Effects of different periods (0-14-28-42-56-70-84 and 98 days) of weed control in peanut plants (Arachis hypogaea L.) were studied in Moji-Guaçu region (State of São Paulo). The main weed species in the experimental area were: Acanthospermum australe (Loef.) O. Kuntz, Waltheria indica L.; Borreria alata D.C.; Richardia scabra L.; Rhynchelytrum repens (Ness) Stapf. et Hubb and Diodia teres Walt. During the whole peanut life cycle, except at harvest time, the most important weed species was A. australe. The initial period of weed control decreased the density of the weed community, as well as the number of species and modified the relative importance of populations. After 42 days the weed competition had affected the peanut development by reducing plant growth, leaf area, leaf area index and epigeal storage of dry matter. The number of twigs and of leaflets per plant, and the quality and vigour of seeds were not affected. The peanut pod productivity decreased 31,5% in the presence of weeds. The total period avoiding interference in the production was 14 days and the period before the interference was 70 days.
phytomass; production components; growth assessment; germination