Modellversuch zur Beschreibung von Konkurrenzvorgängen zwischen Sommerweizen und einer aus Capsella bursa‐pastoris L., Stellaria media L. und Alopecurus myosuroides Huds. bestehenden Mischverunkrautung

Investigation to Describe the Competition between Spring Wheat and a Weed Population Consisting of Capsella bursa‐pastoris L., Stellaria media L. and Alopecurus myosuroides Huds. When controlling weeds in cereals using economic threshold as criteria, weed populations must be evaluated for their potential to cause damage at a very early stage. As well as information of actual weed density or weed ground cover, further knowledge about the species specific growth and competition between weed populations is important. For this purpose the growth and competition between the weeds Capsella bursa‐pastoris L., Stellaria media L., Alopecurus myosuroides Huds. and spring wheat ( Triticum aestivum L.) as a model of a typical weed mixture in cereals were studied in a container experiment. The growth with time of individual species was documented using true colour image processing. In that these measurements are non‐invasive, the system lends itself specially to time‐dependent analyses. The increasing amount of ground covered by leaves between two observation times served as a parameter to evaluate the increase in biomass over this time period and could be used as a evaluation of the competitiveness of the weed species studied. The results can be summarized as follows: 1) Stellaria media L. proved to be the most competitive of the studied species. 2) The competition to spring wheat from each weed species was similar. 3) A multi species weed population had a tendenci to a lower competitiveness to spring wheat, than a weed population of only‐one species. The importance of this and other similar studies for the improvement for the prediction of economic weed thresholds to estimate weed populations in early stages will be indicated.