In the years 2000 - 2009 (10 years) was conducted weed survey on the farms in conventional farming system. The aim was to detected top 10 of the most harmful weeds, as important biotic stress factor, on the farms in the canopies of spring barley in all production  regions of the Slovak Republic. The actual weed infestation was evaluated by standard methods common used by a counting method per square. The four randomly established sample quadrants were situated minimally 20 m from field margin and apart each other, respectively. Three most dangerous weeds in spring barley stands in the maize production regions were: Cirsium arvense (L.) Scop , Elytrigia repens (L.) DESV and Avena fatua L. . In sugar beet production region it was Cirsium arvense (L.) Scop , Tripleurospermum perforatum (Mérat) M. Lainz and Anthemis spp.. In potato production region it was Chenopodium spp., Tripleurospermum perforatum (Mérat) M. Lainz and Anthemis spp .. Temporral dynamic of actual weed infestation depends on production region. In the last decade was detected the very significant increase of volunteer winter oilseed rape infestation of spring barley stands in maize production region and Cirsium arvense (L.) Scop., Galium aparine L. . Anthemis spp., Amaranthus spp., Chenopodium spp., Atriples spp., Lamium spp. and Tripleurospermum perforatum (Mérat) M. Lainz infestation in sugar beet production region and Lamium spp. in potato production region. S ignificant increase was detected by Avena fatua L. infestation in sugar beet production region. Very significant decrease of Chenopodium spp and Galium aparine L. infestation was detected in maize production region and significant decrease was detected by Anthemis spp. infestion. After herbicides control the significant changes in weed flora were noted in term of abundance and share of some weed species on total weed community The originality of result is in mapping the weed species in cultural crops .

weed infestation, spring barley, mapping, temporal dynamic

Presentation: oral