Designing a model to investigate cropping systems aiming to control both parasitic plants and weeds

Branched broomrape (Phelipanche ramosa (L.) Pomel) is a parasitic plant, which causes severe yield losses in major crops worldwide. Because of its broad host range, including numerous non-parasitic weed species, the persistence of its seeds in the soil, and the poor efficiency of available management techniques, broomrape management is complex. The objective of the present paper was to develop a broomrape-dynamics model to support the design of management strategies combining multiple techniques aiming at long-term control of broomrape. Towards this goal, we developed a simulation model with formalisms and parameters based on data from our own experiments and the literature. This model called PHERASYS combines 1) a demographic submodel to predict broomrape seed bank dynamics, 2) a trophic-relationships submodel to predict the effect of parasitism on crops and weeds, and 3) a submodel of weed dynamics in agroecosystems to predict the growth of crops and weeds from cropping techniques and pedoclimate. Thanks to an individual representation of each host plant, PHERASYS is able to simulate complex heterogeneous canopies. This model can be used as a tool to test management strategies including crop mixtures and relying on biological regulations by weeds.