Observation and theory of whitefly-borne virus disease epidemics.

Author(s):  
J. Holt ◽  
J. Colvin
Plant Disease ◽  
2019 ◽  
Vol 103 (12) ◽  
pp. 3244-3250
Author(s):  
O. Domfeh ◽  
G. A. Ameyaw ◽  
H. K. Dzahini-Obiatey ◽  
L. E. del Río Mendoza

The spatiotemporal spread of cocoa swollen shoot virus disease (CSSVD), which is caused by cacao swollen shoot virus (CSSV) severe strain 1A in mixed hybrid cacao pre-inoculated with CSSV mild strain N1 (CSSV-N1), was investigated during a field experiment from 2006 to 2017, at the Cocoa Research Institute of Ghana. The development of disease epidemics has been described by the use of statistical modeling. Protecting all cacao plants with CSSV-N1 reduced the rate of CSSV-1A symptom appearance by 43% (P = 0.05) compared with the nonprotected control and by 33% compared with plots where cacao plants in the outer three or five rows were protected with CSSV-N1. Similarly, creating the protective outer rings three or five rows deep reduced the rate of CSSV-1A symptoms by 14% (P = 0.05) compared with the nonprotected control. CSSV-1A epidemics increased approximately 18% faster (P = 0.05) in transects oriented from the north and east compared with those oriented from the south and west. During the last 2 years of the study, CSSVD spread decreased significantly (P = 0.05) faster in plots where all test cacao plants were inoculated with CSSV-N1 compared with other treatments. The growth of cacao did not differ significantly among the treatments over the 9-year assessment period. Similarly, differences in the cumulative yield among the treatments over the 8-year assessment period were not significant.


Plant Disease ◽  
2009 ◽  
Vol 93 (7) ◽  
pp. 708-712 ◽  
Author(s):  
Murray Sharman ◽  
Denis M. Persley ◽  
John E. Thomas

Tobacco streak virus (TSV) was found to commonly occur in Parthenium hysterophorus, as symptomless infections, in central Queensland, Australia across a large area infested with this weed. Several isolates of TSV collected across the geographic range of P. hysterophorus were found to share identical coat protein sequence with each other and with TSV from crop plants in the same area. Seed transmission of TSV in P. hysterophorus was found to occur at rates of 6.8 to 48%. There was almost no change in the rate of TSV seed transmission when P. hysterophorus seed was stored for up to 24½ months. Implications of this relationship between TSV and P. hysterophorus for the development of virus disease epidemics in surrounding crops are discussed.


2015 ◽  
Vol 2 (1) ◽  
Author(s):  
Alexandra J. Weisberg ◽  
Haitham A. Elmarakeby ◽  
Lenwood S. Heath ◽  
Boris A. Vinatzer

Abstract Background.  Developing a universal standardized microbial typing and nomenclature system that provides phylogenetic and epidemiological information in real time has never been as urgent in public health as it is today. We previously proposed to use genome similarity as the basis for immediate and precise typing and naming of individual organisms or viruses. In this study, we tested the validity of the proposed system and applied it to the epidemiology of infectious diseases using Ebola virus disease (EVD) outbreaks as the example. Methods.  One hundred twenty-eight publicly available ebolavirus genomes were compared with each other, and average nucleotide identity (ANI) was calculated. The ANI was then used to assign unique codes, hereafter referred to as Life Ide.jpegication Numbers (LINs), to every viral isolate, whereby each LIN consisted of a series of positions reflecting increasing genome similarity. Congruence of LINs with phylogenetic and epidemiological relationships was then determined. Results.  Assigned LINs correlate with phylogeny at the species and infraspecies level and can even ide.jpegy some individual transmission chains during the 2014–2015 EVD epidemic in West Africa. Conclusions.  Life Ide.jpegication Numbers can provide a fast, automated, standardized, and scalable approach to precisely ide.jpegy and name viral isolates upon genome sequence submission, facilitating unambiguous communication during disease epidemics among clinicians, epidemiologists, and governments.


1998 ◽  
Vol 3 (1) ◽  
pp. 85
Author(s):  
M. R. Nelson ◽  
T. V. Orum

Recent advances in personal computer hardware and the rapid development of spatial analysis software that is user-friendly on PC's has provided remarkable new tools for the analysts of plant diseases, particularly ecologically complex virus diseases. Due to the complexity of the disease cycle of the animal-vectored plant virus, these diseases present the most interesting challenges for the application of spatial analysis technology. While traditional quantitative analysis of plant diseases concentrated on within-field spatial analysis, often involving rather arcane mathematical descriptions of pattern, the new spatial analysis tools are most useful at the dimension where many disease epidemics occur, the regional level. The output of many of the programs used in spatial analysis is a highly visual picture of a disease epidemic which has a strong intuitive appeal to managers of agricultural enterprises. Applications by us, thus far, have included tomato, pepper and cotton virus diseases in Arizona. Mexico, California and Pakistan. In addition, this technology has been applied by us to Phytophthora infestans in potato and tomato. Aspergillus flavus in cotton, and regional insect problems of tomato and cotton.


2016 ◽  
Vol 4 (3) ◽  
Author(s):  
Doudou Diop ◽  
Dirga Sakti Rambe

Plant Disease ◽  
2018 ◽  
Vol 102 (5) ◽  
pp. 837-854 ◽  
Author(s):  
M. J. Jeger ◽  
L. V. Madden ◽  
F. van den Bosch

In recent years, mathematical modeling has increasingly been used to complement experimental and observational studies of biological phenomena across different levels of organization. In this article, we consider the contribution of mathematical models developed using a wide range of techniques and uses to the study of plant virus disease epidemics. Our emphasis is on the extent to which models have contributed to answering biological questions and indeed raised questions related to the epidemiology and ecology of plant viruses and the diseases caused. In some cases, models have led to direct applications in disease control, but arguably their impact is better judged through their influence in guiding research direction and improving understanding across the characteristic spatiotemporal scales of plant virus epidemics. We restrict this article to plant virus diseases for reasons of length and to maintain focus even though we recognize that modeling has played a major and perhaps greater part in the epidemiology of other plant pathogen taxa, including vector-borne bacteria and phytoplasmas.


2010 ◽  
Vol 48 (1) ◽  
pp. 179-203 ◽  
Author(s):  
Roger A.C. Jones ◽  
Moin U. Salam ◽  
Timothy J. Maling ◽  
Arthur J. Diggle ◽  
Deborah J. Thackray

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