Weed control in sunflower fields by clearfiled technology
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Author: Anyo Mitkov, Mariyan Yanev, Tonyo Tonev, Miroslav Tityanov
Three block design field experiments were carried out in the period 2012 – 2015, following the same methods, on three different sites in the country, which differ significantly in the spectrum of the available weeds. The subject of the experiments was the improved version of the Clearfield Plus technology. In all the three years the sunflower hybrid ES Candimis CL Plus was planted on the three sites. The major aim of the experiments on the three sites was to establish the selectivity for sunflower and the efficacy of Pulsar 40 (40 g/l imazamox) against almost all the economically important weeds in that crop. The reported phytotoxicity caused to sunflower on the three sites in the three years was expressed in a slight discoloration of the treated sunflower plants, which was totally overcome between the 14th and 20th day. The results of the experiments show that the greatest differences in the efficacy of Pulsar 40 were reported about its activity against perennial weed species. When Pulsar 40 was applied separately without DASH, its efficacy against Johnson grass, corn thistle, field bindweed, hemp agrimony, rough cocklebur, white goosefoot, purslane and broomrape was significantly reduced. Referring to its efficacy against the annual broad-leaved weed species redroot pigweed, charlock mustard, wild radish, clea-vers, black nightshade, etc., it was 100% and no differences were observed between the rates of 80, 100 and 125 ml/da. The separate use of the herbicide at a rate of 125 ml/da shows the same efficacy against more stubborn weeds, as that of Pulsar applied at the rate of 80 ml/da together with 80 ml/da of the adjuvant DASH.

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