G. Delchev1*, T. Barakova2

1Department of Plant Production, Faculty of Agriculture, Trakia University, 6000 Stara Zagora, Bulgaria 2Field Crops Institute, 6200 Chirpan, Bulgaria

(Manuscript received 16 May 2016; accepted for publication 9 August 2016)

Abstract. The research was conducted during 2012 – 2014 on pellic vertisol soil type. Under investigation was cycloxydim tolerant maize hybrid Ultrafox duo (Zea mays L.). Factor A included the years of investigation. Factor B included no treated check and 3 soil-applied herbicides – Adengo 465 SC (isoxaflutol + tiencarbazon) – 440 ml/ha, Wing P (pendimethalin + dimethenamid) – 4 l/ha and Lumax 538 SC (S-metolachlor + terbuthylazine + mesotrione) – 4 l/ha. Factor C included no treated check and 5 foliar-applied herbicides – Stellar 210 SL (topramezon + dicamba) – 1 l/ha, Principal plus (nicosulfuron + rimsulfuron + dicamba) – 380 g/ha, Ventum WG (foramsulfuron + iodosulfuron) – 150 g/ha, Monsun active OD (foramsulfuron + tiencarbazon) – 1.5 l/ha and Laudis OD (tembotrione) – 2 l/ha. In addition to these variants by conventional technology for maize growing one variant by Duo system technology is also included in the experiment. It includes soil-applied herbicide Merlin flex 480 SC (isoxaflutole) – 420 g/ha and tank mixture of antigraminaceous herbicide Focus ultra (cycloxydim) – 2 l/ha + antibroadleaved herbicide Kalam (tritosulfuron + dicamba) – 300 g/ha. It is found that herbicide combination of soil-applied herbicide Merlin flex with tank mixture Focus ultra + Kalam by Duo system technology leads to obtaining high grain yield. High yields of maize grain are also obtained by herbicide combinations Lumax + Principal plus, Lumax + Laudis and Wing + Principal plus. The most unstable are the non-treated check and single use of soil- applied herbicides Adengo, Wing and Lumax. Technologically the most valuable are herbicide combination Merlin flex + Focus ultra + Kalam by Duo system technology, followed by combinations of foliar-applied herbicides Principal plus and Laudis with soil-applied herbicides Adengo, Wing and Lumax by conventional technology. Single use of herbicides has low estimate due to must to combine soil-applied with foliar-applied herbicides for full control of weeds in maize crops