Effect of weeds and some methods for their control in seed production stands of sainfoin (Onobrychis viciifolia Scop.)

Abstract

During the 2007-2009 period in the experimental field of the Institute of Forage Crops a study was conducted with the purpose of investigating the effect of weeds and some methods for their control in seed production stands of sainfoin (Onobrychis viciifolia Scop.). The trial was carried out on a slightly leached chernozem on an area with a natural background of weed infestation. As a result of the study it was found: Establishment of very uniform and productive seed production stands of sainfoin required effective weed control concentrated mainly in the first year when the degree of weed infestation was the highest and reached to a number of 245 plants/m2 and the fresh weed biomass to 1311 g/m2. The chemical control method showed the highest efficacy had the highest efficiency when, in the year of stand establishment at the stage of second-fourth true leaf of sainfoin, the treatment was conducted with imazamox 40g/l (Pulsar 40) at the dose of 48 g a.i./ha or with the system of Bentazon 600 g/l (Basagran 600 SL) - 900 g a.i./ha - fluazifop-P-butyl g/l (Fusilad Forte) - 120 g a.i./ha. In the years of seed production in spring at the beginning of vegetation, the treatment was conducted with imazamox 40 g/l (Pulsar 40) at the dose of 20 g a.i./ha + adjuvant DESH at the dose of 1000 ml/ha. An alternative to the chemical method is to sow sainfoin under cover of spring barley achieving more complete use of the area in the first year, a weed suppressive and ecological effect, but some negative residual effect on the crop was also observed; The pure stands of sainfoin with chemical control of weeds had the highest seed productivity, exceeding the zero check by 24 to 28%, followed by the stands with spring barley as a cover crop with an increase of 12% and the mixed stands of sainfoin with crested wheatgrass had the lowest productivity.