Minimizing environmental impacts of grassland weed management: can Cirsium arvense be controlled without herbicides?

Published source details Pywell R.F., Hayes M.J. & Tallowin J.B. (2010) Minimizing environmental impacts of grassland weed management: can Cirsium arvense be controlled without herbicides?. Grass and Forage Science, 65, 159-174.
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This study is summarised as evidence for the following.

	Action	Category
	Control weeds without damaging other plants in conservation areas Action Link

Control weeds without damaging other plants in conservation areas

A replicated, randomized, controlled study in 2000-2005 on the effectiveness of control strategies on creeping thistle Cirsium arvense numbers at two pastoral farms in England and Wales (Pywell et al. 2010) found that lenient grazing was most effective for long-term control. In a lowland cattle and sheep system and an upland sheep system, thistle numbers decreased under lenient grazing (cattle grazed to 8-10 cm, sheep 6-8 cm) whereas they remained constant or increased under heavy grazing regimes (cattle grazed to 5-7 cm, sheep 3-5 cm). Herbicide wiping gave the most rapid and effective control and cutting was one of the least effective measures, however, the effects of all weed control sub-treatments were short-lived at both sites. Six grazing treatments (a combination of lenient and heavy grazing) were applied to plots in a randomized block design with three replicates. Five weed control sub-treatments (thistle cutting, herbicide wiping, cutting and wiping, controls) were undertaken within grazing treatments using a split-plot design with replication at the block level; hay cutting on a three year rotation was also undertaken at one site. Data on thistle shoot density and effects on non-target broadleaved plants (rooted frequency) were obtained within each sub-treatment plot (2000-2005). This study is also described in a 2004 Defra report (Pywell et al. 2004).

Additional references:
Pywell R., Tallowin J. & Masters G. (2004) Effects of grazing management on creeping thistle and other injurious weeds and integration of grazing with weed control. Defra report BD1437.