Nature of exposure is a fundamental driver in nontarget terrestrial plant risk assessment for pesticides; consequently a novel study was designed to generate field-based drift exposure and evaluate corresponding biological effects of the herbicide mesotrione. The approach used a combination of US guideline drift reduction technology and vegetative vigor approaches. In each of 3 independent replicate spray application trials, 10 pots each of lettuce and tomato were placed at distances of 10, 20, 30, 40, and 50 ft (∼3, 6, 9, 12, and 15 m) from the downwind edge of the spray boom. Each application was conducted using a commercial 60-ft (18-m) boom sprayer fitted with TeeJet Technologies TTI110025 nozzles, with a nominal application rate of 0.2 lb a.i./A (224 g a.i./ha). The environmental conditions required by the protocol (air temperature 10-30 °C and wind perpendicular to the swath (±30°) blowing toward the plants at a mean wind speed of ≥10 mph [≥4.5 m/s] measured at 2.0 m above the ground) were met for each application. Following exposure, plants were transferred to a greenhouse for the 21-d vegetative vigor phase of the study. Symptoms of phytotoxicity and plant height were assessed at 7, 14, and 21 d after treatment. On completion of the 21-d after treatment assessment, all plants were harvested and dried in an oven to determine shoot dry weight. The biological data indicated that no statistically significant effects were observed at a distance of 30 ft (∼9 m) from mesotrione drift at wind speeds of ≥10 mph (10.9-12.4 mph); this endpoint (30 ft) is defined as the no observed effects distance (NOED). Environ Toxicol Chem 2017;36:2465-2475. © 2017 SETAC.
In 2009, the European Union adopted the Directive on Sustainable Use of pesticides (SUD, Directive 2009/128/EC) establishing a framework for achieving a sustainable use of Plant Protection Products (PPPs) through reducing the risks and impacts of PPP use on human health and the environment, promoting integrated pest management and stimulating effective non-chemical alternatives. The core idea of the SUD is that it is necessary to monitor the use of PPPs through the implementation of an appropriate set of risk indicators to monitor progress and trends in risk reduction within the Member States. To contribute to this direction, following a comprehensive analysis of the risk (including procedures of risk assessment and risk management) and involving stakeholders in the decision process, specific toolboxes of practical indirect risk indicators of exposure of Operators, Workers, Bystanders and Residents were developed and are now available to be used by Member States (MSs) based on their specific context.
We determined the dermal exposure of plant protection products containing prothioconazole (PTZ) after spraying a standard crop using a tractor‐operated boom sprayer. Dermal exposure of adult and child bystanders to PTZ and its metabolite, PTZ‐desthio was quantified in bystander drift studies. Exposure was greater on mannequins placed 2 m from the zero line, compared with 5 m or 8 m. When the overall boom height above the ground was the same, the relative boom and canopy heights had no impact on the spray drift, allowing pooling of data from different studies. Wind tunnel experiments were used to compare two flat fan nozzle types, which allowed dermal exposure measured in early bystander field studies using the flat fan TeeJet XR 110 03 nozzle to be adjusted using a conversion factor to reflect exposure from Hypro F110‐03 nozzles. Values from studies using both flat fan nozzle types were pooled and compared with exposure using drift reduction nozzles. For the first time, 3D life‐size mannequins used in field studies have shown that drift reduction nozzles exceed the EFSA‐recommended 50% reduction in drift (potential exposure was reduced by 58–67%). The BREAM2 (Bystander and Resident Exposure Assessment Model) model resulted in better predictions of measured dermal exposure of PTZ equivalents than BREAM, albeit producing more conservative values for the 75th and 95th percentiles of potential dermal exposure compared to field studies (2.6‐fold higher than measured values). Our results using measured potential and actual exposures indicate that the EFSA calculation of 18% protection by light clothing was too conservative.
The fundamental principles of good application are the same whether a biopesticide or chemical pesticide is being used. However, there is a view that biopesticides are more sensitive to application. A good application technique should result in the minimum amount of biopesticide being used, which requires that the dose is delivered to the right location at the right time and in the right form. This chapter discusses the factors that are important in achieving this. The chapter concludes that calibration is important and automation should bring benefits. The biopesticide mode of action, the pest or disease and the crop structure are important to understand. Without this, growers will continue to try to visibly cover every part of the plant with spray resulting in high levels of waste and poorer control than optimum. More research on the interaction between performance and application is needed to enable the principles of IPM to be implemented.
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