18.104.22.168.2. Setup of field trials using other devices for a direct dust application
A few testing facilities have developed machinery for a direct application of dusts in field trials. As only small amounts of contaminated dust containing insecticides are emitted during sowing operations, only very small amounts of these dusts have to be applied homogenously. To ensure a good dispersion of small amounts of insecticidal dusts during application in the field, an inert filling material may be necessary. Different materials may be used for filling purposes. Small dust particles of soil seem to represent real field situations best and are recommended. A good mixing of the contaminated dust and the filling material needs to be ensured. It is important to ensure that appropriate particle sizes of dusts and of the filling material are used. In semi-field trials with manual application of dusts on flowering crops, it has been demonstrated that smaller particles, e.g. below 160 µm, result in higher effects. Small particles are also more likely to drift into adjacent crops. See section 22.214.171.124.2.4. of the present manuscript for the method.