Modelling the population dynamic and management of Bromus diandrus in a non-tillage system

A cohort-based population model was developed to simulate the population dynamics and management of Bromus diandrus. Model parameters were derived from our experiments and from published sources. Individual and integrated management strategies were simulated. More than 85% of B. diandrus seeds emerged within the first cohort. In the absence of any control the seed-bank population grew until reaching an equilibrium at density of 17,324 seeds m−2. Results pointed to the difficulty in controlling this weed with individual control tactics. All integrated programmes simulated resulted in long-term reductions in the seed bank. Simulations showed that the combination of pre-emergence and post-emergence herbicides or combination of autumn shallow cultivation and post-emergence herbicides are the best techniques to employ in integrated weed management (IWM) programmes in cereal. A sensitivity analysis indicated that B. diandrus is particularly vulnerable to small changes in the fecundity of the first cohort. Consequently, it is important to find strategies which can reduce the effect of the first cohort, because this is a clue to the control of this weed.

► The demography and population dynamics of Bromus diandrus was modelled.
► We estimated the annual life history vital rates of B. diandrus.
►  We identify conditions under which reducing the weed seed bank is an important goal.
► The fecundity of the first cohort is a clue to the control of B. diandrus.