Annual Reports

1997—Water Quality and IPM

Identifying Agricultural Management Practices to Reduce Pesticide Runoff

The Problem

The California State Water Resources Control Board and the Regional Water Quality Control Boards are charged with protecting the beneficial uses of California's surface waters. State staff from these agencies have been monitoring the Sacramento and San Joaquin rivers and the Delta for toxicity using bioassays since 1986, giving particular attention to the three U.S. Environmental Protection Agency indicator species (larval fish, zooplankton and algae). Mortality of the zooplankton species, Ceriodaphnia dubia, has been observed in water samples collected from agricultural and urban areas following winter rains. Organophosphate pesticides, which are commonly used as dormant sprays on several orchard crops, in-season on many other crops, and to control pests in the urban landscape, have been implicated.

Identifying a possible problem is just one part of the issue. Its resolution requires understanding the specific production practices or urban uses related to the problem and the mechanisms of off-site movement of pesticides, and then developing alternative practices to reduce pesticide runoff to a level that eliminates toxicity in surface waters.

The best solutions to these issues will be those that include input from the users of pesticides such as growers, landscape managers, urban and suburban residents, the agencies charged with maintaining water quality, and a solid information base. In the university, this requires the multidisciplinary interactions of environmental and agricultural scientists.

The Initiative

Project Director Frank Zalom is coordinating this new programmatic effort on behalf of UC IPM together with David Hinton, Director of the Aquatic Toxicology Laboratory of the School of Veterinary Medicine and representing the UC Davis Center for Ecological Health Research; and Donald Erman, Director of the DANR Centers for Water and Wildland Resources. Michael Oliver, who has had many years of experience with Veterinary Extension, will provide programmatic support. A steering committee consisting of state agencies, representatives of grower groups, and local Cooperative Extension staff is being formed to provide direction for the project. Funding is being provided initially through a contract from the State of California Water Resources Control Board which has been very supportive of this concept.

One of the initial tasks of the project is to provide detailed assessments of the current knowledge of alternative agricultural practices for reducing or eliminating pesticide use, particularly as it pertains to orchard crops and particularly as it pertains to the use of dormant sprays. These assessments would specifically address what is known about alternatives relative to

• what studies have been done,
• where and under what conditions were studies done,
• degree of insect control achieved by the practice, and
• economic practicality and implications of the practice.

The assessments would also review mechanisms of movement of target pesticides from orchards and fields into surface water, and conditions that favor or reduce such movement. The final assessment will highlight gaps in current information and identify research needs.

Along with this assessment, educational documents and workshops will be developed to focus on transfer of information, and study sites will hopefully be identified to evaluate efficacy of pest control and environmental impacts on surface waters through monitoring by agricultural and environmental scientists.

Future Goals

In the future, it is hoped that this initiative will become a model for integrating natural resource and pest management research, and that it can be used to address water quality problems from urban sources as well as tail water runoff from agricultural or other sources during the season. The model could also be used proactively in identifying potential impacts of proposed pest management practices, and to develop mitigation measures before the new practices become widely used or result in unforeseen environmental problems.

Of course, in order to accomplish these goals additional research efforts will be needed to improve environmental montoring as well as to identify alternative pest management approaches, probably including new pesticides and nonchemical approaches as well as mitigation measures. Unfortunately, research that permits integration of these diverse disciplinary areas is expensive, and funding opportunities for such efforts are limited. UC IPM, the Center for Ecological Health Research, and the Centers for Water and Wildland Resources will be working with agencies and other external groups to further develop this concept, hopefully to expand current efforts that are being conducted within each unit at this time.

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