Weeds represent one of the limiting fac­tors for reaching high grain yields in maize pro­duction. Observation of weed species emergence, as well as proper choice of herbicides and term of their application, can significantly decrease nega­tive effects to maize crops caused by weeds. So the aim of this paper was to explore the effect of weed killers, applied after sowing but before sprouting, on decrease of weed species presence and weed plants number in maize crops. The field trial car­ried out during 2005 in the vicinity of Leskovac (southern Serbia) was set to observe efficiency of four herbicides (S-metolachlor, acetochlor, alach­lor + linuron, and alachlor), applied after sow­ing but before sprouting, in preventing weeds of maize crops. The trial was set in RCB design with three replications. Number of weed species and plants was counted per m 2 , and efficiency coefficient of herbicides was calculated according to Dodell et al. (Stanković, 1969). There were seven weed spe­cies in the maize crop with the average number of individuals per m 2 of 123. The highest number of individuals was shown by Se­taria ssp. (42 plants/m 2 ) and Chenopodium album (35 plants/m 2 ). The highest coefficient of weed killing efficiency was given by acetochlor and amo­unted 71.54, and the low­est one by s-metolachlor where it was 63.41. All these weed killers expressed a weak effect to Abutilon theophrasti, Convolvulus arvensis, and Sorghum halepense. All the herbi­cides had a highly significant effect on grain yield value. Maize grain yield ranged between 7.235-8.943 kg/ha.

herbicides; weeds; maize; coefficient of efficiency; grain yield

Presentation: oral