Over a period of 4 years a trial was carried out to determine the time when interference of weeds with plant production was highest. Water availability was considered to be 125 mm based on climatic water balance to estimate the soils water storability. The main weeds were Emilia sonchifolia, Digitaria horizontalis, Rynchelitrum roseum and Bidens pilosa. In period 1 (December to February) very little water is stored in the soil and there is a water deficit. In period 2 (March to May) a marked increase in water storage is observed; however with no plant availability and with a storage in March. Only in period 3 (June to August) occurrs a surplus of storage water. During period 4 (September to November) water availability in the soil decreases and the water deficit increases progressively. It is concluded that in this ecosystem orchards must be kept free of weeds from September/October to April/May.
Critical period; competition; citrus; Citrus sinensis