Grassland weeds, particularly when they reach density levels of 10-20 % in swards, will have a significant effect on sward production.
Heavy infestations of chickweed have been found to reduce silage yields by up to 65% and there is also a direct correlation between dock and spear thistle ground cover and grass yield – every 1% increase in ground cover results in a 1% decrease in grass growth.
To effectively control grassland weeds it is important to understand which species are present and their individual growth habit.
When establishing new leys annual weeds are the most common problem and a wide range of species can appear. However, most fade away once the sward has been cut and the density of the sward starts to increase. Common chickweed is an exception to this rule and can appear in established grasslands where there are bare patches of soil.
Biennial weeds

Biennial weeds, such as ragwort and spear thistle, could have a significant impact on grass productivity particularly in rotational leys. The plants germinate and produce vegetative growth in the first season and then flower and die in the second.

Perennial weeds
Many perennial weeds exist in grassland and can have long term implications for sward productivity. Perennials, such as creeping thistle, buttercups and docks, can appear in a variety of ways in the sward. They may survive as rhizomes or roots in the soil during reseeding and consequently appear in the new ley. Disturbing the seed bank at reseeding can also encourage new weeds to generate.

Docks are one of the most detrimental weeds in the grassland sector and consequently the Weeds Act 1959, requires that landowners control areas of significant dock infestation. They produce a large number of wind transmitted seeds which can generate at any stage throughout the growing season. A large tap root and rapid growth response to nutrient inputs, an ability to grow in low light conditions and a resilience to trampling from animals, all fuels its competitiveness in grassland swards.
The seed is incredibly resilient (lasting over 25 years) and can be passed through the gut, stored in slurry and reapplied to land where it can germinate. As a result, docks can rarely be removed by one application.

Controlling weeds as they increase in size becomes more difficult, so by controlling them at the correct growth stage is advisable. This can be done easily on the grazing rotation through spot spraying as soon as the cows have finished grazing each individual paddock. In doing so, weeds are easier to see, and are likely to be actively growing (encouraging uptake of the herbicide), maximising the uptake of herbicide efficiently.
Please ring Sally on 07590 767655 to discuss a competitive price on all your grassland sprays.
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