Couch Grass Killer


The CMN couch grass killer is available in various versions and working widths. On all couch grass killers, the rotor is secured with an automatic clutch that switches off when the machine is overloaded. The rotor runs automatically in freewheel mode, until the revolutions on the tractor are slightly reduced, before it is reactivated. It is also common to all machines that they have a safety bolt on each individual rotor tine, which intercepts the shock from strong resistance in the field, such as large stones. Another bonus – if a rotor tine breaks, you will get a new one for free.

The CMN couch grass killer is available in working widths of 2,3,4 and 6 m, and also with or without stubble harrow. Machines with stubble harrows are either available with three-point suspension or with a as towed model. The towed model has the advantage that there is more space between the individual harrow tines, thus enabling a better passage. It is also possible to get only the rotor. This requires that the soil is loosened before using the rotor. For a more detailed description of the machine, ask for our brochure.

The CMN couch grass killer first cuts through the field with the strong tines of the stubble harrow, which are equipped with specially designed 48 cm wide wing shares and narrow tips. These shares and tips ensure that the ground is loosened and level, so that the rotor can bring the root weed to the surface. The rotor rummages through the soil while rotating slowly against the direction of travel, and the organic material, e.g. the roots of couch grass, thistle, mugwort, etc. are captured and exposed.

The working depth is 8-14 cm, depending on the nature of the soil. The lighter the soil, the deeper it should be worked, since the roots are deeper in sandy soil than in clay. Tillage releases nitrogen and gives weed roots that remain more space. It is therefore very important that the entire root network is brought up to half a plow depth in order to prevent the remaining root weed from growing.

The couch grass problem

Couch grass is a greedy plant that competes with crops for light, water and nutrients and it is capable of reducing the crop yield by 30-50%. The table below shows the reduction of spring barley yield due to couch grass. Source: Landscentret planteavl, Denmark.

Amount of couch grass per m2 in June  Loss of yield








The combination of the slowly moving rotor and the high density of the soil ensures that soil and stones pass underneath the rotor, whereas the organic material is pulled over the rotor and is placed on top of the soil for drying or collecting.

Fighting weeds, impact and timing. A good rule of thumb is that you treat the field with the couch grass killer immediately after harvest to cut the weed roots completely and bring them to the surface. This first treatment will reduce the root of weeds by about 80%. If a by crop is sown at the same time, it will germinate together with waste seeds and weed seeds. At the same time any straw residues are composted faster, the washing out of nitrogen is minimized, the oxygen content in the soil increases and thus the working hours pr. ha are reduced.

The next treatment of the field with the couch grass killer should be done immediately before plowing, firstly to incorporate aftercrops, and secondly to expose 80% of the root weeds that survived the winter. The couch grass roots are now placed on top of the soil. They can now be placed in the bottom of the forrow, with correct adjusted frontploughs, and will not come op again. Conclusion: Sorting is very important when fighting root weeds.

CMN couch grass killer with seed sower

If you would like additional safeguards against weeds it is possible to have your couch grass killer fitted with sowing equipment so that the same machine can be used for controlling root weeds and establishing new crops.

Regardless of whether or not you would like to plow the soil, the advantages are as follows:

Next year’s root weed problems are located 5 – 7 cm down in the upper soil. When using the combined CMN couch grass killer with sowing machine, couch grass that has not been plowed under will be exposed and dry out.

With CMN couch grass killer you can achieve effective root weed control and, subsequently, you are not dependent on long periods of dry weather.