Increasing efficiency of irrigation may help to increase agricultural production without increasing the amount of irrigation water used. Better use of the rainfall in irrigation management strategy is one possibility, by using rain forecast and thus saving irrigation water. We developed specific anticipatory behaviour rules in the biodecisional model MODERATO to test this assumption. Simulations were done with different forecasting windows, amounts of expected rainfall and waiting days. Results show that the benefits (in term of margin) of using such anticipatory behaviour depend on the irrigation flow rate available, but are almost negligible. Due to this small benefit, a disruption of the irrigation management plan to account for the weather forecast does not seem worthwhile.