Geographical distribution of principal cereal weeds in setif high plains.

The invasion of the wheat and barley cultures by weeds remains among the major problems of agriculture in Algeria considering the importance of yield tosses caused by these species. The cereal yields average is less than 700 kg ha(-1). The main purpose of this work was to obtain informations on geographical distribution of principal cereal weeds in the setif high plains. Two bioclimatic areas may be distinguished in this region, the semi-arid in the south and the sub-humid in the north. One hundred ten fields of cereals were surveyed by stratified sampling. In each field the level of infestation was scored on a homogeneous surface. The weediness of the species was estimated on the basis of the frequency and average of abundance. The results indicate thirty four important species. This harmful flora was characterized by the prevalence of annual and brod leaved weeds. The study of the geographical distribution cards of these species shows three groups: species related to the northern zone, species related to the southern zone and species common to both zone. The knowledge of the geographical distribution of principal weeds is an essential element for any plan of integrated weed management.