Potency of plant products in control of virus diseases of plants.

Author(s):  
H. N. Verma ◽  
V. K. Baranwal
Author(s):  
O. E. Bradfute

Electron microscopy is frequently used in preliminary diagnosis of plant virus diseases by surveying negatively stained preparations of crude extracts of leaf samples. A major limitation of this method is the time required to survey grids when the concentration of virus particles (VPs) is low. A rapid survey of grids for VPs is reported here; the method employs a low magnification, out-of-focus Search Mode similar to that used for low dose electron microscopy of radiation sensitive specimens. A higher magnification, in-focus Confirm Mode is used to photograph or confirm the detection of VPs. Setting up the Search Mode by obtaining an out-of-focus image of the specimen in diffraction (K. H. Downing and W. Chiu, private communications) and pre-aligning the image in Search Mode with the image in Confirm Mode facilitates rapid switching between Modes.


1950 ◽  
Vol 34 (6) ◽  
pp. 1637-1652
Author(s):  
Thomas M. Durant ◽  
Charles R. Shuman

1963 ◽  
Vol 02 (02) ◽  
pp. 49-51 ◽  
Author(s):  
K. Knapp ◽  
W. Lenz

SummaryIn 1961 an increase in certain congenital malformations was noticed in various parts of the Federal Republic of Germany. From the outset, it seemed very probable that a single cause was responsible, since, although these malformations varied, they appeared to belong to one and the same syndrome. For general reasons, such causes as radioactivity, contraceptives, attempted abortions or virus diseases did not provide an acceptable explanation. The epidemiology was, however, suggestive of some chemical substance taken orally.After thalidomide had been indicated in several histories, suspicion of that drug was aroused and, within one week, intake of it could be proved or was found to be very likely in 17 out of 20 cases, while in the remaining cases it could not be excluded. Though this first result was highly significant, we were at first reluctant to incriminate thalidomide definitely, because there was still some doubt about the reliability of the histories. But within a few weeks, the thalidomide aetiology received support from many sources. Specific studies on limited material are sometimes superior to extensive, broadly planned investigations.


2020 ◽  
Vol 1 (1) ◽  
pp. 51-57
Author(s):  
Meghnath Dhimal ◽  
Tamanna Neupane ◽  
Samir Kumar Adhikari ◽  
Pradip Gyanwali

We are facing global pandemic of novel corona virus diseases COVID-19 which is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). This paper is aimed to assess trend of COVID-19 cases and health sector response in Nepal. We reviewed WHO databases to observe the global trends and epidemiology of COVID-19 as well as daily situation updated reports of Health Emergency and Operation Centre (HEOC), guidelines, national and international government documents. The first case of COVID was reported in Nepal on 23 January 2020 and number of cases reached 454 on 21 May 2020. In order to address the increasing number of cases of COVID-19, Government of Nepal is adopting various preventive measures like extending lockdown period, setting up quarantine and isolation facilities, sealing borders, suspending flights, closing public places etc. There is need of joint effort by individuals, communities and government to prevent the further spread and flatten epidemic curve in Nepal.


2015 ◽  
Vol 54 (2) ◽  
pp. 98-106 ◽  
Author(s):  
F. Hutton ◽  
J.H. Spink ◽  
D. Griffin ◽  
S. Kildea ◽  
D. Bonner ◽  
...  

Abstract Virus diseases are of key importance in potato production and in particular for the production of disease-free potato seed. However, there is little known about the frequency and distribution of potato virus diseases in Ireland. Despite a large number of samples being tested each year, the data has never been collated either within or across years. Information from all known potato virus testing carried out in the years 2006–2012 by the Department of Agriculture Food and Marine was collated to give an indication of the distribution and incidence of potato virus in Ireland. It was found that there was significant variation between regions, varieties, years and seed classes. A definition of daily weather data suitable for aphid flight was developed, which accounted for a significant proportion of the variation in virus incidence between years. This use of weather data to predict virus risk could be developed to form the basis of an integrated pest management approach for aphid control in Irish potato crops.


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