Analisi di sensibilità al glifosate in Lolium spp.

The availability of a reliable and realistic baseline sensitivity is critical to discriminate between susceptible and resistant populations. This study documents the susceptibility of 30 Italian populations of Lolium spp., environments, towards glyphosate. Sampling sites included field margins, organic farms (winter cereals), conventional farms (winter cereals, sunflower and perennial crops) and roadsides. Sampling sites cover all major Italian agricultural areas and have been chosen according to the absence or scarce application of glyphosate during the last decade. Therefore, the data do not show the status of truly unexposed populations, but they rather represent the "real" susceptibility status of Italian Lolium spp. to glyphosate in agricultural environments. A first outdoor dose-response pot experiment was conducted during spring 2012 and a second one during autumn of the same year to assess the variability of ED50, ED90 and slopes of the fitted non-linear curves. In the first experiment ED50 vary from 155±5.9 to 260±6.7 while ED90 from 243±20.8 to 506±79.1 g a.e./ha. During the autumn experiment ED50 vary from 107±10,1 to 308±8,9 while ED90 from 269±49,5 to 410±23,4 g a.e./ha. From this study it has been outlined that the dose of 360 g a.e./ha, used in the past for the control of Lolium spp., it is not sufficient anymore. Survival data indicates a complete control of susceptible populations using glyphosate at 540 g a.e./ha. From these data we suggest the adoption of a dose at least of 700 g a.e./ha of glyphosate for field applications.