Diseases under conservation tillage systems

1996 ◽  
Vol 76 (4) ◽  
pp. 635-639 ◽  
Author(s):  
K. L. Bailey

The primary focus of this paper is on the effects of tillage and residue management on some diseases of cereal and oilseed crops in western Canada. In this region, reduced tillage lowers the impact of some root diseases but increases the impact of foliar diseases on cereals. Published data showing evidence of the effect of reduced tillage on diseases of oilseed crops is scarce. Diseases that were less economically important under higher tillage regimes may become more important with reduced tillage, but location and local environment largely influence which diseases will be present. Crop rotation is a key factor in residue management for disease control. Disease and yield loss were higher with monoculture than with more diverse rotations. Some crops may pose a greater risk to succeeding susceptible crops that share common disease problems, such as Sclerotinia on peas and canola. A well-balanced rotation should be at least 4 yr long with 50% of the interval devoted to cereals and the remainder divided among pulses, flax, other oilseed crops, or forages. The risk of most diseases may be lowered by understanding and managing the interactions between pathogens and crop residue through modifying local environmental conditions, crop rotation, limited tillage, and antagonistic mycoflora. Single disease control measures may be inadequate with reduced tillage; a holistic approach to crop systems and plant health management may provide the solution to disease problems. Key words: Zero tillage, conventional tillage, crop rotation, disease control, cereals, oilseeds

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e4836 ◽  
Author(s):  
Marie-Pierre Hiel ◽  
Sophie Barbieux ◽  
Jérôme Pierreux ◽  
Claire Olivier ◽  
Guillaume Lobet ◽  
...  

Society is increasingly demanding a more sustainable management of agro-ecosystems in a context of climate change and an ever growing global population. The fate of crop residues is one of the important management aspects under debate, since it represents an unneglectable quantity of organic matter which can be kept in or removed from the agro-ecosystem. The topic of residue management is not new, but the need for global conclusion on the impact of crop residue management on the agro-ecosystem linked to local pedo-climatic conditions has become apparent with an increasing amount of studies showing a diversity of conclusions. This study specifically focusses on temperate climate and loamy soil using a seven-year data set. Between 2008 and 2016, we compared four contrasting residue management strategies differing in the amount of crop residues returned to the soil (incorporation vs. exportation of residues) and in the type of tillage (reduced tillage (10 cm depth) vs. conventional tillage (ploughing at 25 cm depth)) in a field experiment. We assessed the impact of the crop residue management on crop production (three crops—winter wheat, faba bean and maize—cultivated over six cropping seasons), soil organic carbon content, nitrate (${\mathrm{NO}}_{3}^{-}$), phosphorus (P) and potassium (K) soil content and uptake by the crops. The main differences came primarily from the tillage practice and less from the restitution or removal of residues. All years and crops combined, conventional tillage resulted in a yield advantage of 3.4% as compared to reduced tillage, which can be partly explained by a lower germination rate observed under reduced tillage, especially during drier years. On average, only small differences were observed for total organic carbon (TOC) content of the soil, but reduced tillage resulted in a very clear stratification of TOC and also of P and K content as compared to conventional tillage. We observed no effect of residue management on the ${\mathrm{NO}}_{3}^{-}$ content, since the effect of fertilization dominated the effect of residue management. To confirm the results and enhance early tendencies, we believe that the experiment should be followed up in the future to observe whether more consistent changes in the whole agro-ecosystem functioning are present on the long term when managing residues with contrasted strategies.


2007 ◽  
Vol 135 (7) ◽  
pp. 1124-1132 ◽  
Author(s):  
H.-P. DUERR ◽  
M. SCHWEHM ◽  
C. C. LEARY ◽  
S. J. De Vlas ◽  
M. EICHNER

SUMMARYPlanning adequate public health responses against emerging infectious diseases requires predictive tools to evaluate the impact of candidate intervention strategies. With current interest in pandemic influenza very high, modelling approaches have suggested antiviral treatment combined with targeted prophylaxis as an effective first-line intervention against an emerging influenza pandemic. To investigate how the effectiveness of such interventions depends on contact structure, we simulate the effects in networks with variable degree distributions. The infection attack rate can increase if the number of contacts per person is heterogeneous, implying the existence of high-degree individuals who are potential super-spreaders. The effectiveness of a socially targeted intervention suffers from heterogeneous contact patterns and depends on whether infection is predominantly transmitted to close or casual contacts. Our findings imply that the various contact networks' degree distributions as well as the allocation of contagiousness between close and casual contacts should be examined to identify appropriate strategies of disease control measures.


