Selectivity and efficacy of Pulsar 40 (imazamox) applied at different doses in sorghum (Sorghum bicolor L.) under field conditions

Weed control is a critical factor for successful sorghum production, particularly during the early stages of crop development, when competition with weeds can significantly reduce growth and productivity. The present study aimed to evaluate the selectivity and biological efficacy of the herbicide Pulsar 40 (active ingredient: imazamox), applied at different doses, in sorghum (Sorghum bicolor L.), hybrid Sentinel IG. Field experiments were conducted during three consecutive growing seasons (2023–2025) under the agro-climatic conditions of South Central Bulgaria. Herbicide selectivity to the crop was assessed visually using the EWRS scale at 7, 14 and 21 days after treatment (DAT). Biological efficacy was evaluated against major annual and perennial weed species present in the experimental field. The results showed high selectivity of Pulsar 40 to sorghum at all tested doses, with only transient phytotoxic symptoms observed at the highest dose during 2023, which disappeared completely by 21 DAT. Herbicide efficacy varied among weed species and doses, with high control of annual broadleaf and grass weeds, while perennial species such as Sorghum halepense and Convolvulus arvensis were only partially controlled. The study confirms that Pulsar 40, when applied at recommended and moderately increased doses, provides effective weed control with good crop selectivity in sorghum.