The Swedish Environmental Protection Agency has drawn up general guidelines (97:3) and regulations (SNFS 1997:2) on the safe application of plant protection products.
Sweden has developed 2 "Helpers", these can be used to determine a suitable safety distance. These helpers have been developed by the Swedish Environmental Protection Agency and the Swedish University of Agricultural Sciences (SLU) and are issued by the information and training campaign ”Greppa växtskyddet” (Focus on Plant Protection).
In the tables contained in the helpers it is possible to obtain a measure of the minimum distance to be kept from the field boundary or from sensitive areas, for example adjoining watercourses.
Knowledge of air temperature, wind speed and sprayer setting is needed to use the helpers.
There is a general requirement in Sweden for all professional users of plant protection products to calculate and observe proper spray drift related safety distances based on local conditions. A particular Helper (Hjälpreda in Swedish) has been developed to facilitate this exercise for farmers at each spraying occasion. A Helper has also been set up for orchards (document). The objective is to mitigate spray drift in order to protect vulnerable terrestrial and aquatic compartments outside the field and in particular aquatic organisms, non-target invertebrates and plants. Users first need to measure wind direction, wind speed and temperature and together with data on dose rate, boom height, droplet size (nozzle type) they can calculate the proper safety distances needed taking into account of the sensible off-field objects being present at each spraying occasion.
These requirements are established in a national regulation issued by the Swedish EPA and can also be lay down in the authorization provisions for certain plant protection products. The EPA regulation is from 1997, but will now be revised in order to implement some elements of the Sustainable Use Directive 2009/128/EC. In addition to the general requirement to calculate and take account of spray drift there is also a requirement to use well calibrated equipment to be able to measure the local wind and temperature. For this purpose a thermometer, a wind gauge and a wind vane is required.
The Helper is based on the following input parameters:
Temperature: 10, 15 or 20°C
Wind speed at 2 m height: 1.5, 3 or 4.5 m/s
Dose rate: 1/4, 1/2 or full dose
Spray boom height: 25, 40 or 60 cm
Spray droplet size: Fine, Medium or Coarse
Use of particular spray drift reducing techniques: 50, 75 or 90% reduction
There is also a need to decide whether to apply general or special concern with regard to sensible off-field objects:
The Helper was originally developed by the Swedish EPA and the Swedish University of Agricultural Sciences and has been in use since 1997. Although based on a legal requirement, the Helper also forms a part of a voluntary information campaign between authorities, farmer organisation and industry called Focus on Pesticide (Säkert Växtskydd). The Helper is intended for field use with tractor mounted boom sprayers. It is limited to spray drift and covers options to mitigate risk for sensitive Rea such as surface waters, non-target organisms.
A similar Helper was developed in 2008 for spraying in orchards. It is based on the similar principles for spray drift but does instead pay regard to the specific airblast techniques used in orchards. In this Helper, two different approaches are used, one before and one after flowering. The wind speed is measured at 1 m above the fruit trees, a 20 m spray width is assumed but the air temperature is disregarded. Depending on the equipment used a 25, 50, 75, 90 or 99% drift reduction is possible (Nilsson J, et al. 2006).
Source: Mitigating spray drift in Sweden. 2014. Säkert Växtskydd