Influence of the spraying system on fungicides distribution on wheat plants

Three trials were carried out during springs 2003 and 2004 to compare the distribution of fungicides on the different leaf layers of wheat plants. Mixtures of 1 L/ha of Amistar (SC, 250 g/L of azoxystrobin) and 1 L/ha of Opus (SC, 125 g/L of epoxiconazol) were applied using two experimental sprayers carried by hand and three farmer's sprayers (including a Hardi TwinFlow one). Working pressure, speed, boom length, nozzles, volume of mixture per hectare were specific to each material. One to six days after the treatments, leaf samples were collected at each canopy level and the amount of both active ingredients was determined using gas chromatography with electron capture detection (GC-ECD). The distribution pattern of the fungicides on the different leaf layers was not affected by the spraying system. In the same way, neither the used equipments, nor the mixture volume per hectare, nor the air flow of the Hardi TwinFlow sprayer did not significantly influence the distribution of fungicide.