Expert advice

Couch grass – effective control

Crops were from the very beginning accompanied by unwanted plants – or weed. Their pressure and their species largely depend on crop rotation, the type of soil and the utilised herbicidal treatments. In all crops, one can differentiate between weeds that are easy to control and difficult to eliminate, the control of which often requires a specific strategy of action. One of the weeds that is very difficult to control during the growth of the crop is couch grass (or the common couch).

Couch grass (Elymus repens) is a weed from the Poaceae grass family, with a single plant able to produce up to 300 caryopses, a low number compared to the fertility of other weeds. In case of couch, reproduction by the vegetative organs – stolons – is much more expansive. In course of practically all kinds of treatments of the crop on a field, where couch grows, they are subjected to cutting and are spread across the entire field – one should sadly assume the rule that one fragment means one new plant. One can visualise the magnitude of spread of couch during very popular planting after the harvest using a disc harrow.

Control of couch grass in cereals is greatly hindered because they belong to the same family – grasses. In the control of couch infestation in cereals, the active ingredient of sulfosulfuron may come in handy. Should one choose to use it, one must remember two things. The first is that it cannot be used for summer and winter barley, and the second is that it limits the growth and development of couch through the destruction of leaves – however, it does not eliminate the underground parts entirely.

Complete elimination of couch grass in maize is just as difficult as in cereals, because the registered products (e. g. Nikosar 69 OD) only destroy the overground parts of this very troubling weed.

It is slightly easier to eliminate couch grass among dicots such as winter rape or sugar beet. In order to eliminate it, apply  Labrador Extra 50 EC at 2.0 l/ hectare; the active ingredient in the product guarantees the control of both the overground as well as the underground parts of the stolons.

The solutions described above are aimed at limiting the growth and development of couch grass, guaranteeing full safety of the crop. One needs to remember, however, that for this purpose one must use the highest of the recommended doses.

A different method of controlling couch grass is to use Agrosar 360 SL, a non-selective herbicide. The active ingredient within it, glyphosate, is taken up by the leaves of couch grass and transported to the stolons, which also die out. Elimination of couch grass with the use of Agrosar 360 SL is the most effective method, and best implemented after the crop is harvested, when the couch plants have 3-4 leaves (usually ca. 10-15 cm in height). Such a surface of the leaf permits very good uptake of the active ingredient from Agrosar 360 SL, translating into the complete elimination of the couch grass.