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Competency Area 7: Using Pesticides in an Environmentally Sound Manner

PO 43. Recognize how the following impact proper pesticide use in regard to water quality protection: soil characteristics, ground cover, proximity to water sources (surface water, groundwater, wells, etc.).

Pest management for water quality

The key to reducing the potential for pesticide contamination of water resources is the use of planned pest management. This may include avoiding unnecessary pesticide applications, use of targeted and economical applications, and use of cultural or biological practices that substitute for or complement pesticide use. In addition, pesticide selection and crop management should be carried out according to the site-specific needs for reduction of water contamination. The management plan requires evaluation of the nature of the water quality problem through consideration of the relative priorities for protection of various surface and groundwater resources, and the vulnerability of these water resources to contamination by pesticides.

Pesticide management practices

The evaluation of soil-pesticide interactions can be used to reduce the pollution potential of pesticides. First, the most effective pest control method should be selected. In cases in which various chemicals can economically be applied to remedy an infestation, the pesticide with the least environmental impact should be selected. This includes the evaluation of the site-specific leaching and surface loss potentials. In addition, the chemical's toxicity to human and aquatic life and the importance of the affected water bodies as drinking water supplies or natural habitats need to be considered.

Pesticides should be applied when they are most effective, which is influenced by temperature and moisture conditions. Pests under dormant or stressed conditions may be less susceptible to pesticide treatment. Pesticide efficacy can also be reduced by continuous use of pesticides of similar chemistry, which can cause pesticide resistance. Pesticide applications should be avoided under adverse weather conditions. This includes spraying under windy conditions, surface application before high-intensity rainfall and application on water-saturated soil. For volatile pesticides, application under high- temperature conditions should be avoided.

Finally, pollution from pesticides can be reduced by proper operation, safety, and maintenance practices, as listed in the New York Pesticide Applicator Training Manuals. Application equipment should be maintained in proper working condition. It should be calibrated at the beginning of the growing season and then re-calibrated regularly during the growing season. The required quantity of pesticide should be carefully measured to insure proper application rates and to prevent leftover tank mixes. If pesticides require dilution with water, prevention of backsiphoning to water supplies must be insured. Chemigation systems, which provide for pesticide application through irrigation, must be fitted with an appropriate anti-backsiphoning device.

Loading and mixing areas located near wells, high runoff areas or surface water bodies are a common source for contamination of surface or groundwater by pesticides. Sites for loading and mixing of pesticides should be located as far away from points of entry to surface or groundwater as possible. Wells which re used as a source for drinking water need especially be protected from pesticide contamination.

Comprehensive pest management plans allow for safe pesticide use and reduce the potential for contamination of water resources. Additional information on the judicious use of pesticides and how to protect and monitor the quality of water resources can be obtained from Cornell Cooperative Extension, the USDA Soil Conservation Service, the Department of Environmental Conservation, and the local Soil and Water Conservation Districts.

*This information was adapted from “Pesticide Management for Water Quality; Principles and Practices” Van Es, HM and Trautmann, NM. 1990. See  for more detailed information.