Cross herbicide resistance to tribenuron-methyl and imidazolinones in sunflower

Herbicide cross-resistance studies were conducted in the field in 2021 and 2022. We studied the Surus hybrid and the large-seeded cultivar Consul, homozy-gous for the gene of resistance to tribenuron-methyl Sur, as well as the large-seeded cultivar Aladdin, ho-mozygous for the gene of resistance to imidazoli-nones Imr. The large-seeded cultivar Caravan was the standard for herbicide susceptibility. Herbicides Ex-press (tribenuron-methyl) and Euro-Lightning (imazamox, imazapyr) were used. Plants were treated with herbicide in the phase of three pairs of leaves using a backpack sprayer. The degree of plant damage was assessed on the 10th day after treatment using a 9-point scale of phytotoxicity. The presence of susceptible, but not dead plants with leaf morphoses, in an amount of up to 16% when treated with Euro-Lightning sulfonylurea-resistant hybrid Surus and variety Consul indicates their partial cross-resistance to imidazolinones. The presence of susceptible, but not dead plants with leaf morphoses, in an amount of up to 35%, when the imidazolinone-resistant cultivar Aladdin is treated with Express indicates its partial cross-resistance to tribenuron-methyl. Morphological anomalies in the growth and development of susceptible but not dead plants, which are intermediate points of 4-6 on the phytotoxicity scale, make biologically surviving plants unpromising from a breeding point of view.