A simple model of crop loss by weed competition from early observations on relative leaf area of the weeds.
A new simple empirical model for early prediction of crop losses by weed competition was introduced. This model relates yield loss to relative leaf area of the weeds shortly after crop emergence using the relative damage coeff. q as the single model parameter. This model is derived from the hyperbolic yield density relationship and therefore accounts for the effects of weed density. It is shown that the model also accounts for the effect of different relative times of weed emergence. A strong advantage of the approach is that it can be used when weeds emerge in separate flushes. The regression model described experimental data on sugarbeet-lambsquarters (Chenopodium album) and maize-barnyard grass (Echinochloa crus-galli) competition precisely. The model describes a single relationship between crop yield over a wide range of weed densities and relative times of weed emergence. Possibilities for scientific and practical application of the model are discussed.