Controlling Rushes and Protecting Drinking Water go Hand in Hand

By Tim Hyde, Environment Specialist

With grass growth improving, the Rush is also thriving. The global warming/wetting weather of recent years and the resultant poaching has left many swards open to invasion by Rushes.  

How come Rushes are so hard to control? 
Soft Rush, the most common type of Rush, is characterised by an erect mode of growth with no leaves and a very tough outer skin, making it difficult to control with herbicides. Also, the plant is deep rooted with large root reserves of food. They can produce 8,500 seeds per fertile shoot/year.

What's the best way of limiting Rushes in grassland? 
Seeds from Rushes only germinate if conditions are favourable. Maintaining a fertile, dense, leafy grass sward is the best method to prevent Rushes establishing and spreading. Encouraging grass growth will, in turn, reduce the existence of Rushes. Having a fertile soil with adequate levels of Nitrogen, Phosphorous and Potassium along with a suitable pH for grass growth is critical. Avoid any poaching, overgrazing or damage to grass swards.  

What other Grassland Management Practices will limit Rushes infestation? 
Frequent topping, timely fertilisation, application of lime along with good drainage will all help limit Rushes spread. If Rush infestation is heavy, then mulching rather than cutting should be carried out before chemical control. 

What's the best method of Chemical Control? 
Whether you are licking or spraying, topping/mowing/mulching, 3-5 weeks in advance of spraying is advised to promote fresh green re-growth capable of taking in the herbicide. This also helps weaken the food reserves within the plant. Remove any mown Rushes before spraying. Soft Rush can be controlled with MCPA or 2, 4-D applied in June or July when growth conditions are good. A wetting agent can improve the spray sticking to the slender rush 'target'. These sprays will stunt grass growth and damage/kill White Clover. 

I'm in the GLAS Scheme, with some fields/parcels as Low Input Permanent Pasture – there are a lot of rushes, what's the best control method? 
Spraying of Rushes is not permitted on land parcels/fields associated GLAS Low Input Permanent Pasture (LIPP) or the Traditional Hay Meadow (THM) option in GLAS. Spot treatment is permitted in these GLAS areas. Boom spraying with herbicides will damage the grassland plant species present in the LIPP or THM sward. This could result in a penalty under Cross Compliance and GLAS. Spraying is not permitted in any SAC areas. Rushes can be controlled by topping after the 15^th July. Consult your GLAS Planner if considering any control of Rushes in land parcels involved in the GLAS scheme. 

There has been a lot of publicity about MCPA being detected in drinking water supplies and the threat to take it off the market, why is this? 
In the past few years high levels of MCPA have been found in some drinking water sources (drinking water sources can be groundwater or surface water). MCPA is very soluble so it can travel easily in waterlogged areas or water bodies. Rushes thrive in poorly drained areas (with a water table near the surface) which are prone to runoff to nearby water bodies. Herbicides can enter water bodies from leaks from storage areas; spills or drips from handling operations such as mixing, filling and washing (mainly in the farmyard); or during application such as spray drift, runoff and drainage MCPA levels are based on EU monitoring levels. Water will always find water.  MCPA residues can become attached to soil particles and in anaerobic conditions (Waterlogged soils or sediment in watercourses) can delay the MCPA appearing/being detected in drinking water. 

What are buffer zones and how do they apply to MCPA? 
When spraying Rushes with a boom sprayer you cannot spray within 5m of any water bodies or dry drains. MCPA cannot be used in weedlickers. Weedlickers can only use Glyphosate for controlling rushes. 

Are there general precautions for using herbicides to control Rushes? 
Read the product label carefully and follow recommended rates. Spray in the cool of evening or early morning to avoid scorching of grass. Avoid grazing sprayed areas for 10 days post spraying. Triple rinse the empty container and put the washings into the sprayer and spray this onto grassland. 

Summary 

• Beware! Spraying rushes can very easily lead to breaches of the drinking water standard for pesticides, particularly if using MCPA.
• All MCPA products for rush control have a 5m buffer zone from watercourses (this includes any dry drains that could hold water)
• MCPA products cannot be used in weed lickers or knapsack sprayers
• All MCPA containers should be triple rinsed after use with the rinse put into the sprayer.
• All foil lids from MCPA containers should be put back into the triple rinsed containers.
• Mechanical control should be the first option and then spray the regrowth and target only the rush affected areas.
• Do not fill sprayers from watercourses.
• Ensure that the sprayer operator is aware of any drinking water abstraction points or wells in the local area (5m to 200m Safe Guard Zones)
• Don't apply if the soil is water logged or if there is rain forecast.
• Only apply if the grass and rushes are dry and avoid windy days where spray drift could spread into watercourses