Weeds on roadways and open spaces – first results from the CleanRegion Project.
Dr. Arnd Verschwele – Institute for Weed Research.
Weeds may impair road safety on roadways and open spaces and are considered undesirable by many for aesthetic reasons, and may result in high maintenance costs being incurred if left uncontrolled. As strict regulation of chemical control measures is approved in exceptional cases only and is rejected in principle in a number of towns and cities, this raises the question as to the effective alternatives that may be used.
Developing and implementing solutions is the aim of a three-year-long EU project involving 20 partners from 7 different countries.
Weed infestation in 36 largely untreated areas of the city of Brunswick [Braunschweig] and other partner cities was evaluated according to standard experimental protocol. Altogether more than 40 species of plants were found on pavements in 2005, of which Taraxacum officinale, Poa species and type, Plantago major and Polygonum aviculare occurred most frequently over the whole vegetation growth period. 26 species of weed occurred only sporadically with a frequency of less than 1%. The number of plant species decreased from 36 to 20 in the course of the vegetation growth period.
5 methods of control were each tested at 3 locations in 2005 and 2006: a) burn-off, b) weed brush, c) steam, d) hot foam, and e) Rotofix (roller wiper equipment for applying herbicide). These devices were used up to 3 times during the vegetation growth period.
With the exception of the poor effectiveness of the burn-off, the other methods, in some cases, significantly impeded weed infestation. The degree of efficiency of the hot foam method and the Waipuna system, in particular, were comparable to treatment with herbicide.
The degree of success of the control depends largely on the particular conditions of the location. Regardless of the authorisation required to use herbicides with the Rotofix device, the roller wiper process is unsuitable for, for example, controlling moss and small weeds. The weed brush is unsuitable for treating uneven surfaces with a large number of joins but has advantages when it comes to extensive, initial weed infestation. The hot-water method, using steam or foam, provides adequate heat action in addition to killing the weed seeds. In the final analysis, all the methods tested make heavy demands on the technology of these devices and their operation.
One main focal point for further studies will involve combining control methods that have an even greater dependency on the conditions on the ground. Once the results from all the project partners have been collected and analysed, action guidelines based on these can be created for communal amenities. For further information, go to www.cleanregion.dk.