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The growth of human populations is an important driving force in the accelerating changes that are occurring in the managed ecosystems on which we depend for food, fiber, and services, such as the maintenance of clean air and water. Human activities are measurably changing the composition of the atmosphere, adding carbon dioxide and methane, which alter the radiative balance of the planet, and chlorine gas, which destroys the ozone layers in the stratosphere. Humans have already destroyed vast tracts of tropical forests and agriculturally productive land. Industrial and human wastes have degraded some of the largest sources of fresh water. We are witnessing the rapid extinction of many species and the introduction of pests and infectious organisms into new environments, sometimes with calamitous results. There is an obvious need for increased attention to these problems and for research to find their solutions. Scholars who are expert in all aspects of environmental sciences will be required to understand the increasing stresses placed on the environment by the expanding human population and the concomitant growth of industry. Careers in this challenging field will require training in population biology, ecology, the social sciences, and related agriculture sciences.
Biologic Control of Plant Pests
The major increases in agricultural productivity that followed World War II were attributable in part to the widespread use of synthetic chemical pesticides for the control of insects, weeds, and plant pathogens. Initial successes have been followed by unexpected consequences, including injurious effects on nontarget organisms, contamination of soil and water with chemical residues, and the development of pesticide resistance, particularly among insects. In addition, the potential harmful effects of pesticides in the food chain offer considerable reason for concern.
There is a growing consensus that pest-management systems based on biologic control agents will provide a more desirable approach for resolving some of the current problems and reducing the use of synthetic pesticides. Achieving a shift to biologic control agents will, however, require the development of treatment strategies that are inexpensive, are easily applied, offer little or no hazard for nontarget organisms (including people), are equal in efficacy to or better than current pesticides, and are predictable under a range of environmental conditions. The successes in developing biologic control systems for insects have not been matched in progress toward commercial biologic control of plant pathogens or weeds. Unfortunately, the knowledge that is necessary to develop such biologic control agents will require a massive expansion of current research effort, and it will involve the complete spectrum of basic and applied life sciences.
Many of the major corporations involved in development of disease-control agents have closed research laboratories that have a primary assignment in biologic control agents. Emphasis has shifted to transgenic plants with insect-control characteristics or chemicals that turn on resistance mechanisms when applied to plants. Extensive growth in this type of research is foreseen. Some of the plant diseases that are most recalcitrant to all known control efforts are caused by soil borne pathogens. A deeper understanding of the complexities of the physical and biologic components of soil will require research on the microflora and microfauna of the leaf and root systems of plants going well beyond the bounds of our current knowledge. Furthermore, biologic control agents that are highly effective under greenhouse conditions are often ineffective or unpredictable when tested in the field and in different geographic regions. Thus, it is likely that extensive