Effect of nicosulfuron on plant traits of Xanthium strumarium

Field experiments were conducted in 2008 and 2009 at the Experimental Field Institute Padinska Skela PKB Agroekonomik, near Belgrade, to quantify effects of nicosulfuron on plant traits (vegetative production and fecundity) of Xanthium strumarium. Plants of X. strumarium were grown in monoculture on plots of 5 x 4.2 m. Inter-row spacing was 24 cm and the distance between the rows was 70 cm. Plants were treated with nicosulfuron when they developed two pairs of leaves. The applied rates of nicosulfuron were 20, 40 and 80 g a.i. ha(-1) and one control treatment (without herbicide application) was included. Vegetative parameters (height, fresh weight, leaf area and leaf area index (LAI)) were recorded just before herbicide application and four times after the herbicide treatment. Measurements were made at intervals of about two weeks. At maturity, fecundity of weeds (bur weight plant(-1) and bur number plant(-1)) was measured. In both years, the application of nicosulfuron caused less growth (height, fresh weight and LAI) of X. strumarium in comparison with the control. All rates of nicosulfuron reduced vegetative parameters, which decreased as rates of nicosulfuron increased. On the other hand, effects of nicosulfuron on bur production were not equivalent to its effects on vegetative parameters. Only the highest rate of nicosulfuron reduced bur production significantly