Valsorda, Gualdo Tadino - Viola eugeniae Parl.
Evolution of weed flora and vegetation of the most important crops in Italy. Weed communities, which are normally found in the crops, are dynamic entities in rapid evolution, regarding to the adopted agronomic technique. The influence of the new agronomic techniques on weed flora evolution, both on winter-spring and summer crops, have been examined. In particular the influence of chemical weed control, crop rotation, new sowing techniques, nitrogen fertilisation, the choice of varieties and the management of abandoned lands have been considered. As consequence the original weeds communities are changed and it is becoming much more difficult to fit them into the traditional phytosociological schemes.
agronomic techniques, weed communities, weeds