Author(s):  
Noluvuyo R. Magadla ◽  
Wilna Vosloo ◽  
Livio Heath ◽  
Bruce Gummow

African swine fever (ASF) has been reported in South Africa since the early 20th century. The disease has been controlled and confined to northern South Africa over the past 80 years by means of a well-defined boundary line, with strict control measures and movement restrictions north of this line. In 2012, the first outbreak of ASF outside the ASF control zone since 1996 occurred. The objective of this study was to evaluate the current relevance of the ASF control line as a demarcation line between endemic ASF (north) areas and ASF-free (south) area and to determine whether there was a need to realign its trajectory, given the recent outbreaks of ASF, global climate changes and urban development since the line’s inception. A study of ASF determinants was conducted in an area 20 km north and 20 km south of the ASF control line, in Limpopo, Mpumalanga, North West and Gauteng provinces between May 2008 and September 2012. The study confirmed that warthogs, warthog burrows and the soft tick reservoir, Ornithodoros moubata, are present south of the ASF control line, but no virus or viral DNA was detected in these ticks. There appears to be an increasing trend in the diurnal maximum temperature and a decrease in humidity along the line, but the impact of these changes is uncertain. No discernible changes in minimum temperatures and average rainfall along the disease control line were observed between 1992 and 2014. Even though the reservoirs were found south of the ASF boundary line, the study concluded that there was no need to realign the trajectory of the ASF disease control line, with the exception of Limpopo Province. However, the provincial surveillance programmes for the reservoir, vector and ASF virus south of this line needs to be maintained and intensified as changing farming practices may favour the spread of ASF virus beyond the control line.Keywords: African swine fever; warthog burrow; Ornithodoros moubata;control line


2004 ◽  
Vol 28 (2) ◽  
pp. 206 ◽  
Author(s):  
Priscilla Robinson

INFECTIOUS AND COMMUNICABLE DISEASES account for a large burden of disease worldwide, causing the death of roughly a million people each month (WHO 2004). This book is about some of the ways in which this enormous problem is being addressed. The book comprises a collection of papers from the global Conference on vaccines, prevention, and public health and is as much about public health thinking in communicable disease control as it is specifically about vaccines. Its contributors are practitioners in the field of immunisation and communicable disease control from all over the world. The book is clearly set out in eight sections, with both an introductory summary, Setting the stage, and an Epilogue summary section. The specific sections cover The present, with summaries of measles, rubella and poliovirus control measures, as well as the case of yellow fever which is used as a warning about what can happen if we take our eyes off the public-health-control ball. This is followed by The cutting edge, covering the newest vaccines for Haemophilus influenzae, varicella (chicken pox), hepatitis A, and the two major bacterial infections ? meningococcal and pneumococcal diseases. The future section covers prospects for vaccines to control a variety of infections, including the enteric diseases rotavirus, Shigella and typhoid; two major causes of cancer, Helicobacter pylori (gastric cancers and ulcers) and human papillomavirus (cervical cancer); hepatitis C; and two common causes of viral respiratory disease, influenza and respiratory syncytial virus (RSV). RSV is a good example of a common disease which carries a large burden of morbidity (Chin 2002) all over the world, especially among children, and yet few people have heard of it.


2021 ◽  
Author(s):  
Madison Stoddard ◽  
Debra Van Egeren ◽  
Kaitlyn Johnson ◽  
Smriti Rao ◽  
Josh Furgeson ◽  
...  

