Efficacy and selectivity of some herbicides on winter oilseed rape

M. Dimitrova*, I. Zhalnov, D. Stoychev

Department of Farming and Herbology, Faculty of Agronomy, Agricultural University, 12 Mendeleev, 4000 Plovdiv, Bulgaria

Abstract. Within the period 2011 – 2014 in the experimental field of the Agricultural University, Plovdiv, field experiments were conducted using the herbicides Teridox (500 g/1 dimetochor), Butizan S (500 g/1 metazachlor), which were applied to the soil after planting the crops and before their germination, and also Modaon 4F (48 g/1 bifenox) and Butizan S, which was applied to the leaves during the vegetation period of the rape. The experiments were made using the block method over an area of 25 m2 in four repetitions. It has been established that the herbicides demonstrate excellent selectivity for this crop, which was measured on the EWRS scale in marks and control the existing annual types: Amaranthus retroflexus L., Portulaca oleraceae L., Chenopodium album L., Solanum nigrum L., Setaria spp., Stellaria media L. and self seeded wheat plants. The weeds in the control sample without herbicides have very high density and on the 40th day after treatment their number reaches 123 plants/m2. On average for the period of the survey (2011 – 2014), the efficiency of the applied preparations Teridox, Butizan S and Modaon 4F on the 20th day after treatment ranges from 70.5% to 79.4% for the soil herbicides and from 72.8% for 76.9% for the leaf herbicides. This dependence is preserved to the 45th day after treatment.

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