Mechanical control of Cirsium arvense in organic farming

Summary

Infestation with Cirsium arvense in organic cropping is an increasing problem in many parts of Europe. A very expansive root system and the ability to form new aerial shoots from root buds facilitate formation of dense patches only a few years after establishment. In the present study, repeated mowing during the first part of the growing season used in combination with a competitive crop is suggested as a control strategy, aiming at diminishing the regenerative capacity of C. arvense. In general, the results from our two experiments showed a linear relationship between the number of mowing passes and the aboveground biomass of C. arvense in the subsequent year. A comparison of the two regression lines within each experiment showed that in both experiments there was no difference between the regression coefficients, whereas the intercepts differed significantly from each other, suggesting that the presence of a competitive crop, here a grass/white clover mixture, is likely to suppress the growth of C. arvense significantly. Hence, our results support the hypothesis that a continuous depletion of carbohydrates from the root system, caused by mowing and/or the use of a competitive crop, will diminish the regrowth capacity of the plant.