There is an increasing concern about excessive use of herbicides for weed control in arable lands. Usually the whole field is sprayed uniformly, while the distribution of weeds often is non-uniform. Often there are spots in a field where weed pressure is very low and has no significant effect on crop yield. The excessive use of spraying can potentially be reduced by spraying only those parts of the field where it has economic importance.

The competition relation between weeds and crop was ana-lyzed in context of real time patch spray. A non-destructive image analysis method was developed to estimate infestation of weeds at early growth stage. The image analysis method was further developed to estimate colour response of applying increasing doses of herbicides in selectivity experiments and to evaluate the weed-suppressing effect of mulches.