Control Soft Rush
Rushes occur mainly but not solely on poorly drained soils of low pH. Infestations often arise in disturbed areas of pasture or where the sward is weak. Soft rush, the main weedy species, is widespread and forms tussocks that extend by means of the short creeping rhizomes from which new shoots and ultimately new plants arise. Undisturbed plants grow into clumps over 1 m tall but mowing or heavy trampling alters this to a uniform spread of shoots. It is native mostly on acid soils. Soft rush is abundant throughout the British Isles and is ubiquitous in moist situations and regions of high humidity. It prefers an open situation but can grow in partial shade.
Soft rush flowers from June to July in the south and July to August in the north, the seeds are not ready to germinate until the April after shedding. Light and moisture are required for germination. Initially, seedlings are susceptible to drying-out, shading and mechanical damage but once established they become more resistant. The rhizomes that develop form a dense horizontal mat 6 to 50 mm below the soil surface. Stout roots penetrate vertically downwards to 25 cm. Shoots commence vigorous growth in March.
Soft rush is not easy to kill selectively. The two ingredients that show some effect are MCPA and 2-4 D. Both are contained in "Headland Polo" listed under the selective weedkiller section on the Progreen website. If the weeds are large, it is best to top them to get some new young growth.
If you can spray non-selectively, any of the total weedkillers containing glyphosate would give excellent control, however, surrounding grass would also be killed. You could apply very selectively using a weed-wiper or by having a shield attached to the knapsack lance.