Best Management Practices For Mitigating Pesticides In Runoff From Vegetable Systems In California

Commercially produced vegetables in California utilize a variety of pesticides to prevent losses from insects, diseases, and weeds. Several classes of these chemicals have been shown to impair water quality in receiving water bodies by causing toxicity and impacts to resident benthic macroinvertebrate communities. Common pesticide compounds have a wide range of solubilities and can vary greatly in how long they persist in the environment. Toxicity tests using a variety of aquatic organisms and field assessments of in-stream invertebrate populations demonstrate the potential for acute and chronic pesticide impacts in receiving waters. State and local regulators have encouraged growers to reduce the amount pesticides in runoff through source control and the installation of on-farm management practices that treat runoff. This chapter introduces strategies for source control and summarizes the most common types of on-farm management practices. Treatment practices are roughly grouped by their ability to remove hydrophobic and soluble compounds from agricultural runoff and can be further characterized by the main mitigation strategies: infiltration, degradation, sorption, and sedimentation. Integrated approaches show the most promise for maximizing reduction of pesticide loading and associated toxicity to aquatic organisms.