Fish mortality following application of phenthoate to Florida citrus [Insecticides]

Field experiments were conducted, reproducing normal spray conditions in a Florida citrus grove, to assess the toxicity of the pesticide phenthoate to fish. Caged fish were placed in a treatment pond, close to the spray area, and in a control pond. Drift pads were used to determine airborne contamination. Pond conditions and experimental results are tabulated. No change in conditions or fish mortality was noted in the control pond, while in the treatment pond almost all the fish died within 8 days and significant mortality of gastropods and aquatic insects was observed. The concentration of phenthoate in the treatment pond 24 hours after spraying was 21.8 ppb.