The project is seeking to develop new strategies for pesticide-free mechanical management of weeds, with the focus on timing and frequency in order to reduce herbicide use.
Preliminary examination of data from 2008 and 2009 indicates that different mechanical treatments can have a small negative effect on the occurrence of the three test weed species; clover, daisy and dandelion. Harrowing and verticutting seem to have a small positive effect on the grass cover. However, the changes in occurrence (negative and positive) are only a few percentage units. So far there are no indications that the methods being tested have the ability to effectively reduce weed occurrence (although a number of data still need to be analysed).
Data from the two field experiments (original project) are in the process of being analysed and a final report will be produced in spring/summer 2013. The analysis is focusing on the effect of the different management practices. The occurrence of weed species during the grass growing season is also being analysed. The weed composition has been examined in spring, early summer, late summer/early autumn and late autumn. Analysis of these data will produce valuable information regarding the behaviour of weed species under an intensive mowing regime.
Data from the weed burning experiment are also in the process of being analysed. The results will be included in the final report. The hypothesis is that a burning intensity can be found at which some weeds species are damaged, but the grass survives. Unfortunately the planned collection of experience from scalping and the use of composted tea did not occur. Data from greenkeepers were not sufficient.
Many greenkeepers are searching for methods to reduce earthworm casts because they are seen as perfect niches for germination of weed seeds. At Furesø golf course, Thomas Pihl (head greenkeeper) performed a number of experiments on reducing earthworm casts. Experiences from these experiments will be summarised in a short paper.
Forest & Landscape, University of Copenhagen-LIFE, Rolighedsvej 23, 1958 DK-Frederiksberg C. Denmark