Variation in weed infestation of sugar beet (Beta vulgaris L. subsp. vulgaris) depending on the intensity of chemical protection of plantations

Abstract

A floristic study was conducted over the period 2010–2012, using the Braun-Blanquet method, under which vegetation relevés were made in sugar beet (Beta vulgaris L. subsp. vulgaris) plantations in Lower Silesia. Fields with similar habitat conditions, which differed in the intensity of herbicide application to control weed infestation, were selected for observation. A total of 144 relevés were made and based on them a list was prepared of species found in fields in which different levels of chemical protection were used. A cover index and a constancy class were determined for each species found in the phytocoenoses studied. On the basis of these observations, the study found floristic variation in the investigated agrophytocenoses as af- fected by the level of intensity of weed control chemicals used. In herbicide-untreated plots, a total of 25 weed species were found and their aggregate cover index was 8705. Chenopodium album L., Polygonum persicaria L. and Setaria pumila (POIR.) ROEM. & SCHULT by far dominated among them. Herbicide use caused an impoverishment in the floristic list. 20 taxa were observed in the plots treated with the lowest herbicide rates, while with increasing rates the number of species dropped to 18. The sum of the cover indices also decreased with increasing rates, successively reaching the values of 5907, 5212 and 4356.

Keywords

• Beta vulgaris L. subsp. vulgaris
• weeds
• herbicides
• cover index
• constancy
• rates