Efficacy of reduced doses of herbicide Callisto 480 SC + Atplus 463 and Basagran super on redroot pigweed (Amaranthus retroflexus)

As far as the field of weed control is concerned, there is a possibility to use methods based on mea­su­re­ments of chlorophyll fluorescence or reflectance of impacting radiation. The application of these methods can contribute to a decrease in the amount of applied pesticides so that it is possible to the reduce costs associated with their purchasing on the one hand and to control risks of environmental damage on the other. Within the period of 2005–2007, a small-plot experiment with grain maize was established and carried out in the Field Experimental Station of Mendel University of Agriculture and Forestry in Žabčice. The experimental doses of the herbicides CALLISTO 480 SC + ATPLUS 463 and BASAGRAN SUPER were 0.25; 0.1875 and 0.125 l ha−1 and 2.0; 1.5 and 1.0 l ha−1, respectively. The efficiency of herbicides and their killing effect on Amaranthus retroflexus were estimated by means of the apparatus PS1 Meter, which is capable to measure the percentage of damage of the photosynthetic apparatus of plants. The differences among doses of herbicide BASAGRAN SUPER were not statistically significant. These results showed that all doses were enough efficient against redroot pigweed. Statistically significant difference was found by herbicide CALLISTO 480 SC + ATPLUS 463, between dose 0.25 l ha−1 and 0.125 l ha−1. It was found out that the most suitable term for herbicide efficacy estimation of BASAGRAN SUPER by means of PS1 apparatus is the second day after its application and fourth day after the application for herbicide CALLISTO 480 SC + ATPLUS 463.