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A number of challenges, e. This necessitates an increase in crop productivity with less environmental impact while maintaining good food quality and food security. Methods and output The aim of these systematic maps is to compile scientific evidence for different plant disease protection strategies for the main arable crops grown in Sweden. Six major crops wheat, barley, oat, potato, sugar beet and oilseed rape have been selected based on the area under production, the annual production, the economic importance, and the amount of pesticide used against diseases in these crops in Sweden. All methods to manage diseases will be considered, including cropping system, pesticide application, biological control methods, as well as combinations of methods and integrated pest management. These systematic maps will only deal with field studies of relevance for agricultural practices in Sweden, although we expect that the results will be applicable for northern Europe as a whole.
Potato planted at higher altitude had a lower incidence and severity of PBW but this needs to be tested under field conditions in different areas and at different altitudes. Knowledge of PBW detection, spread and management is scarce and haphazard, leading to insufficient management techniques among interviewed farmers from the different districts. Possible explanations of the presence and widespread distribution of PBW in all study districts may be that PBW has been present in Rwanda for many years Van der Zaag , the seed system is mainly informal and the movement and exchange of potatoes locally is uncontrolled USAID Our findings of higher PBW incidence and severity in minor potato growing areas are consistent with the findings of Scott who recorded higher PBW incidence in the southern and eastern districts of Rwanda where potato is currently a minor crop.
Higher disease incidence and severity in these areas suggest inadequate extension services, targeting non-priority crops and biophysical factors that may not be optimal for potatoes Verdoodt and Van Ranst Additionally, in these areas potato is continuously grown to secure food but continuous growing of potatoes in infested soils increases PBW incidence and severity Muthoni et al. The association of low PBW incidence and severity with high altitude of cropping sites is in agreement with the findings of Ateka et al.
Elphinstone found that as altitude increased, average temperature and incidence of bacterial wilt decreased. Ciampi et al. Strains of R. In this study, the proportion of latent infections of plants in the fields was not assessed.
The finding in this study that crop rotation is highly associated with low incidence and severity of PBW echo earlier studies Kakuhenzire et al.
In Uganda, rotating potatoes with wheat, sweet potato, maize, millet, carrots, sorghum, or beans reduced wilt incidence and increased yields of potatoes Katafiire et al. However, one season without potato, as practiced by the farmers in this study is too short for elimination of the pathogen in infested fields.
Gildemacher et al. The reduction in disease incidence by intercropping and wide spacing that we found is due to increased distances between individual potato plants and the presence of the root systems of other plant species between the potato plants Autrique and Potts Wide spacing significantly reduced incidence and severity of PBW Tables 5 and 6.
By increasing the spacing between potato plants through intercropping, incidence of PBW incidence as well as rate of disease development could be significantly reduced Autrique and Potts A large proportion of farmers in this study exchange farm tools Table S 3 , probably because they are encouraged to consolidate their land and work together in groups, associations or cooperatives using their own farm tools on different farms Kathiresan However, this practice should be accompanied with tool sterilization since the exchange of farm tools resulted in higher PBW incidence and severity.
It is mainly through PBW infected soil adhering to tools that PBW disease is spread between different fields if tools are not sterilized before and after use in each field. The options for tools sterilization include passing them through a flame or using sodium hypochlorite household bleach or JIK Sharma et al.
But not all farmers can afford sodium hypochlorite and there is lack of knowledge among farmers of the importance of tools sterilization Table S 3. Farmers should be sensitized to the importance of sterilizing tools. Methods for sterilizing tools in a safe and appropriate manner need to be developed. In both plant and public health epidemiology, the association of diseases and risk factors have been demonstrated Breslow ; Willett ; Savary et al. For instance, analysing risk factors using logistic regression provided estimates of the contribution of climatic years, wheat varieties, and crop management to the likelihood of epidemic occurrence in wheat Savary et al.
Similarly, Jones et al. The farmers interviewed were aware that PBW is a major threat to their potato production and ranked it as the major disease constraint Fig. The reason is that fungicide sprays can be used for late blight control, but no equivalent control measure is available for PBW control.
Conversely, previous studies Bicamumpaka and Haverkort ; Devaux et al. Most of the farmers in this study identified PBW symptoms mainly based on wilting plants and rotting tubers. These findings are similar to results of a survey performed in Kenya by Kwambai et al. Limited PBW knowledge by the farmers in Rwanda is probably due to the inaccessibility of accurate information since most of the farmers received their information about PBW mainly from their fellow farmers and relatives.
Some of the farmers interviewed were aware of different PBW management methods. However, the awareness of management methods did not always agree with their attitudes to managing the disease. Once it was mainly a matter of content, but today it is almost impossible to identify the author of that content or even to determine whether the author is a person or a computer program.
Soon we may lose our sense of what the norm actually is and what would be a deviation from it, an ERROR. But how to deal with the irritation? What does it take to avoid being deceived by appearances in the digital age? Principles of order are necessary for people and the societies we build. However, these rules are never set in stone — like ourselves and our society, they are subject to constant change.
Rules are made, not only to be followed, but to be broken.
But how do we maintain the delicate balance between accepting our rules and breaking them when necessary? How does this evaluation relate to the society and culture in which it is made and how does it change over time?
Only when we analyze them can we determine their cause and document their consequences.