Three mowings per season provide a better thistle control than two mowings.
The biggest part of such emerged thistles was covered by the already fast developed clover plants.
This initial thistle density was the basis for the efficacy determination of all control measures.
Other studies have demonstrated the importance of a dense competitive crop stand for successful thistle suppression12,13.
Repeated mowing of forage such as alfalfa or legume-grass mixtures can severely reduce thistle density.
The need for the latter is also emphasized by the frequent choice of thistle seed cake and malt culms as potential feedstuffs.
One can assume, that particularly under water stress, repeatedly disturbed and seriously weakened thistles were no longer able to emerge in our experiment.
Only a few thistles in several patches grew undisturbed.
