Chemical control of curled dock (Rumex crispus L.) and other weeds in noncropped areas

Abstract

Rumex crispus L. is an invasive species widespread in our country and in particular in the region of North Bulgaria. It is characterized by high biological and ecological plasticity. Owing to its great reproductive potential, the weed has been assigned to the list of economically most important weeds in the country. With the purpose of studying the possibility of chemical weed control in noncropped areas with heavy natural background infestation with R. crispus L. and other dicotyledonous weeds, two field trials were carried out. A ready-to-use herbicide mixture 2,4-D 140.2 g/l-1 + Triclopyr 144 g/l-1, trade product Genoxon 3X (X0050), was tested at two doses of active ingredient, 3552 and 2842 ml/ha-1. It was found that: (1) population density of Rumex crispus L. can be successfully reduced by treatment at the stage of early stem formation; herbicide efficacy with 3552 and 2882 ml/ha-1 doses on the 21st day after treatment was 100% and 90.5%, respectively, at the end of vegetation 94.4 and 85.7%, respectively; (2) herbicidal efficacy was lower when R. crispus L. was treated at the 5 - 6 leaf stage, being 100 - 94.1% and 80 - 76.5% respectively for the indicated doses and time of recording; (3) at the studied doses the herbicide controlled both annual dicotyledonous weeds (Amaranthus spp., Chenopodium album L., Portulaca oleracea L.) and perennial dicotyledonous ones (Cirsium arvense L., Sonchus arvensis L., Convolvulus arvensis L., Carduus acanthoides L.), but it was not toxic to monocotyledonous weeds.