Postemergence weed control in seedling alfalfa (Medicago sativa L.) with imazamox

Field trails was conducted during 2005 and 2006 in two localities. The objective of the study was to evaluate the suitability of imazamox to provide selective control of weeds in seedling alfalfa. The imazamox selectivity and influence on alfalfa dry matter yield were also evaluated. Weed population in the trials was composed of 17 and 21 weed species in Skopje and St. Nikole region, respectively. The most prevailing weeds in both region were: Sorghum halepense, Setaria verticillata, Veronica hederifolia, Chenopodium album, Alopecurus mysuroides, and Datura stramonium. Total weediness in Skopje region was 340, 6 plants m-2, and in St. Nikole region 62, 2 plants per 1 m-2. Imazamox at 1 L ha-1 and 1.2 L ha-1 applied at the 3-4 trifoliate stage showed high selectivity and herbicidal efficacy reaching 96.2-99.0% in both regions. Herbicidal treatments in both regions significantly increased alfalfa dry matter yield in comparison with the weedy check.