In field crops, the systems which integrate plant cover into intercropping under the weather conditions of the south-east of France have to adapt their crop strategies. During the 'transitional period' the crop strategies are adapted from the harvest of the previous crop until the establishment of the spring crop. The effects of plant cover on the density of emerging plants from the spring crop are related to the weather conditions of the year, soil maintenance tillage in spring, seed quality, risk of slugs and types of covers. It is necessary to take preventive measures (choice of species, cover density, cover destruction date, 5.