THE EFFICIENCY OF HERBICIDE APPLICATION AGAINST WALDSTEIN'S SPURGE (EUPHORBIA VIRGATA WALDST. & KIT) IN A FALLOW FIELD AND HERBICIDE EFFECT ON WHEAT YIELD IN THE ALTAI REGION'S OB RIVER AREA
Weeds reduce dramatically the yield amount and quality of all crops. According to the All-Russian Research Institute of Agricultural Economics, direct damage caused by weeds throughout Russia reaches 30% of the actual yield. In the 20th century, Waldstein's spurge (Euphorbia virgata Waldst. & Kit) is one of the most persistent weeds in the Altai Region. If there are more than 10 weed stems per square meter, the loss reaches three fourth of the yield. Waldstein's spurge (Euphorbia virgata Waldst. & Kit) is one of the species that is more resistant to widely used herbicides. The best way to control this weed is to use herbicides on a fallow field. We used herbicides from three classes of organic compounds with different rates of consumption and one mixed factory agrochemical. The weeds were counted from 2013 through 2016 on trial plots. On the following year, the fields were sown with spring wheat and we estimated the yield. The best results in Waldstein's spurge control were obtained by applying the herbicide Roundup (aqueous solution). With the consumption rates of 8.0 and 6.0 L ha, the biomass decreased by 89.3 and 88.2%, respectively. The application of Dianat (aqueous solution) reduced Waldstein's spurge herbage to 86.5% with a rate of 0.8 L ha. Gorchak (water-glycol solution) with a rate of 2 L ha reduced the weed herbage to 86.2%. The highest yield on the following year after chemical fallowing (4-year average) was obtained on the plots treated with Roundup (aqueous solution) - 0.211; 0.218; 0.228 t ha in accordance with the consumption rates.