Weeds on pavements and their control

Extensive vegetation surveys on pavements have been conducted in the city of Braunschweig from 2005 to 2007 as part of the EU project CleanRegion. The survey was conducted at 165 plots situated in residential and industrial zones as well as in parks and recreation areas. During the complete period we found 78 weed species e.g. groups of weeds. Most frequent (> 12 %) were bryophytes, Sagina procumbens, Poa annua, Taraxacum officinale and Polygonum aviculare. 26 species, including many arable annual weed species occurred very sporadically (frequency < 1 %). The mean weed coverage was 6.3 % but was much higher in some cases in industrial zones. However, there were no significant differences of the weed coverage in the three different zones. Additional weed control trials including physical and chemical control measures have been conducted at 8 sites located in Braunschweig in 2005 and 2006. Based on the weed coverage at the end of vegetation period the following efficacy has been achieved: 1. Rotofix (71 %), 2. hot foam (59 %), 3. hot steam (35 %), 4. weed brush (35 %), 5. flaming (13 %). The investigation indicates that beside the efficacy we also have to consider the weed species and density as well as the pavement condition. Different methods should be combined in order to avoid selection pressure of certain weed species