This study, realized on a network of pilot farms animated by AGRIDEA in the French part of Switzerland and in Ticino aims to provide global information about the evolution of phytosanitary practices in arable crops. The assessment of practices focusses on the number of interventions in each crop, the number of applications and the quantity of active substance per hectare. Three periods are compared : 1992 to 1994, 1997 to 1999 and 2002 to 2004. The number of interventions varies mainly according to the crop. A potatoes plot is on average treated 8 times and sugar beets need on average 4 to 5 runs. Cereals cultivated in “PER” mode and rape are treated between 2 and 3.5 times. The intervention number is less than 1.6 for corn grain crop and autumn cereals “extenso”. Half of active substances are herbicides and over a quarter, fungicides. The evolution of active substances show that their number decreases by 13 %; 57 % of the substances are present during all the considered period and, in 2002 - 2004, 35 % are new molecules which didn’t exist in 1992 - 1994.