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Drift values

Trial for assessing drift values

During spraying plant protection products can drift to non-target areas. Drift cannot be avoided completely but has to be minimized to prevent pollution of the natural environment. This can be achieved by several technical approaches like special nozzle techniques or novel plant protection equipments, which are advanced continuously. Based on an extensive amount of data the JKI defined basic drift values. New application techniques can be compared and valued with the help of drift values.

During the approval procedure for plant protection products, drift values (published 1995, Studies on the spray drift of plant protection products, Mitteilungen aus der Biologischen Bundesanstalt für Land- und Forstwirtschaft, Heft 305) help to evaluate effects on non-target organisms and determine use ordinances.

The basic drift values are based on 199 drift trails conducted between 1989 and 1992. The drift values are the 95th percentile rounded to one decimal place.

Additionally further trials in arable farming and fruit-growing were conducted between 1996 and 1999 with an enhanced technique of measurement. It allowed the safe determination of measurement values 10 times lower than before. Hence less than 0.01% of the application rate became measurable in soil sediments. Thereupon the JKI extended the measurement distances in the field trails up to 100 m from the treated area, leading to more reliable conclusions concerning the drift curve.

Overall, results of 50 field trials in arable farming and 72 field trials in fruit-growing are available as basis for comparison. New field trials in viticulture show that a distinction between early and late growing stages is not necessary. German authorities involved in the authorization of plant protection products agreed to  use the 90th percentile instead of the 95th, following the procedure defined by the FOCUS group (Surface Water Scenario Group).

Basic drift values for fruit-growing were determined distinctly for early and late growing stages. Because of different leaf density, drift varies strongly between growing stages.

Additional drift values apply for special uses like house and garden plots, railway tracks and field crops treated with rates of water above 900 l/ha.

All drift values are published in the federal bulletin (in German: Bundesanzeiger). Here you will find all drift values, if you click the link "Deutsch"  to our German website, then see "Abdrifteckwerte" at the bottom of page.