The effect of tillage system and herbicide application on weed infestation of crops of winter spelt wheat (Triticum aestivum ssp. spelta L.) cultivars

Based on a 3-year field experiment conducted on medium heavy mixed rendzina soil, the present study evaluated the effect of chemical plant protection on the species composition, number and air-dry weight of weeds infesting crops of winter spelt wheat cultivars (‘Frankenkorn’, ‘Badengold’, ‘Schwaben- speltz’, and ‘Oberkulmer Rotkorn’) sown under ploughing and ploughless tillage systems. Ploughing tillage involved skim- ming done after harvest of the previous crop and pre-sowing ploughing, while in the ploughless tillage system ploughing was replaced with cultivating. Chemical weed control included the application of the herbicides Mustang 306 SE and Attribut 70 WG. Plots where the herbicides were not used were the control treatment. On average, from 21 to 30 weed species colonised the winter spelt wheat crops compared. Galium aparine and Apera spica-venti occurred in greatest numbers and their percentage in the total number of weeds was estimated at 26–35% and 17–25%, respectively. The cultivar ‘Frankenkorn’ was the least weed-infested. Both the number of weeds in the crop of this cultivar and their above-ground dry weight were lower compared to the other cultivars. The use of reduced tillage significantly increased the air-dry weight of weeds compared to ploughing tillage. Nevertheless, it should be indicated under ploughless tillage conditions the application of chemical crop protection reduced weed biomass by 59% compared to the control treatments without crop protection