Mechanical and thermal weed control and use of bio-preparations in winter oilseed rape

Abstract

Researches were conducted at the Experimental Station of Aleksandras Stulginskis University. This study aims to identify and assess the impact of thermal and mechanical weed control methods on winter oilseed rape (WOR) crops and weed competitiveness during the autumn vegetation period in an organic farming system, with and without the use of bio-preparations. Experimental treatments were: non-chemical weed control methods (Factor A): 1 – thermal (water steam), 2 –mechanical (inter-row loosening); and bio-preparations (Factor B): 1 – no application and 2 – with application. During experiment in the autumnal vegetation period before the use of weed control methods in the organic WOR crop, up to 21 weed species were found in 14 families, including up to 19 annuals and only up to three perennials. In 2013, meteorological conditions were more favourable for the growth and development of WOR than in 2012, therefore in 2013, the density of the WOR crop was on average 38.8% higher. Prior to the weed control application in 2013, the number of weed seedlings was, on average, 1.9 times higher than in 2012, but the dense oilseed rape crop had higher smothering capacity. In 2013, in WOR crop without the use of biopreparations, the number of germinated weed seedlings was higher (1.2–1.3 times) compared to the crop where bio-preparations were used. The use of biopreparations in the thermal weed control plots significantly (P ≤ 0.05) reduced the number of weed seedlings (20.4%). The assessment of the efficiency of weed control methods revealed, that without the use of bio-preparations, mechanical weed control efficiency was 3.6 to 4.5 times higher than the thermal weed control efficiency. Bio-preparations enhanced thermal weed control efficiency (from 4.5 to 21.8%), but mechanical weed control efficiency was reduced from 6.8 to 23.1%.