to preserve and study and how best to do so with limited time and funding. This article explores the potential for compiling and synthesizing large cultural and environmental datasets within a geographic information system to model the nature and distribution of cultural resources. It is argued that dedicated synthesis and modeling of cultural resource management data will allow development of more effective and proactive research and management strategies, providing lasting benefit to diverse scientific and traditional communities and the public.

scholarly journals Genome Sequences of Three Races of Peronospora effusa: A Resource for Studying the Evolution of the Spinach Downy Mildew Pathogen

2018 ◽  
Vol 31 (12) ◽  
pp. 1230-1231 ◽  
Author(s):  
Chunda Feng ◽  
Kurt H. Lamour ◽  
Burt H. Bluhm ◽  
Sandeep Sharma ◽  
Sandesh Shrestha ◽  
...  
Keyword(s):  
Downy Mildew ◽  
Genome Sequences ◽  
Oomycete Pathogen ◽  
Spinach Downy Mildew ◽  
New Races ◽  
Downy Mildew Disease

Downy mildew disease, caused by the obligate oomycete pathogen Peronospora effusa, is the most important economic constraint for spinach production. Three races (races 12, 13, and 14) of P. effusa have been sequenced and assembled. The draft genomes of these three races have been deposited to GenBank and provide useful resources for dissecting the interaction between the host and the pathogen and may provide a framework for determining the mechanism by which new races of the pathogen are rapidly emerging.

Real-Time PCR Detection of the Onion Downy Mildew Pathogen Peronospora destructor From Symptomless Onion Seedlings and Soils

Plant Disease ◽  
2021 ◽  
pp. PDIS-05-20-1095
Author(s):  
Kazuki Fujiwara ◽  
Hiroyoshi Inoue ◽  
Ryoichi Sonoda ◽  
Yutaka Iwamoto ◽  
Motoaki Kusaba ◽  
...  
Keyword(s):  
Disease Management ◽  
Real Time ◽  
Downy Mildew ◽  
Real Time Pcr ◽  
Management Strategies ◽  
Leaf Tissue ◽  
Asymptomatic Infection ◽  
Inoculum Sources ◽  
Peronospora Destructor ◽  
Pathogen Dna

An outbreak of downy mildew disease of onion, caused by Peronospora destructor, in Japan in 2016 necessitated a reevaluation of the primary inoculum sources to optimize disease management. Detection of the P. destructor pathogen in plants with asymptomatic infection and in soil would guide the application of fungicides according to the extent of infection before disease development. Here, we detected P. destructor in both plants and soil using newly developed primer sets (Pd ITS and Pd ITS 614) by both conventional and real-time PCR. Validation by real-time PCR with Pd ITS 614 showed that P. destructor DNA was amplified from symptomless seedlings at 3.7 × 102 to 1.0 × 100 conidium cells/50 mg leaf tissue, suggesting the detection of asymptomatic infection. Real-time PCR with Pd ITS amplified pathogen DNA from field soils at 1.6 × 103 to 8.3 × 101 oospore cells/g of soil. This real-time PCR assay provides a useful tool for identifying and quantifying inoculum sources, which may be the foundation of the design of integrated disease management strategies.

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