2I – Forest Chemical Management

Management Measure

Use chemicals when necessary for forest management in accordance with the following to reduce NPS pollution impacts due to the movement of forest chemicals offsite during and after application:

  1. Ensure that applications are performed by skilled and licensed applicators according to the registered use, with special consideration given to impacts on nearby surface waters.
  2. Carefully prescribe the type and amount of pesticides appropriate for the insect, fungus, or herbaceous species.
  3. Prior to applications of pesticides and fertilizers, inspect the mixing and loading process and the calibration of equipment, and identify the appropriate weather conditions, the spray area, and buffer areas for surface waters and mixing and loading areas.
  4. Establish and identify buffer areas for surface waters to protect beneficial uses. (This is especially important for aerial applications.)
  5. Immediately report accidental spills of pesticides or fertilizers into surface waters to the California Office of Emergency Services (Cal/OES). Develop an effective spill contingency plan to contain spills.

Management Practices

  • Pesticides and fertilizers are occasionally used in forestry to reduce mortality of desired tree species and improve forest production. Because pesticides can be toxic if misused, they must be mixed, transported, loaded, and applied correctly (according to label instructions) to prevent potential NPS pollution. Fertilizers can also be toxic or can shift the ecosystem’s energy dynamics when used improperly, so it is important that they also be handled and applied in accordance with instructions on the label (USEPA, 2002).

  • Methods of chemical application
    Generally, chemicals are applied by hand, from an airplane or helicopter (aerial spray), or mechanically. When forest chemicals are applied mechanically, it is most common to use a vehicle-mounted boom sprayer. The cost of chemical management depends on the method of application. Hand application costs approximately $100 per acre, while aerial application is less expensive at $55 to $70 per acre.

    Using slow-release fertilizers when possible can reduce adverse impacts on the environment. This practice reduces potential nutrient leaching to ground water and it increases the availability of nutrients for plant uptake. Fertilizers should be applied during maximum plant uptake periods to minimize leaching. Fertilizers and herbicides should not be used in streams or Streamside Management Areas. If designed properly, forested buffer areas around watercourses can effectively reduce adverse effects on water quality from fertilizers (Megahan, 1980).

    Riekerk and others (1989) found that the greatest risk to water quality from pesticide application in forestry operations occurred from aerial application because of drift, wash-off, and erosion processes. They found that aerial applications of herbicides resulted in surface runoff concentrations roughly 3.5 times greater than those for application on the ground. Therefore, where possible, aerial application of pesticides should be avoided. Alternatively, tree injection or hand application of herbicides should be used. Research results suggest that tree injection application methods, although labor intensive, are the least hazardous for water pollution (Riekerk et al., 1989).

    When aerial spray applications are used, drift or accidental application of chemicals directly to surface waters should be avoided. Appropriate buffer widths should be determined by considering the altitude of application, weather conditions, and drop size distribution. Careful and precise marking of application areas for aerial applications helps avoid accidental contamination of open waters (USEPA, 2002).

    Pesticides and fertilizers should be applied only during favorable atmospheric conditions. Pesticides should not be applied when wind conditions increase the likelihood of significant drift. It is also best to avoid pesticide application when temperatures are high or relative humidity is low because these conditions influence the rate of evaporation and enhance losses of volatile pesticides.

  • Following the label
    Pesticide users need to abide by the current pesticide label, which could specify the following: whether users be trained and certified in the proper use of the pesticide; allowable use rates; safe handling, storage, and disposal requirements; and whether the pesticide may be used only under the provisions of an approved State Pesticide Management Plan.

  • Spill prevention
    Areas where mixing, loading, and equipment cleaning occur should be located where pesticide residues cannot enter streams or other water bodies. Pesticide wastes and containers should be disposed of according to State and federal laws and precautions should be taken to prevent leaks and spills.

  • Integrated pest management
    Ideally, the use of pesticides should be considered as only one part of an overall program to control pest problems. Integrated Pest Management (IPM) strategies have been developed to control forest pests without total reliance on chemical pesticides. The IPM approach uses all available techniques, including both chemical and nonchemical methods. An extensive knowledge of both the pest and the ecology of the affected environment is necessary for IPM to be effective.


  • California Department of Forestry and Fire Protection Pest Management Program protects the State’s forest resources from native and introduced pests, conduct surveys and provide technical assistance to private forest landowners, and promote forest health on all forest lands.

  • California Department of Pesticide Regulation has programs to protect human health and the environment by regulating the sale and use of pesticides, and by fostering reduced-risk pest management in California.

Information Resources

  • Forest Stewardship Program, Pest Management is an article about pest management in forests.
  • Forest Stewardship Program, Tree Notes is a series of short papers produced by the California Department of Forestry and Fire Protection to provide information on various pests and threats to forests. These resources are available from the local forester at any CDF Unit or call or write Jesse Rios, Forest Pest Specialist, P.O. Box 944246, Sacramento, CA 94244 (Telephone: 916-653-9476).
  • SWRCB, NPS Encyclopedia management measure 1D: Pesticide Management.
  • University of California Statewide Integrated Pest Management Program develops and promotes the use of integrated, ecologically sound pest management programs in California. UC IPM’s mission is to reduce the pesticide load in the environment and develop pest control programs that are economically, environmentally, and socially acceptable.
  • University of California Statewide Integrated Pest Management Program, Forest and Right-of-Way Pest Control this guide book is a guide to pest management in forests, as well as rights-of-way and commercial nurseries. It is geared specifically toward pesticide professionals in California.
  • USDA Enterprise Team has two components. The core component, sponsored by Forest Health Protection, supports the Forest Service in meeting its legal mandate for the protection of forest health. The entrepreneurial component builds the team's capacity to fulfill its mission by providing services on a cost-reimbursable basis.
  • USDA Forest Service, Pacific Southwest Region, Forest Health Protection (FHP), Forest Pests provides assistance in pest and pathogen identification.
  • USEPA and USDA, Spray Drift Task Force, developed AgDRIFT, a new model, to provide estimates of spray drift deposition under different pesticide application and meteorological conditions.
  • USEPA, Watershed Academy Web: Forestry Best Management is a forestry management module, with a series of interactive fact sheets on forestry management practices.


Meghan, W.F. 1980. Nonpoint source pollution from forestry activities in the Western United States: Results of recent research and research needs. In U.S. Forestry and Water Quality: What Course in the 80s? Proceedings of the Water Pollution Control Federation Seminar, Richmond, VA, June 19, 1980, pp. 92-151.

Norris, L.A., H.W. Lorz, and S.V. Gregory. 1991. Forest Chemicals. Influences of Forest and Rangeland Management on Salmonid Fishes and Their Habitats. American Fisheries Society Special Publication 19, pp. 207-296.

Riekerk, H., D.G. Neary, and W.J. Swank. 1989. The magnitude of upland silviculture nonpoint source pollution in the South. In Proceedings of the Symposium: Forested Wetlands of the Southern United States, July 12-14, Orlando, FL, pp. 8-18.

USEPA. 2002. National Management Measures to Control Nonpoint Source Pollution from Forestry. Pre-Final Draft. U.S. Environmental Protection Agency, Office of Water, Washington, DC.

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