Pesticides are widely used in agricultural production to prevent or control pests, diseases, weeds, and other plant pathogens in an effort to reduce or eliminate yield losses and maintain high product quality. Although pesticides are developed through very strict regulation processes to function with reasonable certainty and minimal impact on human health and the environment, serious concerns have been raised about health risks resulting from occupational exposure and from residues in food and drinking water. Occupational exposure to pesticides often occurs in the case of agricultural workers in open fields and greenhouses, workers in the pesticide industry, and exterminators of house pests. Exposure of the general population to pesticides occurs primarily through eating food and drinking water contaminated with pesticide residues, whereas substantial exposure can also occur in or around the home. Regarding the adverse effects on the environment (water, soil and air contamination from leaching, runoff, and spray drift, as well as the detrimental effects on wildlife, fish, plants, and other non-target organisms), many of these effects depend on the toxicity of the pesticide, the measures taken during its application, the dosage applied, the adsorption on soil colloids, the weather conditions prevailing after application, and how long the pesticide persists in the environment. Therefore, the risk assessment of the impact of pesticides either on human health or on the environment is not an easy and particularly accurate process because of differences in the periods and levels of exposure, the types of pesticides used (regarding toxicity and persistence), and the environmental characteristics of the areas where pesticides are usually applied. Also, the number of the criteria used and the method of their implementation to assess the adverse effects of pesticides on human health could affect risk assessment and would possibly affect the characterization of the already approved pesticides and the approval of the new compounds in the near future. Thus, new tools or techniques with greater reliability than those already existing are needed to predict the potential hazards of pesticides and thus contribute to reduction of the adverse effects on human health and the environment. On the other hand, the implementation of alternative cropping systems that are less dependent on pesticides, the development of new pesticides with novel modes of action and improved safety profiles, and the improvement of the already used pesticide formulations towards safer formulations (e.g., microcapsule suspensions) could reduce the adverse effects of farming and particularly the toxic effects of pesticides. In addition, the use of appropriate and well-maintained spraying equipment along with taking all precautions that are required in all stages of pesticide handling could minimize human exposure to pesticides and their potential adverse effects on the environment.

A survey was conducted in the Macedonia region of Greece to determine the reservoir hosts of Tomato spotted wilt virus (TSWV) in three tobacco fields and in a greenhouse complex in which lettuce and the ornamentals chrysanthemum, gerbera, aster, and anemone were grown. Assays for TSWV infection were made by enzyme-linked immunosorbent assay on 6,172 plant samples, 3,909 from tobacco fields and 2,263 from the greenhouse complex, comprising plants of 208 species in 137 genera of 42 families. Plants of 86 species out of 63 genera of 27 families were infected of which 39 species are newly reported hosts of TSWV. An infection index was developed to evaluate the relative potential of each weed species as a virus source in both systems. Seventeen species in the tobacco fields and nine in the greenhouses had an infection index higher than one. Most species with infected plants were found in the Compositae family. Plants of some species occurring both in tobacco fields and in greenhouses were infected at only one of these sites. Frankliniella occidentalis was the common thrips species on weeds and crops in the greenhouses, while Thrips tabaci was the only vector on tobacco plants and weeds in the tobacco fields. This observation strongly suggests that the occurrence of species with infected plants and their number have to be attributed to the vector species prevailing in the greenhouse complex or tobacco fields, supporting the conclusion that TSWV is spread in two different epidemiological processes in Greece.

Influence of nitrogen on competition between winter cereals and sterile oat - Volume 49 Issue 1 - Kico V. Dhima, Ilias G. Eleftherohorinos