The Need for Pesticides

Disease-resistant varieties are attractive because they should pose little or no risk to the environment and enable growers to reduce and in some cases eliminate the need for pesticides. In some host-pathogen systems, resistance may persist for many years, but in others it may be short-lived (Koike et al., 2000). Unfortunately, resistance is not available to counter every disease and for some of the most damaging ones, such as tomato late blight (P. infestans) and white rot (Sclerotium cepivorum) of alliums, no acceptable resistant varieties are currently available. 

Crop rotation using a range of contrasting crops (including cover crops or a period of fallow) can decrease soilborne pathogen inocula, increase diversity in soil microflora over time and be unfavourable for the of spread foliar diseases in the shorter term. This reduces the need for pesticides. 

With emphasis on the need for pesticides in agriculture a BHC plant was commissioned in the private sector in 1952. A DDT plant in the public sector was established near Delhi in 1955. Production, which was only 462 tons in 1954-1955, increased to about 28,000 tons in 1968-1969. Other related pesticide products the country produces are organic phosphates, parathion, AlgP, methyl bromide, and ethylene dibromide, along with about 20 other compounds. 

Indirectly, this movement has also led to the development of agricultural biotechnology, a field that focuses on altering crop plants to reduce the need for pesticide applications. This includes research to develop plants that produce their own natural pesticide as well as crop plants that are resistant to synthetic pesticides. Plantings of bioengineered crops have rapidly increased in recent years and a majority of some crops grown in the United States are products of this technology. 

Having successfully made the transition from chemicals to bioscience, Monsanto pioneered the development of genetically modified crop seed that reduces the need for pesticides and herbicides. Company officials, however, never anticipated the major opposition from environmental groups, consumers, and antiglobalization activists, and the public fears of genetically modified foods. In 2000, then CEO Robert Shapiro admitted as much We learned that there is often a fine line between scientific confidence, on the one hand, and corporate arrogance on the other We didn t... 

Appropriate housekeeping standards to minimise the need for pesticide use... 

Chemical, cultural, and mechanical weed control practices have been relatively successful ia reducing yield losses from weeds (448). However, herbicide-resistant weed populations, soil erosion, pesticide persistence ia the environment, and other problems associated with technologies used (ca 1993) to control weeds have raised concerns for the long-term efficacy and sustainability of herbicide-dependent crop production practices (449). These concerns, coupled with ever-increasing demands for food and fiber, contribute to the need for innovative weed management strategies (450). 

Although SPME was applied initially for the analysis of relatively volatile environmental pollutants in waters, rapid developments have enabled SPME to be successfully applied for the analysis of pesticides in water, wine and more complex food samples such as honey, fruit juice and pears, vegetables and strawberries. With food samples, most analysts recognize the need for some sample pretreatment in order to minimize matrix effects. The matrix can affect the SPME efficiency, resulting in a reduced recovery of pesticides. The most common method is simply to dilute the sample or sample extract with water. Simpltcio and Boas comminuted pears in water prior to the determination of pesticides. Volante et al. extracted over 100 pesticides... 

The most widely regarded approach to accomplish the determination of as many pesticides as possible in as few steps as possible is to use MS detection. MS is considered a universally selective detection method because MS detects all compounds independently of elemental composition and further separates the signal into mass spectral scans to provide a high degree of selectivity. Unlike GC with selective detectors, or even atomic emission detection (AED), GC/MS may provide acceptable confirmation of the identity of analytes without the need for further information. This reduces the need to re-inject a sample into a separate GC system (usually GC/MS) for pesticide confirmation. Through the use of selected ion monitoring (SIM), efficient ion-trap or quadrupole devices, and/or tandem mass spectrometry (MS/MS), modern GC/MS instruments provide LODs similar to or lower than those of selective detectors, depending on the analytes, methods, and detectors. 

The chemical preservation of a sample is dependent on the chemistry of the ground-water (e.g., pH) and on the chemical characteristics of the pesticide being studied. Preservatives can be added to the sample containers in the field or prepared in advance at the laboratory. To determine the need for a chemical preservative in the field (i.e., pH analyses), test the groundwater collected during the purging process and not the sample collected for analysis. 

The fundamental chemistry, especially of the newer economic poisons, is of primary importance. The mechanism of action of the various types of economic poisons and the relation of structure to toxicity of insects are of fundamental interest. Chemical versus biological methods of evaluation should be presented. Performance methods of evaluation of these chemicals have been given careful consideration by several workers. Emphasis was placed by several workers on the need for much additional information on various aspects of the problem regarding the use of DDT, 2,4-D, and other pesticides. There is direct importance in studies on the metabolism of DDT. 

During 1948 in the same countries the imports of certain other pesticides increased greatly because of the need for locust control. It is to be expected that, after the locust outbreak subsides or is controlled, these imports will drop again. 

These and related problems are being encountered by the practicing physician with increasing frequency because of the wider and oftentimes injudicious use of the newer pesticidal toxicants. The need for information has been apparent for some time. However, the equal need for the coordination and integration of the existent information, so that it may become readily available to all who should have it, has not received adequate attention to date. 

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