Weed control in Sunflower (Heliantus Annus L.) on the interface of agro-climatic conditions of maize and sugar beet growing region

DOI: 10.15414/afz.2014.17.04.115–121Received 30. June 2014 ǀ Accepted 1. October 2014 ǀ Available online 24. November 2014In the experiment, we focused on the occurrence of weed density and weed diversity, in  maize and sugar beet growing region and the effectiveness of herbicide treatments on field experiment performed on site Santovka and Plavé Vozokany in canopy of sunflower (Helianthus annuus L.) in 1998 – 2000. Plavé Vozokany site is located in the southeastern part of the district Levice in maize growing production region. The average daily air temperature in the region is a 9.6 °C, and the annual amount of rainfall represents 604 mm and 330 mm during the growing season respectivelly. Santovka, the second experimental site, is located in the northeastern part of the district of Levice in sugar beet growing region. The average daily air temperature in the region is 9.2 °C and the annual amount of rainfall represents 637 mm and the annual amount of rainfall during the growing season is a 354 mm. Actual weed infestation was carried out by the numerous method with a five replication on the control treatments (without herbicide application), as well as on the areas treated with herbicides.  The occurence of weeds in sunflower was assessed for 3 times per growing season. The evaluated sites were infested on the level of high weed infestation. The total abundance of weeds without herbicidal treatments ranged from 39.62 pcs to 63.50 per m-2. Herbicides application effectively decreased the weed infestation in range from 3.13 pcs to 14.81 pcs  per m-2. The most dominant weed species in the canopy of sunflower was group of one year late spring weeds as fallows:  Chenopodium album L., Echinochloa crus - galli (L.) P. BEAUV, Persicaria lapathifolia RAF. S. F. GRAY, Persicaria maculata RAF. S. F. GRAY, Amaranthus retroflexus L. and Atriplex sp.. Another most abundant weeds species designated as very dangerous species were Tripleurospermum perforatum (L.) SCHULTZ-BIP., Avena fatua L., Elytrigia repens (L.) DESV, Cirsium arvense (L.) SCOP. and  Convolvulus arvensis L.. In pursuing the weed species diversity in Plave Vozokany site, we found medium dependence on air temperature during the year (r= 0.363427), and indirect dependence with rainfall pattern (r= -0.08196). The average weed density was in the indirect dependence on the air temperature (r= -0.98317), but strongly dependent on rainfall (r= 0.889926). Higher weed infestation was noted in the growing years when early spring to early summer was warm and humid. Lower weed infestation was noted when this period was dry. Differences in overall weed infestation, as well as the effectiveness of the used herbicides between experimental sites were at the same level of importance.Keywords: sunflower, herbicides control, weed density, weed diversit

Temporal dynamics of actual weed infestation in the sugar beet canopies

The aim of this study was to detect the most harmful weeds in the canopies of sugar beet during the years 1999-2009 in the Slovak Republic. The actual weed infestation was evaluated 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. Temporal dynamics of all weed species in the canopies of sugar beet were statistically analyzed. In the sugar beet fields the most problematic weeds were: perennial weed (Cirsium arvense(L.) SCOP, Elytrigia repots (L.) DESV, Convolvulus arvensis (L.)), annual weeds (Chenopodium spp. Amaranthus spp., Atriplex spp., Persi-caria spp., Echinochloa crus galli (L.) BEAUV., Datura stramonium (L.), Mercurialis annua (L.), Panicum capillare (L.), lea xanthiifolia Nun.) and cultural crops winter oilseed rape (Brassica napus (L.)). Temporal dynamics of actual weed infestation depend on climate conditions of production region, forecrop and canopy health condition. The most dangerous weed species were Persicaria spp., Amaranthus spp., Atriplex spp., Chenopodium spp. and Echinochloa crus galli (L.)P.BEAUV, which infested more than 90 % of sugar beet fields in maize and sugar beet production region