Weed control in canopy of sugar beet.

A three year field study (2005-2007) was conducted in south-western Slovakia to investigate the effect of herbicides control on weed density, diversity and herbicide efficiency in sugar beet fields. An actual weed infestation was evaluated before herbicides application and 3-4 week after application of herbicides with concordance to International scales of EWRS. Screening of each field was made on the quadrant of 1 m area with four replications. Weed infestations in general was high, 105 pieces weeds per square meter. Weed diversity varied from 19 to 23 species each year of evaluation. On the base of three years field assessment we can conclude: The evaluated herbicides control is very effective strategy for weed control in sugar beet. 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. After herbicide control Polygonum spp., Chenopodium spp. and Echinochloa crus-galli remained the dominant weed species in canopy of sugar beet. In late summer and autumn Amaranthus retroflexus, Cirsium arvense and Atriplex spp. also rise as a problem weeds. Rezumat: V trojrocných poľných pokusoch (20052007) v regione juhozapadneho Slovenska sme sledovali vplyv aplikacie herbicidov na pocetnosť, druhove zloženie a ucinnosť herbicidov v porastoch repy cukrovej. Aktualna zaburinenosť bola hodnotena pred aplikaciou a 3-4 týždne po aplikacii herbicidov podĺa medzinarodnej skaly EWRS. Hodnotenie bolo robene na snimke 1 m v styroch opakovaniach. Celkova zaburinenosť bola vysoka, 105 ks burin na m Diverzita burin bola v rozpati od 19 do 23 druhov. Na zaklade trojrocných výsledkov sme urobili nasledovne zavery: hodnotena skladba herbicidov zabezpecila efektivnu regulaciu zaburinenosti repy cukrovej. Po aplikacii herbicidov boli zistene preukazne zmeny burinoveho spolocenstva v pocetnosti burin a v zmene podielov burin na celkovom zloženi spolocenstva. Polygonum spp., Chenopodium spp. and Echinochloa crus-galli zostali dominantnými burinovými druhmi aj po aplikacii herbicidov v poraste repy cukrovej. V neskorsom lete a na jeseň sa prejavili ako problemove buriny Amaranthus retroflexus, Cirsium arvense a Atriplex spp.