Abstract Background: The word ‘pandemic’ conjures dystopian images of bodies stacked in the streets and societies on the brink of collapse. Despite this frightening picture, denialism and noncompliance with public health measures are common in the historical record, for example during the 1918 Influenza pandemic or the 2015 Ebola epidemic. The unique characteristics of SARS-CoV-2—its high basic reproduction number (R0), time-limited natural immunity and considerable potential for asymptomatic spread—exacerbate the public health repercussions of noncompliance with interventions (such as vaccines and masks) to limit disease transmission. Our work explores the rationality and impact of noncompliance with COVID-19 disease control measures. Methods: In this work, we used game theory to explore when noncompliance confers a perceived benefit to individuals. We then used epidemiological modeling to predict the impact of noncompliance on control of COVID-19, demonstrating that the presence of a noncompliant subpopulation prevents suppression of disease spread. Results: Our modeling demonstrating that noncompliance is a Nash equilibrium under a broad set of conditions, and that the existence of a noncompliant population can result in extensive endemic disease in the long-term after a return to pre-pandemic social and economic activity. Endemic disease poses a threat for both compliant and noncompliant individuals; all community members are protected if complete suppression is achieved, which is only possible with a high degree of compliance. For interventions that are highly effective at preventing disease spread, however, the consequences of noncompliance are borne disproportionately by noncompliant individuals. Conclusions: In sum, our work demonstrates the limits of free-market approaches to compliance with disease control measures during a pandemic. The act of noncompliance with disease intervention measures creates a negative externality, rendering COVID-19 disease control ineffective in the short term and making complete suppression impossible in the long term. Our work underscores the importance of developing effective strategies for prophylaxis through public health measures aimed at complete suppression and the need to focus on compliance at a population level.


2020 ◽  
pp. 1-26
Author(s):  
MARGARET BROWN ◽  
MIKO JIANG ◽  
CHAYU YANG ◽  
JIN WANG

We present a new mathematical model to investigate the transmission dynamics of cholera under disease control measures that include education programs and water sanitation. The model incorporates the impact of education programs into the disease transmission rates and that of water sanitation into the environmental pathogen dynamics. We conduct a detailed analysis to the autonomous system of the model and establish the local and global stabilities of its equilibria that characterize the threshold dynamics of cholera. We then perform an optimal control study on the general model with time-dependent controls and explore effective approaches to implement the education programs and water sanitation while balancing their costs. Our analysis and simulation highlight the complex interaction among the direct and indirect transmission pathways of the disease, the intrinsic growth of the environmental pathogen and the impact of multiple control measures, and their roles in collectively shaping the transmission dynamics of cholera.


2018 ◽  
Vol 35 (1) ◽  
pp. 59-68 ◽  
Author(s):  
Sofia Hydbom ◽  
Johanna Alkan Olsson ◽  
Pål Axel Olsson

AbstractConventional agricultural practices can lead to soil erosion and a reduction in soil organic carbon (SOC) content. It has been suggested that less intensive agricultural practices, such as conservation tillage (including no-till and reduced till without soil inversion) may reduce both erosion and loss of SOC. The aim of this study was to determine whether, and why, conservation tillage is used in Scania, which is one of the most agro-intensive regions in Sweden. We also investigated how information on tillage practices is obtained, why one type of tillage may be favored over another, and whether some farmers are more likely to use conservation tillage. The result of this study will benefit policy makers and researchers by pinpointing factors that influence the use of conservation tillage. To collect data, a questionnaire was sent to farmers in Scania in 2016. We found that the majority of the responding farmers used conservation tillage, and that it was more likely to be used if the farmer was highly educated and spent more than 50% of their annual working time on crop production. The use of conservation tillage was also more common if the farm was large and clay soil dominated. Crop rotation was often highlighted as the most important factor influencing the choice of tillage practice, which may be due to crop species requirements. When asked to compare the consequences of reduced tillage and plowing, the perception of farmers using conservation tillage was in general more positive, indicating skepticism toward the practice of reduced tillage until it had been tried. We show that the use of conservation tillage, sometimes in combination with plowing, is widespread in Scania. However, unless changes in, for example, crop rotation and labor requirements occur, the use of conservation tillage will most likely remain the same as today, or only increase slightly in the near future. Farm enlargement may result in an increased conservation tillage use, and so may efforts to educate advisors, increased opportunities for peer-to-peer meetings, and the development of economically viable small farm solutions. Increased conservation tillage may be part of the solution for sustainable crop production, but drawbacks such as increased pesticide use must be addressed further, as well as factors such as crop rotation development and practical knowledge that influence conservation tillage use at the farm level.


