Efficacy Against Broomrape and Selectivity of Imazamox-Containing Herbicides in Sunflower

Abstract

During the period of 2016-2017 a field trial for evaluating the efficacy of imazamox-containing herbicide products for control of sunflower broomrape (Orobanche cumana Wallr.) was conducted. The experiment was carried out in the experimental base of the department of ”Agriculture and Herbology” of the Agricultural University of Plovdiv, Bulgaria. The selectivity of the herbicides to the sunflower plants was also evaluated. The grown sunflower hybrid was „Lucia CLP”. Variants of the trial were: 1. Untreated control; 2. Pulsar® 40 - 1200 ml ha-1 ; 3. Pulsar® 40 - 2400 ml ha-1 ; 4. Pulsar® 40 - 1200 ml ha-1 ; 5. Pulsar® 40 - 2400 ml ha-1 ; 6. Pulsar® Plus - 2000 ml ha-1 ; 7. Pulsar® Plus - 4000 ml ha-1 ; 8. Pulsar® Plus - 2000 ml ha-1 ; 9. Pulsar® Plus - 4000 ml ha-1 . At variants 2, 3, 6 and 7 the herbicides were applied in phenophase 4th – 6th true leaf of the sunflower (BBCH 14-16), and at variants 4, 5, 8 and 9 – in phenophase 8th – 10th true leaf (BBCH 18-19). The highest efficacy against the broomrape was reported for the treatments of variants 4 and 9. For the control the highest broomrape density was reported – 13.65 specimens per 1 sunflower plant average for the period. It was observed that Pulsar® Plus was more selective to the sunflower hybrid in the study in comparison to Pulsar® 40. After the treatment with Pulsar® Plus at rate of 2000 ml ha-1 in phenophase 8th – 10th true leaf the highest sunflower seed yield was recorded. It was proven that the seed yield from the plants treated with doubled herbicide rates was lower from the plants treated with the registered rates. The untreated control had the lowest yield. A similar tendency for the indicators 1000 seeds weight and hectolitre seed mass was observed.