2014 ◽  
Vol 35 (7) ◽  
pp. 810-817 ◽  
Author(s):  
Kyle B. Enfield ◽  
Nujhat N. Huq ◽  
Megan F. Gosseling ◽  
Darla J. Low ◽  
Kevin C. Hazen ◽  
...  

ObjectiveWe describe the efficacy of enhanced infection control measures, including those recommended in the Centers for Disease Control and Prevention’s 2012 carbapenem-resistant Enterobacteriaceae (CRE) toolkit, to control concurrent outbreaks of carbapenemase-producing Enterobacteriaceae (CPE) and extensively drug-resistantAcinetobacter baumannii(XDR-AB).DesignBefore-after intervention study.SettingFifteen-bed surgical trauma intensive care unit (ICU).MethodsWe investigated the impact of enhanced infection control measures in response to clusters of CPE and XDR-AB infections in an ICU from April 2009 to March 2010. Polymerase chain reaction was used to detect the presence ofblaKPCand resistance plasmids in CRE. Pulsed-field gel electrophoresis was performed to assess XDR-AB clonality. Enhanced infection-control measures were implemented in response to ongoing transmission of CPE and a new outbreak of XDR-AB. Efficacy was evaluated by comparing the incidence rate (IR) of CPE and XDR-AB before and after the implementation of these measures.ResultsThe IR of CPE for the 12 months before the implementation of enhanced measures was 7.77 cases per 1,000 patient-days, whereas the IR of XDR-AB for the 3 months before implementation was 6.79 cases per 1,000 patient-days. All examined CPE shared endemicblaKPCresistance plasmids, and 6 of the 7 XDR-AB isolates were clonal. Following institution of enhanced infection control measures, the CPE IR decreased to 1.22 cases per 1,000 patient-days (P= .001), and no more cases of XDR-AB were identified.ConclusionsUse of infection control measures described in the Centers for Disease Control and Prevention’s 2012 CRE toolkit was associated with a reduction in the IR of CPE and an interruption in XDR-AB transmission.


Soil Research ◽  
2016 ◽  
Vol 54 (6) ◽  
pp. 719 ◽  
Author(s):  
Jeremiah M. Okeyo ◽  
Jay Norton ◽  
Saidou Koala ◽  
Boaz Waswa ◽  
Job Kihara ◽  
...  

Sustainable farming practices are required to address the persistent problems of land degradation and declining crop productivity in Sub-Saharan Africa. Approaches such as reducing tillage and retaining crop residues as mulch are potential entry points for smallholder farmers to move towards sustainability. In this study, we assessed the impact of reduced tillage (RT) compared with conventional tillage (CT), each combined with crop residue reapplication, on soil quality indicators and crop yields under an 8-year trial in western Kenya. Our results indicate that RT combined with crop residue reapplication enhanced soil physical quality through increased macroaggregate (>2000µm) proportions and mean weight diameter. Similarly, lower respiratory quotient values indicate that soil microbes under RT have better substrate-use efficiency than those under CT. Nevertheless, soil organic carbon (C), potentially mineralisable C, microbial biomass C and mineral nitrogen contents were all higher under CT with crop residue incorporated into the soil. Maize grain yield and aboveground biomass were also higher under CT. Thus, despite RT showing potential to improve soil physical properties, CT performed better. A stepwise approach is proposed towards the practice of conservation agriculture under resource-constrained smallholder farming conditions, starting with increased biomass production to provide crop residue for soil cover, followed by RT approaches.


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